HomeMy WebLinkAbout18-085� �', � � i �i
A RESOLUTION OF THE CITY OF DENTON ADOPTING THE "RENEWABLE
RESOURCE PLAN99 TO MEET THE FUTURE NEEDS OF ITS ELECTRIC
CUSTOMERS WITH 100% RENEWABLE ENERGY AND RESCINDING RESOLUTION
NO. R2016-014 (THE "RENEWABLE DENTON PLAN").
WHEREAS, the City Council would like to meet the future energy needs of its electric
customers with 100% renewable energy; and
WHEREAS, in 2017 the City hired Enterprise Risk Consulting ("ERC") to both review
the Renewable Denton Plan (approved by the City Council under Resolution No. R2016-014) and
develop a plan to meet the energy needs of its electric customers through 100% renewable energy;
and
WHEREAS, ERC developed the Renewable Resource Plan which would allow the City
to meet the goal of providing its electric customers with 100% renewable energy as early as either
2020 or 2024; and
WHEREAS, ERC presented the Renewable Resource Plan to the City's Public Utility
Board ("PUB") on January 22, 2018; and
WHEREAS, the PUB voted 6-0 to recommend that the City's Council approve the
Renewable Resource Plan with the goal of ineeting the future energy needs of the City's electric
customers with 100% renewable energy as early as 2020.
NOW, THEREFORE, THE COUNCIL OF THE CITY OF DENTON HEREBY
RESOLVES:
SECTION 1. The recitals set forth in the preamble of this Resolution are incorporated
into and is a part of this Resolution for all purposes.
SECTION 2. The City Council adopts this Resolution approving the Renewable Resource
Plan to achieve the goal of providing the City's electric customers with 100% renewable energy
as early as 2020 and in a manner that ensures electric reliability and competitive electric rates. The
Renewable Resource Plan is attached as Exhibit "A" and is incorporated into and is a part of this
Resolution for all purposes.
SECTION 3. The City Council rescinds Resolution R2016-014 (the "Renewable Denton
Plan")
SECTION 4. This Resolution shall take effect immediately after its adoption.
PASSED AND APPROVED on February 6, 2018. �'� �"°�
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CHRIS WA°� i��, MAYOR
ATTEST:
JENNIFER WALTERS, CITY SECRETARY
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APPROVED AS TO LEGAL FORM:
AARON LEAL, CITY ATTORNEY
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December � 2017
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Neil McAndrews
Larry Lawrence
Enterprise Risk Consulting, LLC
Table of Contents
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Section
Executive Summary
1.0 Introduction
2.0 Goals of the Resource Plan
2.1 Plan Objectives
2.2 Customer Preference & the Competitive Market
2.3 Efficient Management of a Renewable Resource Power Supply Portfolio
2.3.1 The Treatment and Management of Renewable Resources as an Energy Supply Hedge
2.3.2 Managing a Renewable Resource Supply Portfolio in the ERCOT Market
3.0 Information Gathering
4.0 Renewable Resource Plan Inputs & Analysis
4.1 Evaluation Factors
4.2 Gap Analysis
4.3 Production versus Load Profiles
4.3.1 Daily Profiles
4.3.2 Seasonal Profiles
4.3.3 Quality of Specific Renewable Resources
4.3.3.1 Producer Production Data Bias
43.3.2 Wind Location Considerations
43.3.3 Solar Location Considerations
433.4 Additional Location Considerations
4.4 Congestion (Location Basis) Considerations
4.5 Regulatory Environment
5.0 Renewable Resource Portfolio Model Development
5.1 Modeling Factors
5.2 Portfolio Modeling
5.3 Portfolio Optimization
5.4 Demand Response (Demand-side Management)
6.0 Reporting & Summary Analysis
6.1 The Denton Energy Center
6.2 The Benefits of the Denton Renewable Portfolio ("DRP")
6.3 Risks and Opportunities in Selecting Renewable Resources
6.3.1 Resolving the Renewable Status of the Whitetail Supply
63.2 Planning Risks
6.4 The Path to 100% Renewable Resources
6.5 Additional Considerations
7.0 Summary of Recommendations
Appendix A- Hedging 101 & Applications for Denton
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 2
Executive Summary
Introduction & Goals of the Resource Plan
This resource plan incorporates the addition of the Denton Energy Center ("DEC") to Denton's
power supply portfolio, and focuses on analysis and recommendations for meeting Denton's
targets for completing its power supply portfolio through the acquisition of a diversified set of
power purchase agreements from renewable energy resource providers.
The focus of this plan is on the examination of the effects and risks of various locations of
renewable resources, of how the various types of renewable resource production profiles blend
with existing portfolio supply assets to achieve as much diversification as possible (to reduce
cost and supply variability), and of a variety of pricing factors including least-cost resources and
manageable transmission congestion exposures.
This resource plan also focuses on the strategic design and tactical daily management
requirements to efficiently and economically operate a power supply portfolio comprised of
renewable resources. Because of the intermittent nature of energy production from renewable
resources, and the much wider geographic footprint of power generation resources than is
usual for an electric utility, a daily supply portfolio and risk management process involving
production forecasting, supply balancing transactions, and seasonal, monthly and daily
congestion (basis) hedging becomes paramount to the successful operation of a power supply
portfolio of renewable resources.
The main goal of the resource plan is to identify and recommend least-cost renewable
resources so that Denton can meet its resource goal of 70% to 100% renewable energy,
The goal can be broken down into five objectives: least-cost supplies, uncertainty (risk)
reduction, sustainability (environmental and production), competitiveness, and the efficient
management of a renewable resource power supply portfolio.
Successfully achieving Denton's renewable resource goals involves several critical strategic
planning and tactical operational elements:
1. Location and production profile of the renewable resource(s)
2. Managing the supply portfolio by completing an industry best practice opposition
hedge, including:
o Scheduling of the resource output,
o Avoiding double purchasing (i.e., "monetizing" the renewable resource by selling
it into the market while simultaneously purchasing energy to serve load), and
o Managing basis (congestion) risk
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC
An important goal and guiding principle for this resource plan is that the design and
management of a renewable resource supply portfolio must to take into account the structure
and conceptual design of the ERCOT market. This resource plan is based on managing Denton's
renewable resource power supply portfolio in concert with the intent and design of the ERCOT
market, through the use of industry best practice risk management techniques and ERCOT-
specific market instruments.
ERCOT is an "energy-only" market. Load in ERCOT does not need to acquire and meet a
capacity requirement to ensure that adequate resources on the grid are available so that the
demand for electricity can be met at all times. The ERCOT market design requires that load
only needs to acquire adequate energy schedules, and most of the supply risk is then
neutralized.
In the ERCOT energy-only market, firming is not an explicit requirement. ERCOT automatically
"firms" inadequate supplies to meet all load requirements—the important risk management
focus is on managing the "firming" in a least-cost manner, both in terms of energy balancing
purchases/sales and managing congestion price risk.
Evaluation Factors
The evaluation factors for this resource plan are grouped around the two of the resource plan
objectives: 1) least-cost and 2) reducing uncertainty (risk).
Regarding goal 2) reducing uncertainty (risk), the primary focus from the perspective of
evaluation factors for various renewable resources is on best-fit factors for Denton's energy
supply portfolio. These best-fit factors include the production profile match relative to
Denton's daily and seasonal load profiles, balancing the need for selling excess supply and
purchasing shortages, the quality of each resource's production, access to transmission
interconnections, and minimizing transmission issues with a particular focus on avoiding or
reducing congestion exposure.
The recommendations in this resource plan will range in quantity based on the uncertainty of
counting Whitetail as a renewable resource. This leaves Denton needing between 9% and 26%
in additional renewable resources to meet its minimum goal of 70% renewable, or between
39% and 56% to meet the target of 100% renewable.
Production versus Load Profiles
Figure ES-1 shows ERCOT data with representative production and load profiles for a typical
summer day. Represented are production profiles for "Wind", which would be West Texas
wind, plus Coastal wind, Panhandle wind, and Solar. These are plotted against a typical
summer load profile for a load-serving entity with a substantial amount of residential and
commercial customers.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 4
Figure ES-1- ERCOT Summer Renewable Production Profiles (source: 2016 State of the Market
Report for the ERCOT Electricity Markets)
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Wours of the Day
Takeaways on daily production profiles:
• West Texas wind offers the worst match against load. The production increases during
less valuable, lower priced hours for energy.
• Solar and Coastal wind offer the best (on-peak) match against load, and can displace
market purchases of more expensive on-peak energy.
• Panhandle wind is somewhat superior to West Texas wind.
� Coastal wind production is at a low point during lower priced hours (i.e., it offers the
benefit of producing less when production is less valuable).
• Coastal wind and Solar have traditionally commanded a premium in terms of market
pricing, but with overall prices for renewable resources falling, the cost premiums
versus other renewable resources have compressed, making the assets more
compelling:
o Current low prices are attractive
o Their production profiles are a better fit for Denton's load, and are a better
complement to Denton's existing renewable resources such as Santa Rita (West
Texas wind), as opposed to adding more West Texas wind to Denton's supply
portfolio, or adding Panhandle wind.
Seasonal variations in both production and load profiles will require active portfolio
management to balance Denton's supply portfolio. Daily management will involve forecasting
renewable resource production and then transacting in the ERCOT DAM to sell power during
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 5
hours with excess supply, and purchasing power during hours with a supply shortage. The
optimal balance between excess and shortage is one of Denton's decision criteria for
determining renewable resource acquisitions.
During a typical summer day, wind output is typically low, while solar output is high (but not
necessarily at its highest during a calendar year), and the DEC has a higher likelihood of being
dispatched. Assuming a portfolio with a blend of wind and solar renewable resources,
seasonally low wind output will necessitate market purchases during off-peak hours. The
combination of solar production and DEC production could cause an excess of supply during
certain on-peak hours and would necessitate market sales.
During a typical spring day, wind output is typically at its highest while solar output is modest,
and the DEC is unlikely to be dispatched. Assuming a portfolio with a blend of wind and solar
renewable resources, seasonally high wind output would necessitate market sales during off-
peak hours. The combination of only modest solar production and lack of DEC production could
cause a shortage of supply during certain on-peak hours and would necessitate market
purchases for supply/demand balancing.
An important consideration in evaluating renewable resources is to verify and correct
production output claims of renewable resource developers. Both solar and wind developers
typically include a bias to expected performance. Producers typically over-estimate the
efficiency of their installations to attract investors. To adjust for these biases, independent
data from the National Renewable Energy Laboratory ("NREL") and ERCOT was used in this
resource plan. NREL tools allow verification by specifying what type of PVi cell is involved, along
with the tilt of the PVi cells mounts, including fixed, single or dual axis mounting. These tools
can be used to produce hourly production curves for various seasons and at various locations
across the state. For wind resources, ERCOT has an extensive database of wind production
profiles across the state.
The reduction (correction) to developers' claims for wind resources are on the order of 5% to
8%. The reduction in actual performance of solar production is 15% or more depending on the
equipment type and installation design.
Location Considerations
In terms of location preferences for wind and solar locations, the following conclusions were
reached.
More consistent output and a higher capacity factor supports the choice of Coastal wind.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC
Advantaees of Coastal wind;
• Less with ERCOT System wind, producing higher output during the summer afternoons.
• Lower congestion risk with lower output during the spring and fall when high West
Texas Winds increase congestion.
• More reliable for forecasting because it depends on the land, ocean effect.
• Coastal wind resources in the ERCOT South Zone are away from resources built in West
Texas, and they are closer to potential retirements of generation in East and South
Texas.
�is�dv�nt:� �s �f ����t�l �ri�d:
� Coastal wind PPAs usually command a cost premium compared to other wind resources.
• Coastal environmental considerations (e.g. hurricanes, sensitive habitat).
• Subject to build restrictions (e.g., near U.S. Air Bases).
• A great deal of additional load being added in the area.
Despite these disadvantages, the advantages of Coastal wind, especially regarding the fit to
Denton's supply portfolio, outweigh the disadvantages.
Solar irradiance (the power per unit area received from the Sun) as a function of Iocation is a
primary evaluation factor for solar renewable resources. Solar irradiance is impacted by
latitude, potential for cloud cover, and temperature factors. An optimal location representing a
balance of sufficient irradiance, limited cloud cover, and manageable congestion would be close
to Midland, Texas.
An additional consideration for evaluating optimal resource locations is the projection of
generation additions and retirements in ERCOT. With more renewable resources expected to
be developed, and with conventional resources such as coal-fired generation expected to
experience increased retirements, congestion issues may be exacerbated.
ERCOT projects an increase in generation in the West and a decrease in generation in the East
as can be seen in Figure ES-2. Yellow to orange circles indicate generation additions, while blue
circles indicate projected retirements. This will create a decisive West to East flow of
production.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC
Figure ES-2
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In considering resource additions, Coastal wind is not facing heavy competition. Adding
resource capacity in an area with retiring conventional generation, and closer to load than the
majority of renewable resource additions, presents several advantages. Optimal site selection
is more limited for solar however, due to the need to maximize irradiance while minimizing
rainfall and cloud cover.
Lastly, another location consideration is the access to transmission. Pricing points cluster at
wind resources near big substations and 345 kv interconnects. Ideally, the better locations are
in between the pricing clusters and urban areas, east of the clusters in the western region that
are dominated by wind resources, and along the coast closer to Corpus Christi than Brownsville.
�Ct�r� �sti��r'r I�I��� iN� �����i��r��;i[�ns
Congestion hedging is an important component of completing the opposition hedge, and of
carrying out an efficient internal portfolio management operation for renewable resources, as
discussed previously. Congestion hedging is like insurance - it is important to insure exposures
in a complete manner.
ERC's extensive experience with Congestion Revenue Rights ("CRR") management and hedging
for several clients indicates that not only is the net cost of congestion hedging acceptable, but
CRRs often pay for themselves when exposure risk increases.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 8
The use of CRRs should not be avoided because of possible curtailments or derations. In fact,
the principal hedging method in the market to limit curtailment risk is the purchase of a CRR. A
CRR will make the owner indifferent to curtailment because it will fix the price between two
points.
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The potential for changes in ERCOT is another factor in the resource plan analysis. ERCOT
continually changes the way the system operates.
An example is the proposal to change the market design to incorporate marginal line losses.
This will add costs to resources that are farther from load zones. A change in the ERCOT market
design to incorporate costs associated with marginal line losses would favor Coastal and North
Texas wind resources because they would be closer to a load zone. These two wind resources
would reduce the potential risk from the adoption of marginal losses, and CRRs would still be
available to mitigate the risk to some degre.e.
Renewable Resource Portfolio Modeling
The following is a list of variables considered in qualitative and quantitative modeling:
• Natural gas prices
• Power prices
• ERCOT Hub North heat rates
• DEC heat rate and estimate of variable 0&M
• Denton load growth
• Renewable resource production profiles
� Renewable Prices
w� Basis costs (CRRs and locational basis floating price exposure)
• CRR prices, Point to Point prices
• Regulation changes (e.g., incorporation of Marginal Losses, Local Reserves, potential
federal Solar tariff)
• PTC and ITC effects on supply and prices (curtailment frequency)
• Coal and natural gas plant retirements
� Renewable saturation in certain regions
• Lubbock ERCOT integration
• Proposed new resources
An important aspect of modeling portfolio costs and developing a portfolio mix that meets the
twin resource plan goals of least-cost and uncertainty (risk) reduction is to achieve as much
diversification as possible in the supply portfolio. One important measure of diversification is
the correlation of various renewable resource production profiles. The goal is to assemble a
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 9
portfolio with a mix of less correlated resources so that the overall portfolio production is more
consistent. Combining renewable resources with lower correlations reduces risk and improves
overall supply portfolio correlation with Denton's load, and it improves forecast reliability.
An additional diversification factor is the location of resources especially in regard to
congestion exposure. Diversifying the supply portfolio reduces overall congestion risk exposure
and also contributes to more consistent economic performance.
The portfolio modeling for this resource plan was based on a blend of correlation analysis and
scenario valuation. Various mixes of renewable resource quantities, constrained by the results
of the correlation analysis, were valued according to the ranges of natural gas and power price
projections, along with related DEC dispatch scenarios, with the objectives of finding the least-
cost portfolios with the lowest cost variability.
The production profiles of various renewable resource were screened to determine how the
profiles performed against historical prices. This involved calculating the balancing costs for
each profile to determine the net effective cost of each resource type. Balancing costs are a
blend of spot market purchases of market power when renewable production fell short of load
requirements, or DEC production when the DEC was a lower priced alternative to DAM
purchases, and spot market sales of excess power when renewable production exceeded load
requirements.
Prospective renewable resources were also included, along with West Texas wind, in a portfolio
optimization model based on Modern Portfolio Theory. Quantifying the optimal resource mix is
accomplished by measuring the returns, and the variance and covariance of the individual
resources, over an appropriate period of time.
This is a widely accepted approach to portfolio design following the Modern Portfolio Theory
("MPT") developed by Harry Markowitz (who won a Nobel Prize for developing MPT). MPT is a
theory of optimal diversification; based on historical data and measures of asset returns, risk
and correlations, MPT selects the optimal diversification portfolio mix.
Portfolio optimization was used to measure the optimum percentage weighting of prospective
assets in a portfolio. The three assets considered for the portfolio were a solar asset, a coastal
wind asset, and West Texas wind. The portfolio optimization model selected additional Solar
and Coastal type wind to be added to the portfolio. It does not select other types of additional
wind into the portfolio.
Reporting & Summary Analysis
The DEC will play a role in Denton's renewable resource portfolio as a cost hedge during certain
super high-priced hours.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 10
As discussed previously, the greatest challenge in managing a power supply portfolio comprised
of renewable energy resources is balancing the supply portfolio around the intermittent
production of renewable power plants. Balancing the supply portfolio is often referred to as
"firming" inadequate supplies. As explained previously, in the ERCOT energy-only market,
firming is not an explicit requirement. ERCOT automatically "firms" inadequate supplies to meet
all load requirements — the important focus is on managing the "firming" in a least-cost
manner, both in terms of energy balancing purchases/sales and managing congestion price risk.
The results of the quantitative modeling employed for this resource plan show that the DEC
should not be the sole resource used to "firm" a renewable resource portfolio. Using the DEC
as a sole hedge is not the least cost and lowest risk option for over 75% of the hours in a year.
The low heat rate associated with most of the hours in the DAM will allow Denton to firm
intermittent renewable production with spot market purchases at a lower cost than the DEC
while avoiding congestion and price risk.
An example of when the DEC would be dispatched rather than using DAM purchases to hedge a
supply shortfall is in Figure ES-3. During a peak demand month such as August, the DEC might
be dispatched about half of the time (the periods of time without the green shading). But in
this example, even in a month like August, using the DEC as a hedge is likely not to be the least
cost and lowest risk alternative for approximately 50% of the time. Figure ES-3 also shows that
during DAM purchase hours (the hours shaded in green) the difference between the DAM fully-
hedged price and the variable RT price is negligible (average of $0.44). Participating in the RT
would be a large disadvantage to Denton because of higher risk but little-to-no benefits.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 11
Figure ES-3
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Advantages:
• The DEC is a heat rate hedge (note that it is not an energy cost hedge unless the price of
natural gas is fixed)
� It will reduce cost risk for Denton because at certain times it will be dispatched during
price spikes.
• It also provides a long-term hedge benefit in the event of accelerated retirement of
conventional fossil fuel generation resources in ERCOT that may elevate heat rates.
Disadvantages:
• As a higher heat rate generator, it offers no pricing power and offers no competitive
advantage.
• ERCOT manages the system so that heat rates don't vary much
• Its value to Denton requires that natural gas prices go up substantially in the future.
Additional Alternatives for Extr���ir� � V�I�� fir�+�n th� ���C
• Based on the last bullet point under disadvantages, Denton should be prepared to sell
DEC output forward when or if there is a spike in natural gas prices. Natural gas prices
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 12
tend to revert to the long-term mean after price spikes, so that increased value due to a
price spike may be transitory and should be taken advantage of.
The DEC can be used to sell firming services to other organizations looking to add
renewable resources. This can mean that the DEC is not used as a producing generator,
but as a contingent financial hedge (i.e., the actual dispatch and fuel use may be
unchanged but the revenue from the resource will be increased). This is because at the
time Denton might be obligated to provide firming energy, market purchases are more
likely than the DEC to be the least cost alternative.
As previously discussed, because of the mismatch in seasonal production profiles of
renewable resources versus Denton's load profile, there are likely to be periods of time
when Denton will have excess supplies (e.g., in the Spring). It may be beneficial to sell
excess renewable power during these periods using the DEC to firm the transaction.
Takeaway: The DEC will serve a role as a supply cost hedge to firm Denton's renewable
resource portfolio, but based on the financial evaluation in this resource plan, the majority of
firming the supply portfolio will be more economically efficient through purchases in the DAM.
Denton should look for opportunities to sell a portion of the DEC forward during natural gas or
heat rate spikes, and for opportunities to sell firming services or to firm sales of excess
renewable supplies.
Benefits of the Denton Rr�r��w��l� P�r�"t1��li� "��F�P")
Figure ES-4 shows the projected financial benefits of the DRP based on the range of price
projections used in the analysis for this resource plan. This is based on a portfolio where the
70% goal reached and maintained until 2023, and then additional Wind and Solar are purchased
to reach 100%. Every year enough renewables are purchased to keep up with load growth.
The chart projects the financial performance of Denton's supply portfolio based on a range of
future prices. Positive benefits would result through avoided additional costs if prices rise in
the future. Negative values would result from low price outcomes.
The main takeaway is that the Total System Benefits are completely dependent on the price of
natural gas. If gas prices rise, power prices will rise as a result, and over time Denton's fixed-
price renewable resource supply portfolio would result in avoided costs from the higher power
prices. That is the measure for benefits for both Brattle and ERC evaluations. But if gas prices
do not rise, power prices will stay around the current prices and as a result, Denton's fixed-
price renewable resources will not avoid higher market prices and fewer benefits would result.
This is the biggest uncertainty in the entire evaluation. This difference between high natural
gas prices and lower natural gas prices is a change in total benefits of approximately $575
million in 2018 dollars.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 13
Figure ES-4
ERC and Brattle Total Benefits of Denton Rewneable PortFolio ($OOQs)
($xoa,000� $o $ioo,000 $zao.aoo Ssao,000 $aoo,aao $500,000 $c�oo,000 S�oo.aoo
Considerations for Selecti����; ��rr�v�r�bl� R���a������
The analysis and evaluation for this resource plan assumes that Gibbon's Creek will be
decommissioned by 2018.
Denton can reach its 70% renewable goal with additional renewable resources from the current
RFP submissions. The additional energy to reach the goal ranges from approximately 9%
(140,000 MWh) of its load to 27% (400,000 MWh) of its load. This range depends on whether or
not the Whitetail resource is designated as a renewable resource. The current energy supply
portfolio falls far short of a balanced and diversified portfolio because solar is only 30 MWs. The
portfolio is also unbalanced because a large amount of the renewable supply is a low on-peak
West Texas wind profile (Santa Rita). Adding the Bluebell solar (30 MW) resource will still
produce very little summer on-peak production. The DEC is a heat-rate resource and therefore
does not contribute an energy hedge during peak hours (i.e., it is a heat rate hedge only until
the price of natural gas is fixed).
This leaves Denton with an on-peak energy supply gap. A minimum of 90 to 120 MWs of solar
would help balance the portfolio. To reach the 70% goal at a minimum, another 70 MWs of
Solar should be considered as an addition to the portfolio. If Whitetail is not counted, an
addition of another 120 MWs of Solar should be considered, with wind representing the
balance of energy needed to reach the 70% level.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 14
There is a series of known risks that could drive Denton to accelerate reaching the 100% goal,
or decelerate reaching the 100% goal past 2024. A particular risk in the acquisition plan is that
there is a possibility of a federal solar tariff. It is not clear how the tariff will affect prices or the
term of the additional costs, but preliminary estimates are that it could increase average costs
of solar from the current $25/MWh up to $40/MWh. Under the current price environment
$40/MWh is not competitive with wind resources.
Alternatives to avoiding the solar tariff:
• Acquire more Coastal wind resources that feature the characteristic summer peak
production profile. This is the closest substitute for solar among the renewable
resources.
Utility-scale wind resources with a storage component, now or in the future. Altering
the profile of West Texas wind into a more on-peak production profile will improve
hedge effectiveness.
Purchase solar as the tariff prices and supplies readjust to market conditions or the tariff
is no longer an issue. Denton can wait and test the market prices after reaching the 70%
level. Waiting on solar would decelerate reaching the 100% goal.
Potential purchase accelerators:
• Announced coal retirements totaling 4.2 GW of generation capacity from Vistra Energy
(Monticello, Sandow, and Big Brown) may increase power prices during the next few
months. This is likely to have much less impact on the price of wind versus the price of
solar. This could accelerate the amount of wind purchased by Denton, especially Coastal
wind as a substitute for solar.
• PTC reduction lowers the subsidy to wind producers. The supply of wind may be at its
maximum now because of the rush to beat the expiration date of the PTC. Because the
supply of available PPAs is highest now, this could be an inducement to accelerate the
acquisition of wind in a buyer's market.
• The potential for rising natural gas prices. The Iow number of drilling rigs, increasing
demand for exports, and the large substitution of the natural gas for coal in the electric
power sector could drive price increases. In the past, when steady increases in demand
for natural gas have met with a lower number of drilling rigs over a several-year period,
natural gas prices have increased dramatically (e.g., the early 2000s saw prices double
and then triple over a few-year period).
The Path to 100% Renewable Resources
The evaluation in this resource plan indicates that Denton's 100% renewable goal ("RE 100") is
achievable much earlier than 2035. There is no financial penalty or premium to moving from a
70% renewable resource goal ("RE 70") to a 100% renewable goal.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 15
Gradual Adoption Path
Denton has several paths to choose from to reach its RE 100 goal. But the first Denton
Renewable Portfolio (DRP) goal is RE 70 by the end of 2019.
The RE 70 level can be achieved by executing PPAs for low-priced supplies that have been
offered in the current Renewable RFP (Oct 4, 2017). Figure ES-5 shows a possible outcome to
achieve this 70% goal, and eventually the 100% goal by 2024. The chart includes Denton's load,
seen as a gradual increase in the light blue shaded area, additional renewable purchases
labeled "Add. Renewable" and depicted by the red vertical bars, and lines showing the
progression of the proportion of renewable resources and of the amount of supply with fixed
prices.
In the chart, the NextERA Whitetail supply is not counted as a renewable source because it is
not a physical renewable source, but uses Renewable Energy Credits (RECs) to claim renewable
status. An alternative scenario is included later in this discussion that counts the NextERA
Whitetail supply as a renewable energy supply. In either case, additional physical renewable
supplies are required. Depending on the location, price, congestion environment, and the
production profile of the resource, more supply may be added above the additional 47% of load
in energy purchases that are needed to achieve the RE 70% goal by 2019.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 16
Figure ES-5
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100% Renewable Goal 2024
20fl.6 2019 202� 2021 2022 2023 2024 d625 2026 26�7 202� 2029 2�3� 2031 2d32 2033 2�34 2035 d�36 263 7 203�
Why possibly purchase more than the 47% needed to meet the RE 70 goal? The amount of
additional supply is a function of the uncertainty of renewable production. The amount of wind
production can easily vary by 15% on an annual basis. If Denton wants to make sure that it has
at least 70% at a minimum in every year, it may need to buy additional supplies above the goal,
taking into account the annual production variability.
Another part of the acquisition path depicted in Figure ES-6 is the assumption that Denton will
purchase shorter term (1 to 4-year duration) renewable resources to adjust the RE goal to reach
100% and to constantly maintain that level. Constantly maintaining a target level can be done
with a variety of renewable resources and demand-side management programs. Besides the
new acquisitions that are needed by next year to reach the RE 70 goal, another larger supply is
the replacement of the Whitetail NextERA supply in 2024 because the contract ends in
December of 2023.
l �rbl�r �1r�a��t��r�� I��Ck�
A second path for achieving the RE 100 goal is earlier adoption. Denton would accelerate the
wind PPAs acquisition to produce the RE 100% goal four years earlier, in 2020 rather than in
2024, as shown in Figure ES-6.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 17
Figure ES-6
�
100% Renewable Goal 2020
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This accelerated wind acquisition would result in excess power supply over the next few years
due to the Whitetail non-renewable resource, and Denton would have to manage fixed-cost
risk (the risk of market prices falling because Denton would have more supply than its load for 4
years). If the Early Adoption path is selected, the excess power supply would be approximately
18% for the years 2020 through 2023. The excess supply would end with the Whitetail contract
expiration.
Including the NextERA Whitetail supply in the renewable category will also accelerate the RE
100 goal to 2020. But it also requires replacement of this energy in 2024. This is depicted in
Figure ES-7. The principal advantage of this scenario is that it doesn't produce additional fixed-
price supply (the 18% excess supply discussed previously). The principal disadvantage with
including Whitetail in the supply portfolio is that it could cause an audit risk as to the validity of
its renewable status.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 18
Figure ES-7
100� Renewable Goa� 2020
Countir�� Whitetail as Renewable
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2Qi8 2014 202D 202�. �2022 2623 2a24 �2085 2026 2627 202� 2029 2Q9Q 2031 P032 2033 2034 2035 2096 2637 2Q38
Summary of Recommendations
To reach its goal of a power supply that is 100% renewable energy, Denton should purchase
200 MWs of solar, preferably in two locations, and 100 MWs of Coastal type wind. Both of
these types resources should have low congestion risk. Most of the solar proposals are due to
come online by December 31, 2020. Several of the wind proposals will come on line in 2019.
The execution of the resource plan is dependent on actual proposals, and terms and conditions
from the RFP offers.
An optimal location representing a balance of sufficient irradiance, limited cloud cover, and
manageable congestion for would be close to Midland, Texas.
DME needs to hedge both its load with HB North to LZ North CRRs and its resources with
Resource Node to HB North CRRs for the upcoming Santa Rita Wind as well as the Blue Bell
Solar farm.
����i�iar� ��r��tirr���dw"�
In addition to the recommended amounts, types and locations of renewable resources, Denton
will need to make several decisions that will shape the development of its renewable resource
supply portfolio.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 19
+� Count Whitetail as a renewable resource?
o If not, is Denton willing to handle the additional fixed-price risk of the Whitetail
supply in addition to the fixed-price quantity of renewable resources necessary
to meet Denton's goal(s)?
• Will Denton choose to delay solar purchases because of a potential federal solar tariff?
o If so, potential alternatives include:
� Purchase additional amounts of Coastal wind as a substitute?
� Alter the profile of wind resources with storage?
w Delay solar purchases until the issue is resolved, or solar prices and
supplies adjust to the tariff
• Should Denton accelerate renewable purchases, especially of wind resources, because
of:
o increasing retirements of conventional fossil fuel generation capacity?
o scheduled reduction in the PTC?
o risk of rising natural gas prices?
• Should Denton move forward the date of the 100% renewable goal?
• Should Denton purchase additional renewable supplies above its target levels because
of the annual variance in production amounts?
� Portfolio allocation decisions—there are various allocations between Coastal wind and
Solar to meet Denton's goals (e.g., 180 MW of Solar and 150 MW of Coastal to meet a
100% goal, or 120 MW of Solar and 200 MW of Coastal). What is the preferred
allocation?
Final Version Addendum
Based on feedback from the City of Denton Public Utilities Board, and the Denton City Council,
the following decisions have been made:
• Count Whitetail as a renewable resource? No
� Will Denton choose to delay solar purchases because of a potential federal solar tariff?
No
• Should Denton accelerate renewable purchases? Yes
• Should Denton move forward the date of the 100% renewable goal? Yes
Other decisions will be finalized in the RFP evaluation process, as they will be a function of the
final economic value determined through the evaluation process and final PPA negotiations.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 20
1.0 Introduction
The City of Denton, Texas ("Denton") engaged Enterprise Risk Consulting, LLC ("ERC") to
provide strategic support by assisting with resource planning, and the design and
implementation of a revised long-term power supply portfolio and portfolio management
strategy.
This resource plan incorporates the addition of the Denton Energy Center ("DEC") to Denton's
power supply portfolio, and focuses on analysis and recommendations for meeting Denton's
targets for completing its power supply portfolio through the acquisition of a diversified set of
power purchase agreements from renewable energy resource providers.
This document is similar to a typical resource plan, except that the goal of the plan — Denton's
goal of developing a 70% to 100% renewable resource supply portfolio -- has already been
established. Instead of a typical resource plan's focus on evaluating resource and fuel types,
and various types of contracts, the focus of this plan is on the examination of the effects and
risks of various locations of renewable resources, of how the various types of renewable
resource production profiles blend with existing portfolio supply assets to achieve as much
diversification as possible (to reduce cost and supply variability), and of a variety of pricing
factors including least-cost resources and manageable transmission congestion exposures.
Another important factor that makes this plan unique is the focus on the short time window to
make decisions. ERCOT is an evolving market, and the rapid development and integration of
renewable resources creates a new world of power supply and transmission challenges. The
development of renewable resources, and their rapidly falling costs, have been driven to a large
extent by the federal producer tax credit ("PTC") and the investor tax credit ("ITC"). These tax
advantages are being phased out, and this shortens the time window for securing resources at
current prices. And recent developments with the accelerating retirement of coal and natural
gas-fired generation adds another element that may affect the current low prices on
renewables. For other types of beneficial renewable resources, such as demand-side
management (Demand Response) programs and assets, a much longer timeframe can be used
for planning and decision-making.
This resource plan also focuses on the strategic design and tactical daily management
requirements to efficiently and economically operate a power supply portfolio comprised of
renewable resources. Because of the intermittent nature of energy production from renewable
resources, and the much wider geographic footprint of power generation resources than is
usual for an electric utility, a daily supply portfolio and risk management process involving
production forecasting, supply balancing transactions, and seasonal, monthly and daily
congestion (basis) hedging becomes paramount to the successful operation of a power supply
portfolio of renewable resources.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 21
2.0 Goals of the Resource Plan
The main goal of the resource plan is to identify and recommend least-cost renewable
resources so that Denton can meet its resource goal of 70% to 100% renewable energy.
The goal can be broken down into five objectives: least-cost supplies, uncertainty (risk)
reduction, sustainability, competitiveness, and the efficient management of a renewable
resource power supply portfolio.
2.1 Plan Objectives
Least-Cost Supplies — The goal is to acquire a long-term fixed price power supply that is lower
than any other market alternative.
Uncertainty (Risk) Reduction involves reducing future uncertainty and exposure to adverse
supply cost outcomes. Risks and mitigation factors include:
• Effectively matching load with supply reduces risk
• Diversifying supply resources
• Reducing regulatory risk (including the potentially adverse effects of structural changes
to the ERCOT market)
� Technological risk, and
• Economic risk
o Energy price and congestion price risks
o Transaction costs and execution risk
o Supply portfolio management operational risks
Additional renewable resource purchases will reduce the long-term cost volatility of Denton's
energy supply.
Diversifying supply sources by incorporating renewable resource technologies with different
production profiles reduces supply volumetric uncertainty across multiple timeframes (e.g.,
reducing volumetric variability by avoiding multiple wind resources with positively correlated
production profiles). Securing low fixed-costs for a substantial amount of supply resources,
while leaving open a portion of the supply portfolio to remain competitive, requires a delicate
balance.
Sustainability - the objective of sustainability covers several areas. It includes environmental
sustainability as well as the production sustainability of a generation resource. Stable
economics and minimal operations and maintenance ("O&M") costs contribute to
sustainability. Renewable resources offer superior sustainability because they don't degrade
over time and they require less maintenance, they require less regulatory and legal permitting
review, and they avoid potential carbon costs. Fossil fuel resources involve fuel adjustments
over time because of substantial fuel cost variability and the depletion of resources. Fossil fuel
resource technologies require more overhauling and maintenance compared to renewable
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 22
resources. Renewable resources use minimal water and emit no particulates, and other
polluting gases, compared to fossil fuels.
2.2 Customer Preference & the Competitive Market
A typical integrated resource plan includes identifying customer preferences and describing the
competitive market in which the utility operates. As mentioned previously, this resource plan is
unique because the customer preference for a power supply portfolio comprised of renewable
energy resources has already been selected.
With regard to competition, Denton doesn't have direct competition per se because it is a Non
Opt-In Entity ("NOIE"). Yet NOIEs need to stay competitive to the degree that they can avoid
pressure to open up to competition. Denton still needs to be sensitive to competitive
pressures, as the city is surrounded by competitive areas, and new ratepayers moving in to the
city will expect similar rates.
2.3 Efficient Management of a Renewable Resource Power Supply Portfolio
2.3.1 The Treatment and Management of Renewable Resources as an Energy Supply Hedge
Unfortunately, the track record of many public power entities in ERCOT regarding the efficient
management of renewable energy resources is poor. Many municipal utilities and electric
cooperatives have not done a good job with their power supply portfolio management in terms
of implementing renewables to offset load requirements.
The primary challenge is due to the intermittent nature of renewable resources. They are not
"dispatchable" in the sense of the traditional utility generation commitment and dispatch
process. Because they consider renewable resources as non-dispatchable, many of these
entities simply sell the output into the local market (local resource node pricing) rather than
manage around the intermittent production. This is termed "monetizing' the asset. But then
they purchase energy at a Hub or at a load zone to meet their load requirements.
This approach results in a double purchase because the energy has been purchased in the first
place via a power purchase agreement ("PPA"), which offsets future load requirements, and
then the renewable energy is sold in the market while market energy is simultaneously
purchased to serve load. This results in a less efficient three-step process (energy purchase,
then energy sale, then energy purchase) where inefficiencies and additional costs at each step
can add up to higher supply costs.
And this leaves the entities exposed to the substantial price risk of the uncertain locational
price differences between the Resource Node and the entity's Load Zone. Double purchasing is
almost always very costly and unnecessary.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 23
This is effectively treating the renewable resource as if it were a perfect financial hedge for an
energy consumer (offsetting the cash flow from floating price spot market purchases with the
cash flow from a fixed-price purchase made in advance), yet via a PPA the resource is effectively
a fixed-price physically-delivered forward purchase. It is more efficient to use the physical
delivery characteristics from the PPA as an offset to load requirements. This results in a more
efficient two-step process involving just the initial purchase from a PPA and then a second
balancing transaction (purchase of shortage or sale of excess).
An additional element to the successful management of a renewable resource power supply
portfolio is to complete the opposition hedge by financially tying resources to load via
Congestion Revenue Rights (��CRRs"). The pricing at the resource node for the physical
production from a PPA and pricing at the load are tied together through forecasts and
schedules matched with a CRR (an economic locational basis transaction). By using CRRs, the
two-step process is governed by the same type of basis transaction that is required in any
resource to load transaction in ERCOT.
Successfully achieving Denton's renewable resource goals involves several critical strategic
planning and tactical operational elements:
3. Location and production profile of the renewable resource(s)
4. Managing the supply portfolio by completing an industry best practice opposition
hedge, including:
o Forecasting resource output,
o Avoiding double purchasing (i.e., "monetizing" the renewable resource by selling
it into the market while simultaneously purchasing energy to serve load), and
o Managing basis (congestion) risk
Item 1 will be addressed as a result of the resource recommendations of this resource plan.
Item 2 involves the design of a daily supply balancing strategy, and the daily operational
guidelines and processes for supply portfolio management.
The key to efficiently managing a renewable resource power supply portfolio is understanding
(forecasting) when an intermittent asset is likely to produce, and counting that production as
supply to offset load, and then purchasing energy from the market only during those hours
when the intermittent resource is not likely to produce (and selling excess energy during those
hours where resource production is likely to exceed load requirements).
The technical definition of an opposition hedge is the establishment of one or more positions to
reduce financial uncertainty or risk from a floating price exposure (more detail on this concept
can be found in Appendix A— Hedging 101). In Denton's context, this involves the following
elements:
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 24
1. I��M����r�":�� u���;��r����i�w �►r "���a�ki� �'���� �r�i�.�c �x ������r�� - this results from its native
obligation to serve energy to its ratepayers. Unless it purchases fixed-price supplies of
energy in advance, Denton would be obligated to purchase energy in the ERCOT Day
Ahead ("DAM") or Real Time ("RT") markets at a variable cost to meet its obligation to
serve energy to its ratepayers.
2., "HedEinE" Denton's floatine nrice �� nc�,,rP with ? fixed-nrice urchase — this is
accomplished by purchasing electric energy to be delivered in the future at a fixed-cost
today through PPAs. This is a primary focus of this resource plan. A fixed-price hedge
established a known cost in advance avoids exposure to floating prices.
3. b-��� i�� � I����t�wn°s I+���ti�r��N ri�c�� �r� s���r� �ri1 R� �"Rf�� - to complete and perfect the
opposition hedge, additional transactions are necessary to translate or tie the pricing of
Denton's PPAs at ERCOT resource nodes to the pricing of Denton's load at its Load Zone.
This is accomplished through the use of ERCOT CRRs. As will be addressed in multiple
sections of this document, a power supply portfolio comprised of multiple and diverse
renewable resources results in a variety of delivery locations across Texas. CRRs will be
necessary to tie the pricing at various delivery locations to the pricing of energy in
Denton's Load Zone.
To summarize, a typical opposition hedge for Denton would include the following components;
1. A floating price exposure for Denton's load at its Load Zone (this is Denton's native
energy market exposure),
2. A fixed-price hedge(s) in the form of a PPA delivered to a Resource Node(s), and
3. A CRR hedge(s) to fix the price differential between a Resource Node and Denton's Load
Zone.
Of course, renewable resource power supply providers may offer PPAs that are priced at
locations closer to Denton, such as at a Hub or Denton's Load Zone. This could obviate or
reduce the need for CRRs to close the locational price gap. But this also introduces additional
supplier credit risk (contract replacement risk) into the evaluation equation. The greater credit
risk comes from how the supplier will provide a delivered price to a Hub or Load Zone. The
supplier is going to assume congestion risk, and if not managed properly, could jeopardize its
long-term financial viability.
Comparing the costs of renewable energy delivered to Denton's Load Zone or a nearby Hub to
the cost of energy delivered to a Resource Node is one of the primary cost evaluation factors of
this resource plan.
2.3.2 Managing a Renewable Resource Supply Portfolio in the ERCOT Market
An important goal and guiding principle for this resource plan is that the design and
management of a renewable resource supply portfolio must to take into account the structure
and conceptual design of the ERCOT market.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 25
ERCOT is an "energy-only" market. Load in ERCOT does not need to acquire and meet a
capacity requirement to ensure that adequate resources on the grid are available so that the
demand for electricity can be met at all times. The ERCOT market design requires that load
only needs to acquire adequate energy schedules, and most of the supply risk is then
neutralized.
In the ERCOT energy-only market, firming is not an explicit requirement. ERCOT automatically
"firms" inadequate supplies to meet all load requirements—the important risk management
focus is on managing the "firming" in a least-cost manner, both in terms of energy balancing
purchases/sales and managing congestion price risk.
In a bilateral market, utilities build and operate a generation portfolio and transmission grid to
produce and deliver power to loads in their service territories. In this type of market structure,
it makes sense to have a specific generating plant, as part of a diversified generation portfolio,
to meet variable demand requirements. If generation resources are intermittent, a power plant
that can be dispatched quickly to fill in the gaps in intermittent production is known as a
"firming" plant.
But in a power pool like ERCOT, specific power plants do not discretely serve local load. Rather,
generation resources are "pooled" to balance load requirements over a larger grid. The pooling
of generations assets results in several benefits, including reduced costs through more efficient
marginal dispatch of generation units, savings in reserve capacity requirements, more reliable
operation, and minimizing the adverse impacts of maintenance.
Thus, the intent of the ERCOT market design is that "firming" is accomplished using the entire
pool of generation assets, not by one or more specific plants in a local service territory. This
leads to a primary objective for Denton in the design of a power supply portfolio management
strategy where firming of renewable resources is managed in a least-cost manner through
forward and spot market purchases and CRR hedges.
The ERCOT market is designed so that generation is offered to the market and load
requirements are scheduled on a day-ahead basis. The market is intended for load and
generation to primarily participate in the DAM. Given the limitations and inherent error of
demand forecasting, and given a variety of other factors that can affect transmission capacity
and the availability of generation, ERCOT operates a RT market where it dispatches generation
resources based on economics and reliability requirements to meet system demand affected by
resource and transmission constraints. The RT market is intended as a balancing market, to
adjust for demand, generation and transmission uncertainties that cannot be completely
factored-in to the DAM.
Some load-serving entities in ERCOT rely on the RT as their primary source of energy supply
because prices are lower on average compared to the DAM. Producers often use this approach
because it requires less collateral than the DAM and they are typically credit-challenged
counterparties. On average, the DAM trades at a premium to the RT because it reduces risk
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 26
(i.e., revenue or cost uncertainty) and this risk reduction benefit commands a premium.
However, relying on the RT as a primary source of supply is antithetical to the intent and design
of the ERCOT market. ERCOT is designed for all generation and load to clear in the DAM, with
the RT being used to address imbalances.
In summary, the ERCOT market is designed for load-serving utilities without sufficient
generation assets to:
• purchase power in advance through PPAs
� schedule the delivery of the purchased power into the DAM
� purchase any short-term shortages / sell any short-term excess power in the DAM
• use CRRs to hedge
o Resource Node to Hub locational price differentials
o Hub to Load Zone locational price differentials
o DAM to RT price differentials
This resource plan is based on managing Denton's renewable resource power supply portfolio
in concert with the intent and design of the ERCOT market, through the use of industry best
practice risk management techniques and ERCOT-specific market instruments.
3.0 Information Gathering
This resource plan is based on an evaluation using a variety of types of data from multiple
sources. Where useful, specific examples of data and information are presented, along with
important takeaways.
Note — figure numbers in this document are based on the presentation order and may conflict
with an embedded figure number from the source document.
Information and data for this resource plan was gathered from a variety of sources, including
but not limited to Denton, ERCOT, the Texas Public Utility Commission, the U.S. Energy
Information Administration, the Chicago Mercantile Exchange and other industry sources.
Examples of key data are presented in order within separate sections based on the source.
Denton:
• Load
• Resources (capacity, production, contract start and end dates):
o Whitetail
o BlueBell
o Santa Rita
o Landfill
• DEC performance data (heat rate and variable operating costs)
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 27
Various Sources:
• The U.S. Energy Information Agency (historical spot natural gas prices and natural gas
production and consumption data)
•"Least-Cost Electric Utility Planning" Stoll, Harry G. 1989, Wiley-Interscience, ISBN-13:
978-0471636144, ISBN-10: 0471636142
� The Texas Public Utility Commission: various workshops and Rule Makings
• Texas Renewables website (ERCOT) Senate Bill 7 and Subsection (a) of Substantive Rule
25.173, Goal for Renewable Energy
• DAM, RT prices, and CRR market data from recent years
� historical heat rates
• market dispatch modeling
� resource adequacy studies
ERCOT information was sourced from:
• ERCOT website (ercot.com)
• 2016 ERCOT State of the Market Report
• 2016 Long Term System Assessment for the ERCOT Region
• ERCOT August 2017 Board of Directors Item 4.2.5: Grid Impacts of Natural Gas Price
Heat Rates
Figure 3-1 shows the implied heat rate and load relationship in ERCOT over the last three years.
Takeaway: the curve for the heat rate is almost the same curve that fits very easily over
multiple years. Heat rates are generally stationary. The progressive shape of the curve and the
relative heat rates don't change too much, because the units that are dispatched operate the
same way year after year. Extraordinary and lower probability events, such as hot weather or
transmission outages, such as in 2015, are necessary to get outside of the typical heat rate
curve. The heat rate of the DEC does not offer a competitive advantage in ERCOT and will
require lower probability and lower frequency events to warrant dispatch.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 28
Figure 3-1
45
40
�gure 13: Implied Hent R�te and Lo�d ,���1�����nship
4� 2014 2015 �' 2016
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25-30 30-35 35-40 40-45 45-50 50-55 55-60 60-65
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>65
Figures 3-2 and 3-3 show the ERCOT resource price stack at $4.50 per MMBtu and $2.50 per
MMBtu respectively. With an effective heat rate of approximately 10 MMBtu/MWh, the DEC's
dispatch cost would be about $45/MWh on the graph in Figure 2, and about $25/MWh on the
graph in Figure 3-3. The DEC dispatches later in the dispatch queue when gas prices are higher.
This is because there is an inverse relationship between natural gas and heat rates. The higher
the gas price, the lower the heat rate.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 29
Figure 3-2
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December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 30
Takeaway: if gas prices are $4.50, then coal-fired generation is dispatched first, before natural
gas-fired units. The DEC would be in a position to earn a high margin, but the number of hours
to earn that high margin is small. If gas prices are $2.50, then coal-fired generation is hardly
ever dispatched. The DEC would be dispatched earlier in the queue, but there would be very
little profit margin because of substantial competition with other gas-fired generation
resources.
ERCOT Expectations
Figure 3-44 comes from ERCOT's Long Term System Assessment ("LTSA")
Figure 3-4
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The LTSA is a composite study
made up of various processes and
analyses such as scenario
development, generation
expansion analysis, load forecasting
analysis, and transmission
expansion analysis.
The scenario-based planning
approach provided a structured
way for participants/stakeholders
to identify the most critical trends,
drivers, and uncertainties for the
upcoming ten- to fifteen-year
period. Scenario-based planning
considers sufficiently different, yet plausible futures and is used to evaluate transmission plans
across multiple future states.
Among their key findings are two that impact this resource plan:
• Load continued to grow in ERCOT in seven of the eight scenarios.
� All scenarios showed a significant amount of solar generation additions and the
retirement of coal and natural gas generation.
In addition to the ERCOT LTSA, this resource plan takes into consideration several studies and
recommendations for potential improvements in the ERCOT market. These are discussed in
Section 4.5 Regulatory Environment.
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�M�s' .man�c� �ath�r indus�r s��m����� power and fuel price data.
Figures 3-5 and 3-6 presents charts of current power and natural gas forward curves. Figure 3-5
shows forward prices as 12-month averages, while Figure 3-6 shows current forward curves
with monthly prices along with best-fit lines to better demonstrate overall values through time.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 31
Figure 3-5
Figure 3-6
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A variety of natural gas price curves were considered for use in the evaluation. Those used in
the Brattle Report ("Review of the Renewable Denton Plan") are generally much higher than
those from other sources.
Figure 3-7 shows the Brattle Base Case and Low Case compared #o the current NYMEX forward
curve. Although a forward curve for a commodity market like NYMEX is not predictive of future
prices, it is indicative of the clearing price that buyers and sellers are effectively recognizing as a
fair future value. Valuations using natural gas price projections should always include the
current forward curve as a reference case.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 32
Figure 3-7
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Figure 3-8 includes the last three years of U.S. Energy Information Administration ("EIA")
forecasts. Note the lower trend across the three years. The "HOG" forecast is their high oil and
gas production forecast.
Figure 3-8
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Figure 3-9 offers a somewhat different look at potential gas prices, combining historical spot
Henry Hub natural gas prices with the most recent confidence intervals. The confidence
intervals expand in the first few months because of higher volatility for winter futures months,
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 33
Figure 3-9
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The EIA Annual Energy Outlook is an important source for fundamental supply/demand data on
natural gas. EIA's expectations are for increased natural gas trade is dominated by liquefied
natural gas ("LNG") exports in the Reference case, which can be seen in Figure 3-10. The
increase in exports via pipelines and LNG represents an increase of approximately 4 TCF. This is
an increase of approximately 15%that does not have an historical precedence. In the past,
unexpected increases of demand of only 5% to 6% due to weather have caused natural gas
prices to double. This expected increase in natural gas exports is triple this amount.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 34
Figure 3-10
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Figure 3-11 shows expectations of increased natural gas consumption in most cases. These
analyses point to a potential for increasing natural gas prices, which could put upward pressure
on prices for renewable resources targeted by Denton. Longer term though, the substantial
overhang of potential supply increases from shale reserves, plus falling drilling costs, is likely to
produce a reversion to the long-term lower priced mean for natural gas.
Figure 3-11
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The following charts illustrate the price projections used in the economic evaluations in this
resource plan. Figure 3-12 shows natural gas price projections, Figure 3-14 shows power price
projections.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 35
The economic evaluations in this resource plan use four price scenarios including two from the
Brattle Report ("Review of the Renewable Denton Plan"), and two developed by ERC:
• ERC base case
• ERC high case
• Brattle base case
• Brattle low case
The Brattle report was missing a lower natural gas price case that represented the current
market environment. In other words, the Brattle report assume that natural gas prices would
only rise from the current environment. The ERC base case is important to add to the
evaluation mix because it adds a reasonable case that is lower than the Brattle gas price
projections.
The ERC base gas case is the linear extension of the current forward natural gas price (NYMEX)
as traded on the CME. The ERC high gas case mirrors the escalation and return to the mean
seen during the decade of the 2000s, as seen in Figure 3-13.
Figure 3-12
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December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 36
Figure 3-13
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Power price forecasts were developed using actual market heat rates over the last few years in
ERCOT at Hub North applied to the natural gas price forecasts. Multi-variable regressions were
used to reflect the negative correlation of natural gas to power. This produces a forecast that
recognizes the relationship that is part of the ERCOT economic dispatch: as natural gas rises
heat rates decline.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 37
Figure 3-14
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Load Scenarios
The following load scenarios were used for portfolio modeling:
1. A slightly negative growth rate
2. Mean annual growth of 1.6%
3. A high growth case of 3%.
4.0 Renewable Resource Plan Inputs & Analysis
4.1 Evaluation Factors
The evaluation factors are grouped around two of the resource plan objectives: 1) least-cost
and 2) reducing uncertainty (risk).
Regarding goal 1) least cost, Figure 4-1 presents a summary list of renewable resources that
have been considered for the renewable resource plan. These are grouped according to
primary technologies (e.g., wind, solar), secondary technologies (e.g., West Texas wind, coastal
wind), and geographic location.
The table in Figure 4-1 shows the expected ranges of prices at the resource node and then at
the HB�North. HB_ North is the resource delivery point for Denton. To transfer the resources
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 38
to the LZ_North, a cost in the basis is $0.75/MWh. These are the prices used to estimate the
costs of the supply. These costs are further adjusted as to profile. For example, a West Texas
wind and a Solar resource produce approximately 20% difference in revenue. Solar produces
during the higher priced on-peak hours while wind production drops off. Therefore, one would
need at least a 20% lower price for West Texas wind to compete with a Solar resource. If a
solar resource were priced at the North HUB at $25/MWh, a wind resource would need to be
priced at the same location at $20/MWh or less. There are also limits of any one type of
resource that can be placed into the portfolio given Denton's load shape. Additional resource
selections recommended in this resource plan take into account the resources that are already
in Denton's supply portfolio and scheduled for delivery. Denton will start receiving a large West
Texas wind supply in the spring of 2018 and a Solar resource in 2019. For this reason, the North
Texas and Coastal wind regions will be recommended as additions to Denton's portfolio. These
wind regions are farther away from the central West Texas wind belt that is located between
Abilene and Big Spring, Texas.
Figure 4-1
Resource Prices and Delivery Points
Solar
West Texas
Coastal
North Texas
South Texas
Panhandle
Delivery at Node
$22 to $2fi
$12 to $20
$22 to $31
$15 to $18
$21 to $22
$12 to $14
Delivery at HB North
$28 to $32
$19 to $25
$23 to $33
$18 to $21
$22 to $23
$20 to $23
Location
West Texas
West Texas
Texas Coast
North Texas
South Texas
North Texas
Regarding goal 2) reducing uncertainty (risk), the primary focus from the perspective of
evaluation factors for various renewable resources is on best-fit factors for Denton's energy
supply portfolio. These best-fit factors include the production profile match relative to
Denton's daily and seasonal load profiles, balancing the need for selling excess supply and
purchasing shortages, the quality of each resource's production, access to transmission
interconnections, and minimizing transmission issues with a particular focus on avoiding or
reducing congestion exposure.
4.2 Gap Analysis
A critical driver of the quantity of recommended renewable resources is how to quantity
Denton's target of 70% to 100% renewable power supply.
Although this can be defined from multiple perspectives, for the purpose of this resource plan
the definition of the amount of renewable supplies is the proportion of Denton's load that is
offset by renewable supplied over a given time period. Because of seasonal variations in load
and in renewable resource production, the most appropriate time period is a year. Thus, the
target will be a percentage of annual load in megawatt-hours ("MWhs").
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 39
Comparing the quantity in MWhs of Denton's planned resources with its load allows the
quantification of the gap that needs to be filled to meet renewable energy targets.
The reference year and target for increasing the amount of renewable resources in Denton's
supply portfolio is 2018, so the target amount will begin with this year.
Denton's annual load for 2019 is 1,550,000 MWh.
The gap that needs to be filled can be defined in more than one way. A major difference is in
the classification of the Whitetail PPA. According to data provided by Denton, the Whitetail
PPA was originally a 60 MW transaction for wind power. The original transaction was
subsequently modified, resulting in the conversion of the PPA to what looks like a conventional
energy "'round-the-clock" ("RTC") (24 hours per day for 7 days a week) product, a 30 MW RTC
transaction matched with renewable energy credits ("RECs"). The open question is this: should
the Whitetail PPA still be considered a renewable energy resource?
Several years ago, before renewable resource targets were exceeded in Texas, RECs offered
value as an incentive to develop more renewable resources, and could be used to "clean"
conventional electric energy when paired with conventional power transaction.
However, in the meantime, several factors worked together to undermine the value and
significance of RECs in ERCOT. Texas happens to be an ideal state for both wind and solar
generation. And with attractive PTC and ITC tax incentives, the falling cost and increasing
productivity of technology (e.g., photovoltaic cells), early targets for the expansion of
renewable resources were greatly exceeded, based mainly on least-cost economics, not
primarily on the economic incentives of RECs. Thus, RECs are no longer considered a viable way
to incentivize renewable development or to "green wash" convention generation resources so
that they would be classified as renewable resources.
The decision on whether or not to count Whitetail as a renewable resource is up to the
decision-makers at Denton, taking into account the optics and potential reputation risk for a
city with a substantial renewable resource target.
Figure 4-2 presents a listing of Denton's power supply resources.
Figure 4-2
Generotor Name Ty�a� LocaUon uC'��atiq}� �V47YhP"p Official Contract Date Stari Date End Date Annual Production
_
4Ad#tiit�l"�roI9(Nexteraj Wind WestTexas
Blue6ell Solar West Texas
°s�anft�� F�Gk�� Wind West Texas
�rad�fi0 Landfill Generation denton
ao ��'�,P�� �/i/ai iz/ai/z3 Zez,soo.00
30 �p"��"'�.'� 1/1/19 1/1/39 76,212.00
iso �/����� a/i/1� a/i/ae ssi,3oa.00
1.6 � 1/1/17 12/31/24 14,016.00
Counting Whitetail as a renewable resource leaves Denton at approximately 61% renewable.
Without counting Whitetail as a renewable resource results in approximately 44% renewable
resources.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 40
The recommendations in this resource plan will range in quantity based on the uncertainty of
counting Whitetail as a renewable resource. This leaves Denton needing between 9% and 26%
in additional renewable resources to meet its minimum goal of 70% renewable, or between
39% and 56% to meet the target of 100% renewable.
4.3 Production versus Load Profiles
One of the primary challenges in developing a renewable resource plan is the substantial
difference between the periodic production profile of various renewable energy resources and
Denton's load profile. This issue is not necessarily unique to renewable resources. Fixed-block
market purchases also exhibit a substantial difference compared to load, as the fixed-block
provides the same quantity for every time unit versus differing load levels for those same time
units. Only by purchasing a load-following contract (i.e., a contract that removes imbalances
between energy supply and demand in each interval of time) at a substantial premium to fixed-
block energy, can a production profile match that of a load profile.
As opposed to the mismatch of a fixed-block supply shape versus a variable load shape,
renewable resources present the challenge of mismatches between variable production profiles
and variable load profiles. These will be examined from both daily and seasonal perspectives.
4.3.1 Daily Profiles
Figure 4-3 shows ERCOT data with representative production and load profiles for a typical
summer day. Represented are production profiles for "Wind", which would be West Texas
wind, plus Coastal wind, Panhandle wind, and Solar. These are plotted against a typical
summer load profile for a load-serving entity with a substantial amount of residential and
commercial customers.
Takeaways:
• West Texas wind offers the worst match against load. The production increases during
less valuable, lower priced hours for energy.
• Solar and Coastal wind offer the best (on-peak) match against load, and can displace
market purchases of more expensive on-peak energy.
• Panhandle wind is somewhat superior to West Texas wind.
• Coastal wind production is at a low point during lower priced hours (i.e., it offers the
benefit of producing less when production is less valuable).
• Coastal wind and Solar have traditionally commanded a premium in terms of market
pricing, but with overall prices for renewable resources falling, the cost premiums
versus other renewable resources have compressed, making the assets more
compelling:
o Current low prices are attractive
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 41
o Their production profiles are a better fit for Denton's load, and are a better
complement to Denton's existing renewable resources such as Santa Rita (West
Texas wind), as opposed to adding more West Texas wind to Denton's supply
portfolio, or adding Panhandle wind.
Figure 4-3 - ERCOT Summer Renewable Production Profiles (source: 2016 State of the Market
Report for the ERCOT Electricity Markets)
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In addition to West Texas wind, Panhandle wind and Coastal wind, responses to Denton's
current request-for-proposals ("RFP") for renewable resources include wind resources in North
Texas and South Texas. The production profile of North Texas wind is similar to that of West
Texas wind. The profile for South Texas wind is between that of West Texas wind and Coastal
wind. A major difference is not the production profile but the timing coincidence of the
profiles. If they are far enough apart they may have the same profile but will not produce at
the same time of day. Lack of coincidence lowers the positive correlation of production and
lowers the likelihood of curtailment.
4.3.2 Seasonal Profiles
Continuing the theme of mismatched renewable resource production profiles versus Denton's
load profile, seasonal variations in both production and load profiles will require active portfolio
management to balance Denton's supply portfolio. Daily management will involve forecasting
renewable resource production and then transacting in the ERCOT DAM to sell power during
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 42
hours with excess supply, and purchasing power during hours with a supply shortage. The
optimal balance between excess and shortage is one of Denton's decision criteria for
determining renewable resource acquisitions and is discussed in Section 6.0 Reporting &
Summary Analysis.
Examples:
Figure 4-4 illustrates the daily supply/demand balance for a typical day in August. During this
season, wind output is typically low, while solar output is high (but not necessarily at its highest
during a calendar year), and the DEC has a higher likelihood of being dispatched. Specific
quantities of renewable resources are used for illustration purposes only.
The horizontal axis in Figure 4-4 represents the 24 hours of a day. The vertical axis is quantity in
Megawatts.
� Load is �i�ur� 4-4
_. _ .
represented as
the blue
horizontal
curved line
that looks like
a wave shape.
• Wind resource
saa
aoa
306
� 20U
� 106
Portfolio August Day Example
Low Wind
a�ar; r��r DEC
soo.o
Market
400.0 Purchase
s (salesj
300.0 Mc;oSolar
266,0
�tind
100.0
1�2 3 4 5,6 7 8 9 1' �� � Y�� ��� �°em¢�ro¢er�
OUtpUt IS 0 � � �� � � � - � , 0.0 �,�ti� ���an�
011 a� 17 18 19 20 2122 23 ��4 xc��ai xt:x;
represented by -�oo I--- I�106� �,�rket zrvt
the red vertical 1 °'F` x��
�zoo ezoo.a ����n :q�n.
bars.
� Solar resource output is represented by the green vertical bars.
• The DEC is represented by the light blue vertical bars.
• Market purchases are represented by purple vertical bars above the 0 level / market
sales are represented by purple vertical bars below the 0 level
Takeaways:
• Seasonally low wind output would necessitate market purchases during off-peak hours.
• The combination of solar production and DEC production could cause an excess of
supply during certain on-peak hours and would necessitate market sales.
Figure 4-5 illustrates the daily supply/demand balance for a typical day in April. During this
season wind output is typically at its highest, while solar output is modest, and the DEC is
unlikely to be dispatched. Again, specific quantities of renewable resources are used for
illustration purposes only.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 43
Figure 4-5
xso j
zo�
150
� �oo
�,
a � ,..
�i
-sa � �-
Portfolio April Day Example
Ha�h� wind
250.m �arkEt
���a,a:��
zoo.� Qa:�uesy
,.,,,��%s5ad�r
150.�
ioo.o uw �rr�Y�
�.�� r��Y��-�r���d
SOeO ��, � �;,�.
r���„��,p „
ovo w.. ..,
,x ,,,�� a�,�
As with Figure 4-4, the
horizontal axis in Figure
4-5 represents the 24
hours of a day. The
vertical axis is quantity
in Megawatts.
• Load is represented
as the blue horizontal
curved line that looks
like a wave shape.
• Wind resource output
is represented by the
red vertical bars.
• Solar resource output is represented by the green vertical bars.
• The DEC is represented by the light blue vertical bars.
• Market purchases are represented by purple vertical bars above the 0 level / market
sales are represented by purple vertical bars below the 0 level
Takeaways:
� Seasonally high wind output would necessitate market sales during off-peak hours.
• The combination of only modest solar production and lack of DEC production could
cause a shortage of supply during certain on-peak hours and would necessitate market
purchases for supply/demand balancing.
4.3.3 Quality of Specific Renewable Resources
Another critical evaluation factor is the quality of specific renewable resources. As can be seen
in Figure 4-3, the "quality" of wind differs depending on the Iocation. Panhandle wind tends to
have a higher capacity factor than West Texas wind. Coastal wind offers much greater on-peak
production than Panhandle and West Texas.
The location of wind resources also affects the quality of the output in terms of the consistency
of the direction of wind and the lack of wind turbulence.
The location of solar affects the degree of power output relative to a given type of photovoltaic
("PV") cell.
Location also affects the ability to connect to the ERCOT grid in an economically efficient
manner, as well as the potential impact of additional costs in the form of charges for
transmission congestion.
These location factors are discussed in the following sections.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 44
4.3.3.1 Producer Production Data Bias
An important consideration in evaluating renewable resources is to verify and correct
production output claims of renewable resource developers. Both solar and wind developers
typically include a bias to expected performance. Producers typically over-estimate the
efficiency of their installations to attract investors. They often used idealized models that
overlook important details. For sellers of renewable resources, this outcome is not a surprise.
A good analogy is the miles per gallon ("MPG") claims for new cars. They can be achieved
under specific and idealized circumstances, but everyday driving rarely achieves the promoted
MPG. Something similar occurs with renewable resource developers.
Wind producers cannot predict wake effects well, and typical amounts of reduction (correction)
to developers' claims are on the order of 5%to 8%.
Solar developers often use average values that do not reflect hourly temperature effects, for
example, the warmer the ambient conditions, the poorer the PV performance. This can reduce
actual performance by 15% or more depending on the equipment type and installation design.
To adjust for these biases, independent data from the National Renewable Energy Laboratory
("NREL") and ERCOT was used in this resource plan. NREL tools allow verification by specifying
what type of PVi cell is involved, along with the tilt of the PVi cells mounts, including fixed, single
or dual axis mounting. These tools can be used to produce hourly production curves for various
seasons and at various locations across the state.
For wind resources, ERCOT has an extensive database of wind production profiles across the
state.
Using these sources of independent data, the following output reductions have been calculated
for Denton's current renewable resources (Whitetail is not included because it has been
converted to a fixed 30 MW RTC block) in Figure 4-6:
�-��ure 4-b
w�www. �.. _ ..............��...��
Original Revised
Production Production
Denton Estimate Estimate Reduction
Resource (Annual MWhs) (Annual MWhs) (Annual MWhs) Reduction
Santa Rita 643860 591300
52560 8%
. �.�a..�......��� ....................��... a
Bluebell 81468 65700 15768 19%
.�_.� ............................._.......�.�................. ...._..�M
�.�_�_�.�......._����.�...........I.�� w...........� .............��� ��...���......._
68329 (4.41% of
Total Reduction �, load)
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 45
4.3.3.2 Wind Location Considerations
Figure 4-7
There are at least six different wind regions in
ERCOT that are not well correlated because of
the distance between them. Because Denton
owns a large resource in West Texas, other
regions will need to be considered.
Both Panhandle and Coastal wind resources
are not well correlated with System-wide
output.
As previously mentioned, coastal wind is
superior to other types of wind due to a higher
capacity factor and greater production during
more valuable on-peak hours.
Wind resource capacity factors are often over estimated because it is difficult to include site-
specific losses due to wind shift turbulence and topographic effects. Wind turbines in the wake
of other wind turbines suffer from reduced output. A natural illustration of this effect is in
Figure 4-7.
Figures 4-8, 4-9 and 4-10 illustrate three different locations of wind resources. Figure 4-8
shows wind resource and directional diffusion for a wind farm near the Texas/Oklahoma border
(Borger), Figure 4-9 shows the output for a wind farm near Abilene, and Figure 4-10 shows the
output for a coastal wind resource.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 46
Figure 4-8
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A tighter diffusion pattern and a more consistent wind direction are prefer.able for more
consistent output and a higher capacity factor.
Figure 4-9
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This factor supports the choice of Coastal wind.
Figure 4-10
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 47
Additional coastal wind factors include the following:
w
�w Less correlated with ERCOT System wind, producing higher output during the summer
afternoons.
• Lower congestion risk with lower output during the spring and fall when high West
Texas Winds increase congestion.
• More reliable for forecasting because it depends on the land, ocean effect.
• Coastal wind resources in the ERCOT South Zone are away from resources built in West
Texas, and they are closer to potential retirements of generation in East and South
Texas.
C�i��d�r�nt���� �fi ��a��t�l �air��:
• Coastal wind PPAs usually command a cost premium compared to other wind resources,
• Coastal environmental considerations (e.g. hurricanes, sensitive habitat).
• Subject to build restrictions (e.g., near U.S. Air Bases).
• A great deal of additional load being added in the area.
Despite these disadvantages, the advantages of Coastal wind, especially regarding the fit to
Denton's supply portfolio, outweigh the disadvantages.
4.3.3.3 Solar Location Considerations
Solar irradiance (the power per unit area received from the Sun) as a function of location is a
primary evaluation factor for solar renewable resources.
Solar irradiance is impacted by latitude, potential for cloud cover, and temperature factors.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 48
Figure 4-11 presents an overview of solar irradiance„
Figure 4-11
Figure 4-12 shows a map of rainfall in Texas. Rainfall is correlated with cloud cover, which
reduces solar output.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 49
Figure 4-12 Rainfall in Texas
��a� ���,�y���e��?wwwU�.�A��a>u�
Temperatures are also a factor. High
temperatures instigate atmospheric
convection which causes less energy to reach
the ground, thereby reducing solar output.
Warmer temperatures also raise the
temperature of PVi cells driving down
efficiency.
Typically, the month ofJune has more solar
production than in August, not because it has
longer days and a higher sun angle, but
because August is usually hotter. Sometimes
the month of May can be better than June
because of higher temperatures in June.
For optimal irradiance, the best location in
Texas for solar would be all the way west to EI Paso, but that's outside of ERCOT. Another
limiting factor is congestion —going too far can entail too much transmission congestion. An
optimal location representing a balance of sufficient irradiance, limited cloud cover, and
manageable congestion would be close to Midland, Texas.
4.3.3.4 Additional Location Considerations
An important consideration for evaluating
optimal resource locations is the projection of
generation additions and retirements in ERCOT.
With more renewable resources expected to be
developed, and with conventional resources such
as coal-fired generation expected to experience
increased retirements, congestion issues may be
exacerbated.
Figure 4-13
;�;J�,���;
�,,,;
, �,
,„ ,
�t� �
�'��n, , � ���.,,
rd�,
� `,,
Periodically, ERCOT conducts a long-term system �;� �
assessment. Data from ERCOT's "2016 Long-
Term System Assessment for the ERCOT Region , ���n ����
„ ���A���� �:,
shows a projected increase in generation in the �" �
West and a decrease in generation in the East.
This can be seen in Figure 4-13. Yellow to orange
circles indicate generation additions, while blue
circles indicate projected retirements. This will
create a decisive West to East flow of production. In considering resource additions, Coastal
wind is not facing heavy competition. Adding resource capacity in an area with retiring
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 50
conventional generation, and closer to load than the majority of renewable resource additions,
presents several advantages.
Optimal site selection is more limited for solar however, due to the need to maximize irradiance
while minimizing rainfall and cloud cover. Although there is some solar production in the
southeast of Texas, irradiance isn't very good in that region.
Figure 4-14 (source: ERCOT)
4.4 Congestion (Location Basis) Considerations
Another location consideration is
the access to transmission. Pricing
points cluster at wind resources
near big substations and 345 kv
interconnects. The location for
renewable resources shouldn't be
way out in the middle between
the pricing points as illustrated on
the map in Figure 4-14. Ideally, the
better locations are in between
the pricing clusters and urban
areas, east of the clusters in the
western region, and along the
coast closer to Corpus Christi than
Brownsville.
Congestion hedging is an important component of completing the opposition hedge, and of
carrying out an efficient internal portfolio management operation for renewable resources, as
discussed in Section 2.3 Efficient Management of a Renewable Resource Power Supply
Portfolio. Congestion hedging is like insurance - it is important to insure exposures in a
complete manner.
ERC's extensive experience with CRR management and hedging for several clients indicates that
not only is the net cost of congestion hedging acceptable, but CRRs often pay for themselves
when exposure risk increases. Notice in Figure 4-15 that when congestion rent in the DAM
increased in 2016, the payment to CRR owners exceeded CRR auction revenue. And in addition
to congestion rent in the DAM, the total congestion costs experienced in the ERCOT real-time
market in 2016 were $497 million, an increase of 40 percent from 2015. Transmission outages
were the primary causes for this increase.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 51
Figure 4-15
�gure 52: CRR Auction Revcnuc, Payments �nd Congestion Rent
590 ,�y . �, ,�,�� �, ,,. . — e..
$80 Payment
�Co���s��
$70 ��'�c�!%%%%
.��aa��Cau��r l
$ 60 Payment
c $50
0
? $ 40
$30
$20
$10
$0
iJ/i�
������,11{�t%J ;
$320 milion �Auction Revenue
�wners: $369 milion ""' �CRR Paymeni .�...
Otongestian Rent
S408 million'
%//�%f�tf �;
5346 milion
Dwneis: �258 milion __
5300 million
C � �- � L T C `. 00 Q I +" � 7 � C � T C f b0 Q �'' i �
la Q � �< 7 67 � O I� 07 � I n R� 7 t.-�� 7 C/ � O
; LL��a,�, �',a �+io�z�o ��-%g,al�;,,, a� o Z o
2015 2016
The use of CRRs should not be avoided because of possible curtailments or derations. In fact,
the principal hedging method in the market to limit curtailment risk is the purchase of a CRR. A
CRR will make the owner indifferent to curtailment because it will fix the price between two
points. This is an economic hedge. It is anticipated that curtailments will rise, but will remain
modest in most wind regions, as shown in Figure 4-16.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 52
Figure 4-16
6
5
t
3
�
c 4
0
«
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d
c 3
�
v
c
3
2
1
0
�igure 65: Wmd 1'�r���r�i;a�� and Curtsilment
Derations are local and less than 3% of the CRR market as can be seen in Figure 4-17.
Figure 4-17
$70
$65
$60
$55
N $50
c
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�
« $40
c
a
�, $35
m
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u
$25
$20
$15
$10
$5
$0
Nigure 53: CRR Shorlfa�s and Derations
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 53
The data in Figure 4-18 shows that congestion hedging with CRRs is a mainstream activity in the
ERCOT market. The chart shows the volume of CRR hedging activities brought into the RT
market via Point to Point ("PtP") congestion hedges, as represented by Net System Flow. The
Net System Flow exceeds the volume of purchases in the DAM and is more than the average RT
load. Figure 4-19 shows that in two of the last three years, revenues from PtP obligations
exceeded charges. Informed marketers use CRRs and PtPs to limit their basis risk for their
energy portfolios. As can be seen in Figure 4-15, the payment to CRR owners is greater than the
cost of ownership. The exposure (basis risk) is higher than the CRR costs. This means that the
non-congestion hedging load is paying congestion rents to loads with CRRs. That is where the
revenue comes from to pay for any imbalances caused by claims from the CRR owners.
Figure 4-18
�o
60
� 50
v
E
�
j 40
a
Y
�
N
� 30
m
a
t
a
� 20
0
10
0
l�gure 27: Volume of Day-Ahead Market Activity by Hour
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 54
Figure 4-19
N�gure 28: Poin�--�a�-�'*����w� Obligahon Charges and Revenues
$1 zo _.. ....,,,, �.m� _
�Day-Ahead Charge � �
_ . _. _ (i��,�� %�
c $100
0
�
N
C �a�
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T
(0
d
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'o
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«
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2014 , 2015 2016
4.5 Regulatory Environment
The potential for changes in ERCOT is another factor in the resource plan analysis. ERCOT
continually changes the way the system operates. For example, the following studies and
recommendations for several potential improvements to the ERCOT markets that appear in the
2016 ERCOT State of the Market Report:
1. Evaluate policies and programs that create incentives for loads to reduce consumption
for reasons unrelated to real-time energy prices, including: (a) the Emergency Response
Service (ERS) program and (b) the allocation of transmission costs.
2. Modify the real-time market software to better commit load and generation resources
that can be online within 30 minutes.
3. Implement real-time co-optimization of energy and ancillary services.
4. Price future ancillary services based on the shadow price of procuring the service.
5. Ensure that the price of any energy deployed from a reliability must run (RMR) unit
reflects the shortage conditions that exist by the fact that there is an RMR unit.
6. Evaluate the need for a local reserve product.
7. Consider including marginal losses in ERCOT locational marginal prices.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 55
It is not known if any of these improvements will be adopted soon, or ever. Each one has a
potential effect on the recommendations for Denton's renewable resources, although
mitigating actions aren't available for all of them.
An example is the proposal to change the market design to incorporate marginal line losses.
This will add costs to resources that are farther from load zones. A change in the ERCOT market
design to incorporate costs associated with marginal line losses would favor Coastal and North
Texas wind resources because they would be closer to a load zone. These two wind resources
would reduce the potential risk from the adoption of marginal losses, and CRRs would still be
available to mitigate the risk to some degree.
5.0 Renewable Resource Portfolio Model Development
5.1 Modeling Factors
The following is a list of variables considered in qualitative and quantitative modeling:
� Naturat gas prices
• Power prices
• ERCOT Hub North heat rates
• DEC heat rate and estimate of variable O&M
• Denton load growth
• Renewable resource production profiles
• Renewable Prices
• Basis costs (CRRs and locational basis floating price exposure)
• CRR prices, Point to Point prices
• Regulation changes (e.g., incorporation of Marginal Losses, Local Reserves, potential
federal Solar tariff)
• PTC and ITC effects on supply and prices (curtailment frequency)
• Coal and natural gas plant retirements
• Renewable saturation in certain regions
• Lubbock ERCOT integration
• Proposed new resources
5.2 Portfolio Modeling
[,���°r�gN���'m�aN� An�wN s�s (�„ia��r��i����t�i�n�
An important aspect of modeling portfolio costs and developing a portfolio mix that meets the
twin resource plan goals of least-cost and uncertainty (risk) reduction is to achieve as much
diversification as possible in the supply portfolio.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 56
One important measure of diversification is the correlation of various renewable resource
production profiles. A portfolio comprised of renewable resources that are highly positively
correlated would suffer from a lack of diversification. When one resource would not be
producing, other resources would also not be producing. The goal is to assemble a portfolio
with a mix of less correlated resources so that the overall portfolio production is more
consistent. An excellent example of this is the match between Solar and a traditional wind
resource like West Texas wind. West Texas wind typically produces more during off-peak
(nighttime) hours and produces very little during summer on-peak hours (daytime), whereas
Solar production is not existent at night and ramps up during the day, peaking during some of
the most highly-priced on-peak hours.
Combining renewable resources with lower correlations reduces risk and improves overall
supply portfolio correlation with Denton's load, and it improves forecast reliability. The main
risk reduction is the combination of solar resources and wind resources. A typical correlation
between the two ranges between -70% to -95%. Wind resource combinations have varying
correlations due to differences in quality (e.g., higher capacity factor Coastal wind vs. West
Texas wind) and location (e.g., West Texas vs. Panhandle). Very few commodity portfolios have
the opportunity of such advantageous pairing of assets.
An additional diversification factor is the location of resources especially in regard to
congestion exposure. Diversifying the supply portfolio reduces overall congestion risk exposure
and also contributes to more consistent economic performance. An example is avoiding having
all of Denton's renewable resources in the western part of ERCOT because it is the region with
the highest congestion risk, second only to the Panhandle region.
[�.�a�w�ki��tiv� l��a�rr�ac.h
Portfolio modeling was based on a blend of correlation analysis and scenario valuation. Various
mixes of renewable resource quantities, constrained by the results of the correlation analysis,
were valued according to the ranges of natural gas and power price projections, along with
related DEC dispatch scenarios, with the objectives of finding the least-cost portfolios with the
lowest cost variability.
The production profiles of various renewable resource were screened to determine how the
profiles performed against historical prices. This involved calculating the balancing costs for
each profile to determine the net effective cost of each resource type. Balancing costs are a
blend of spot market purchases of market power when renewable production fell short of load
requirements, or DEC production when the DEC was a lower priced alternative to DAM
purchases, and spot market sales of excess power when renewable production exceeded load
requirements.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 57
5.3 Portfolio Optimization
Introduction
An additional analytical technique can be applied to confirm the recommended selection of
renewable resource assets to Denton's energy supply portfolio: portfolio optimization.
In addition to the benefits of a 100% renewable energy supply, Denton will benefit from the
reduced cost variability of a well-diversified supply portfolio. Diversification is achieved with an
optimal mixture of resources so that the power supply portfolio performs with the lowest risk
while meeting Denton's power supply risk management objectives.
Quantifying the optimal resource mix is accomplished by measuring the returns, and the
variance and covariancel of the individual resources, over an appropriate period of time. In
other words, this approach optimizes the asset mix of a portfolio based on the periodic returns
of each resource, the volatility of each resource, and the correlations between resources.
This is a widely accepted approach to portfolio design following the Modern Portfolio Theory
("MPT") developed by Harry Markowitz (who won a Nobel Prize for developing MPT). MPT is a
theory of optimal diversification; based on historical data and measures of asset returns, risk
and correlations, MPT selects the optimal diversification portfolio mix.
MPT is used to model portfolios with the aim of maximizing expected portfolio return for a
given amount of portfolio risk. The objective is to select a proportional combination of assets
that collectively has lower risk than any individual asset. The lower portfolio risk is achieved by
the lack of perfect correlation among the assets.
Portfolio optimization can be used to measure the optimum percentage weighting of each
prospective asset in a portfolio. It balances the risk of the individual assets with the return for
each asset. Typically, higher return assets are riskier (i.e., they have a higher variance or
standard deviation of returns). Additionally, an asset's correlation to other assets will
determine the best fit in a portfolio. The optimization allows the portfolio to measure the
tradeoff between the riskiness of an asset with the return of that asset and the fit of each asset
in the portfolio.
The optimization model used for the City of Denton's renewable portfolio was developed by
Robert F. Stambaugh of the Wharton School of Business —The University of Pennsylvania
f�.��� /�i�i���nc�.wr�h��t.a¢�.�a �r��.��������nrmb�u�����t� h�rr�.N.�.•
The user can select different levels of assets in the portfolio. For the purpose of this analysis, a
three-asset portfolio was assumed. The reason for this assumption is that Denton has already
purchased two renewable assets: Santa Rita Wind and Blue Bell Solar. This has limited the
1 Variance is an intermediate step in calculating historical price volatility, and covariance is an intermediate step in
calculating a correlation coefficient.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 58
choices that can be made to fulfill the renewable goals of 70% and 100%. The choices are now
limited to the incremental amounts to reach those goals.
In the input, the following numerical identifier represents the renewable assets under
consideration to fill the renewable goals. The optimization goal is to give some guidance as to
the relative percentage to add to the portfolio through solicitations to the market. Denton will
have only those choices that the market offers. There is a common misperception that the
RFPs can ask for terms and conditions that are not non-standard and the seller must respond.
Extensive experience with successful RFP's shows that buyers should craft their solicitations
around standard and transparent terms and conditions, and this results in a lower purchase
cost for the buyer.
The three assets under consideration in the optimization;
1. Solar Asset
2. Santa Rita Wind Asset (West Texas type wind)
3. Coastal Wind Asset
The return, standard deviation, and correlations for each asset can be found in the input table.
These were measured using ERCOT prices to calculate an hourly market cost for each asset's
hourly production. Renewable production was used to calculate each asset's profile cost using
the price of the resource. The two cost matrices were subtracted and this created a net
revenue profile matrix for each asset. The renewable asset average returns were calculated for
a year for each asset type. The test year used in these simulations was 2014. Other ERCOT price
years were tested and yielded similar results.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 59
Figure 5-1 Portfolio Optimization Input Table
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Note that there is a hierarchy of outcomes that explains the strong preference of solar to the
other two assets, and the preference of Coastal type wind to West Texas type wind profile and
cost. This is the relationship that the higher return assets are also the lowest standard
deviation assets. This runs counter to typical assets like stocks and bonds, where typically the
highest return assets also have the highest standard deviation of returns. Once this
relationship is identified, the outcome is expected. The optimization will choose the lowest risk
asset with the higher return. Solar produces during the day, especially during the on-peak
hours where the returns from a fixed price hedge are higher. Coastal type wind also has a
significant on-peak production profile when compared to West Texas wind.
Model Outcomes
The model asks for a risk aversion coefficient for Denton. The selection was to choose an
average coefficient of 2(see Figure 5- 1). Risk aversion is required for the model input, and in
portfolio theory it measures the outcome compared to the risk-free rate (i.e., typically the rate
of a 1-year U.S. Treasury Bill). This is not germane in the selection of energy supply portfolios,
and increasing and decreasing the coefficient did not change the outcomes in this three-asset
model.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 60
The model shows that Solar comprising 35% (additional 200 MWs) or greater is always selected
(see Figures 5— 2 and 5- 3). The label "Initial Weights" are shown in each table and the
optimized model outcome percentage weights are listed under the label "Final" weighting
table.
Figure 5— 2 Upper Bound Limits for Solar and West Texas Wind
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Texas wind
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The outcomes show that unless (limit the upper boundary) the amount of solar is constrained,
the weight of Solar would reach 67% as seen in Figure 5- 3. This would produce too much solar
for Denton at around 400 MWs. The expected on-peak hedged level would be approximately
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 61
275 MWs considering all of the current and proposed assets in the portfolio. Limiting the
outcome to 200 MWs produces a weight in the portfolio of around 35%. Limiting the outcome
for West Texas wind via the lower boundary is also needed, otherwise the optimization would
choose 0% (see Figure 5- 3), and this would not reflect Denton's commitment to Santa Rita.
The portfolio optimization model selected additional Solar and Coastal type wind to be added
to the portfolio. It does not select other types of additional wind into the portfolio.
5.4 Demand Response Side (Demand-side Management)
ERC strongly supports and advocates Demand Response and Demand-side Resources. These
include residential, commercial and institutional solar, community solar, ERCOT's Emergency
Response Service ("ERS") program, and battery storage. Storage is particularly intriguing
because the lack of it is one of the main distinguishing characteristics of electricity as a
commodity, and is one of the main drivers of electricity's high price volatility. The industry is
just on the cusp of commercially viable battery storage, in terms of battery performance
capability and cost.
This resource plan and its supply portfolio modeling does not incorporate the potential benefit
of demand-side renewable resources for the present, although demand-side resources will be
an important part of the future.
In the compressed project timeline for this resource plan, the best course of action is to follow
the Pareto Principle (aka the 80/20 rule) and address the small set of issues/variables that will
have the greatest impact on Denton's goals. The primary focus in this resource plan is on the
issues that will have the greatest near-term impact and benefits for Denton.
The main issue is that Denton is facing near-term critical path issues and multiple risk factors in
the present and near future regarding renewable resources. The fuse has already been lighted
on a renewable resource acquisition strategy, and specific large-scale issues must be addressed
in short order, including the initiation of delivery for a large wind PPA in early 2018, and near-
term purchase decision deadlines taking into account the lead time necessary in securing PPAs
for renewable resource projects to meet Denton's initial goal of 70% renewable resources.
An immediate gap analysis was needed to identify best-fit renewable resources to achieve as
much diversification as possible in Denton's supply portfolio. And this resource plan played
catch-up with a RFP process for renewable resources that was already underway. Other near-
term issues that demand primary focus in the compressed evaluation timeframe include the
potential for a federal tariff on imported solar PV panels, the uncertain future of low renewable
resource prices in the wake of announced curtailments of conventional generation, and the
pricing effect of the scheduled reduction and eventual elimination of federal tax credits.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 62
Critical path issues also include developing the operational process requirements to optimally
manage a renewable resource power supply portfolio in order to avoid the substantial risks of
suboptimal and inefficient portfolio management.
As mentioned previously, Demand Response and other demand-side management programs
and assets have an important role to play, and will benefit from a longer timeframe for planning
and decision-making. How a utility chooses to incentivize demand-side resources in order to
reduce and not increase operations risk requires careful coordination with rate design. For
example, some utilities have found that limited penetration of residential solar is the best fit for
portions of its distribution system, and thus require irradiation studies to target optimal
rooftops within neighborhoods as well as a rate incentive mechanism designed to cap roof-top
solar at acceptable levels.
Demand-side distributed generation also requires careful planning based on potential ERCOT
interconnection requirements, special NOIE reporting requirements, Resource Entity
registration, and specific metering requirements.
Careful consideration must be given to the cost impacts of demand-side resource development.
Storage is an intriguing option, but it is just now on the cusp of commercial viability. Figure 5-1
represents a typical adoption curve for new technologies. Enormous increases in battery
storage capability (storage capacity and duration) and substantial decreases in cost will occur as
the technology transitions into the Early Majority stage. At present, the technology is in the
Early Adopter stage. Denton should carefully consider the cost impact of early adoption. A
useful example is Austin which has been an early adopter of renewable resources, and has high-
priced wind and solar resources in its portfolio. Current prices for wind resources are in the $12
to $22/MWh range, and solar resources are in the mid-$20/MWh range, whereas just a few
years ago wind prices were offered between $40 to $65/MWh and solar was as much as 5 to 7
times the price of current offers. Austin's Webberville solar project has a cost of $165/MWh.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 63
Figure 5-4
Penetration of
Target Market
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A potential offset to early adopter cost premiums could be financial assistance from the Texas
Emissions Reduction Plan ("TERP") program which offers financial incentives to local
governments, among other entities, for new equipment that contributes to pollution reduction.
They have several grant programs including a New Technology Implementation Grant ("NTIG")
program to "provide incentives to assist in the implementation of new technologies to reduce
emissions of pollutants from facilities and other stationary sources." More information can be
found at q�t��rs:�'/r�w�=tc��:t��a�� �rav�'�ir�a����ty�°���°��.
Demand Response programs and other demand-side resources, with careful planning and
design, can make a useful and important contribution along the timeline as Denton moves from
its near-term goal of 70% renewable resources up to its longer-term goal of 100%. An
additional discussion of this subject is in the "�r�c�u�l �wc�'c� ����,���th"° portion of section 6.4 The
Path to 100% Renewable Resources.
6.0 Reporting & Summary Analysis
6.1 The Denton Energy Center
The DEC will play a role in Denton's renewable resource portfolio as a cost hedge during certain
super high-priced hours.
As discussed previously, the greatest challenge in managing a power supply portfolio comprised
of renewable energy resources is balancing the supply portfolio around the intermittent
production of renewable power plants.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 64
Balancing the supply portfolio is often referred to as "firming" inadequate supplies. As
explained previously, in the ERCOT energy-only market, firming is not an explicit requirement.
ERCOT automatically "firms" inadequate supplies to meet all load requirements — the important
focus is on managing the "firming" in a least-cost manner, both in terms of energy balancing
purchases/sales and managing congestion price risk.
The results of the quantitative modeling employed for this resource plan show that the DEC
should not be the sole resource used to "firm" a renewable resource portfolio. Using the DEC
as a sole hedge is not the least cost and lowest risk option for over 75% of the hours in a year.
The low heat rate associated with most of the hours in the DAM will allow Denton to firm
intermittent renewable production with spot market purchases at a lower cost than the DEC
while avoiding congestion and price risk.
According to DEC performance data provided by Denton, the DEC variable cost at today's Heat
Rate is 9.7 MMBtu per MWh. This assumes an 8.3 fixed heat rate at the high sustained limit
and variable operating costs of $3.8 per MWh. At current natural gas prices the variable cost
translates to a 1.4 heat rate.
As can be seen in the ERCOT resource price stack data in Section 3.0 Information Gathering,
many hours of the day are likely to be below the effective heat rate of the DEC. For example,
considering the ERCOT load and price projections used for this resource report, at a marginal
heat rate of 8 and natural gas prices of $3 per MMBtu, a market price of $24 per MWh would
be available for purchases to supplement intermittent renewable resource production.
Because this is lower than the expected cost of the DEC, a market purchase at Load Zone North
would be made to balance Denton's portfolio. The DEC would not be used to hedge this risk
because it would result in an increased supply price of over 1.7 heat rate or $5.10 per MWh
before the Dec would dispatch.
The cost of dispatching the DEC and not using market purchases to hedge the supply risk could
produce an increased cost of over 20%. The Dec cost would be 9.7 heat rate at a$3 gas price
($29.1/MWh) versus a DAM price of an 8 hear rate at a$3 gas price ($24/MWh).
In addition, the DAM is a fully hedged price, whereas the DEC would include the potential of
basis loss because the DEC would need Point to Point purchases that match exactly the energy
amount consumed by Denton in the RT. Because the dispatch is unknown, the Point to Point
would have to be purchased against an energy dispatch. A DAM at Load Zone North does not
need the purchase of a Point to Point basis hedge. It would settle the resource CRR in the DAM.
And note that this is a conservative difference because of the ramping and effective heat rate
of the DEC will be higher than the 9.7 heat rate until the DEC is running long enough to reach its
high sustained limit.
An example of when the DEC would be dispatched rather than using DAM purchases to hedge a
supply shortfall is in Figure 6-1. During a peak demand month such as August, the DEC might be
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 65
dispatched about half of the time (the periods of time without the green shading). But in this
example, even in a month like August, using the DEC as a hedge is likely not to be the least cost
and lowest risk alternative for approximately 50% of the time. Figure 6-1 also shows that
during DAM purchase hours (the hours shaded in green) the difference between the DAM fully-
hedged price and the variable RT price is negligible (average of $0.44). Participating in the RT
would be a large disadvantage to Denton because of higher risk but little-to-no benefits. This
begs the following question — is taking the higher risk in the RT worth saving the 44-cent
difference? Conservative hedgers and risk managers would answer that question with a
resounding "no!".
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 66
Figure 6-1
Slao.00
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$80.00
$60.00
$40.00
$20.00
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Advantages:
• The DEC is a heat rate hedge (note that it is not an energy cost hedge unless the price of
natural gas is fixed)
• It will reduce cost risk for Denton because at certain times it will be dispatched during
price spikes.
• It also provides a long-term hedge benefit in the event of accelerated retirement of
conventional fossil fuel generation resources in ERCOT that may elevate heat rates.
Disadvantages:
� As a higher heat rate generator, it offers no pricing power and offers no competitive
advantage.
� ERCOT manages the system so that heat rates don't vary much (see Figure 1)
� Its value to Denton requires that natural gas prices go up substantially in the future.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 67
Additional Alternatives for Ex�r�a�t�i�� V�I�� fr��� t��a� ��,�C�
Based on the last bullet point under disadvantages, Denton should be prepared to sell
DEC output forward when or if there is a spike in natural gas prices. Natural gas prices
tend to revert to the long-term mean after price spikes, so that increased value due to a
price spike may be transitory and should be taken advantage of.
The DEC can be used to sell firming services to other organizations looking to add
renewable resources. This can mean that the DEC is not used as a producing generator,
but as a contingent financial hedge (i.e., the actual dispatch and fuel use may be
unchanged but the revenue from the resource will be increased). This is because at the
time Denton might be obligated to provide firming energy, market purchases are more
likely than the DEC to be the least cost alternative.
As previously discussed, because of the mismatch in seasonal production profiles of
renewable resources versus Denton's load profile, there are likely to be periods of time
when Denton will have excess supplies (e.g., in the Spring). It may be beneficial to sell
excess renewable power during these periods using the DEC to firm the transaction.
Takeaway: The DEC will serve a role as a supply cost hedge to firm Denton's renewable
resource portfolio, but based on the financial evaluation in this resource plan, the majority of
firming the supply portfolio will be more economically efficient through purchases in the DAM.
Denton should look for opportunities to sell a portion of the DEC forward during natural gas or
heat rate spikes, and for opportunities to sell firming services or to firm sales of excess
renewable supplies.
6.2 The Benefits of the Denton Renewable Portfolio ("DRP")
Figure 6-2 shows the projected financial benefits of the DRP based on the range of price
projections used in the analysis for this resource plan. This is based on a portfolio where the
70% goal reached and maintained until 2023, and then additional Wind and Solar are purchased
to reach 100%. Every year enough renewables are purchased to keep up with load growth.
The chart projects the financial performance of Denton's supply portfolio based on a range of
future prices. Positive benefits would result through avoided additional costs if prices rise in
the future. Negative values would result from low price outcomes.
The main takeaway is that the Total System Benefits are completely dependent on the price of
natural gas. This is true because natural gas sets the power price in most markets because it is
the marginal fuel in most markets. This is especially true in ERCOT because of its large fleet of
natural gas units. If gas prices rise, power prices will rise as a result, and over time Denton's
fixed-price renewable resource supply portfolio would result in avoided costs from the higher
power prices. That is the measure for benefits for both Brattle and ERC evaluations. But if gas
prices do not rise, power prices will stay around the current prices and as a result, Denton's
fixed-price renewable resources will not avoid higher market prices and fewer benefits would
result. This is the biggest uncertainty in the entire evaluation. This difference between high
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 68
natural gas prices and lower natural gas prices is a change in total benefits of approximately
$575 million in 2018 dollars.
Figure 6-2
ERC and Bratde Total Benefits of Denbnn Rewneable Portfol'w ($OOOs�
(Siao,aooi So Sloo.aoo Szao.000 S3oo,o0o S�.aoo SSao,aoo Seoo.000 S�oo,oao
6.3 Risks and Opportunities in Selecting Renewable Resources
6.3.1 Resolving the Renewable Status of the Whitetail Supply
Denton can reach its 70% renewable goal with additional renewable resources from the current
RFP submissions. The additional energy to reach the goal ranges from approximately 9%
(140,000 MWh) of its load to 27% (400,000 MWh) of its load. This range depends on whether or
not the Whitetail resource is designated as a renewable resource. More renewable energy is
needed if Whitetail is considered a conventional resource. In terms of energy, a single wind
resource could cover either the additional energy needed (100 MWs of wind is equal to
approximately 400,000 MWhs). Or additional solar could be selected along with a wind
resource (100 MWs of solar is equal to approximately 220,000 MWhs of energy).
The current energy supply portfolio falls far short of a balanced and diversified portfolio
because solar is only 30 MWs. The portfolio is also unbalanced because a large amount of the
renewable supply is a low on-peak West Texas wind profile (Santa Rita). Adding the Bluebell
solar (30 MW) resource will still produce very little summer on-peak production. The DEC is a
heat-rate resource and therefore does not contribute an energy hedge during peak hours (i.e.,
it is a heat rate hedge only until the price of natural gas is fixed).
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 69
This leaves Denton with an on-peak energy supply gap. A minimum of 90 to 120 MWs of solar
would help balance the portfolio against a scenario where natural gas price increases raise the
power price and lower the market heat rate. Therefore, to reach the 70% goal at a minimum,
another 70 MWs of Solar should be considered as an addition to the portfolio. If Whitetail is not
counted, an addition of another 120 MWs of Solar should be considered, with wind
representing the balance of energy needed to reach the 70% level.
6.3.2 Planning Risks
There is a series of known risks that could drive Denton to accelerate reaching the 100% goal,
or decelerate reaching the 100% goal past 2024. These risks are labeled in Figure 6-3. The next
section will discuss some of these risks.
Figure 6-3
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A particular risk in the acquisition plan is that there is a possibility of a federal solar tariff. It is
not clear how the tariff will affect prices or the term of the additional costs, but preliminary
estimates are that it could increase average costs of solar from the current $25/MWh up to
$40/MWh. Under the current price environment $40/MWh is not competitive with wind
resources.
An alternative to avoiding the solar tariff is that Denton could acquire more Coastal wind
resources that feature the characteristic summer peak production profile. This is the closest
substitute for solar among the renewable resources. A second alternative is utility-scale wind
resources with a storage component, now or in the future. Altering the profile of West Texas
wind into a more on-peak production profile will improve hedge effectiveness. A third
alternative is to purchase solar as the tariff prices and supplies readjust to market conditions or
the tariff is no longer an issue. Denton can wait and test the market prices after reaching the
70% level. Waiting on solar would decelerate reaching the 100% goal.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 70
A recent spate of announced coal retirements totaling 4.2 GW of generation capacity from
Vistra Energy (Monticello, Sandow, and Big Brown) may increase power prices during the next
few months. This is likely to have much less impact on the price of wind versus the price of solar
because baseload coal plants count in the market at their full rated capacity amount. Solar
counts at only 77% of its installed capacity in ERCOT and West Texas wind counts only 18% of
its installed capacity. This could accelerate the amount of wind purchased by Denton, especially
Coastal wind as a substitute for solar.
A second accelerator that should be considered is that the PTC has already reduced the subsidy
to wind producers. The supply of wind may be at its maximum now because of the rush to beat
the expiration date of the PTC. Because the supply of available PPAs is highest now, this could
be an inducement to accelerate the acquisition of wind in a buyer's market.
The current natural gas market is reacting to low commodity prices. Natural gas is a byproduct
in many regions. This means that it is a product that does not stand on its own economics for
production, but depends on the crude oil (natural gas is frequently produced in association with
crude oil) or natural gas liquids markets to provide revenue from production. The number of
drilling rig dedicated to drilling for gas has declined to a multi-year low. At the same time,
demand for exports of this low-cost commodity has been driven up to levels never seen before.
Low prices have caused large substitution of the natural gas for coal in the electric power
sector. Coal-based power plants are closing all over the country. In the past, when steady
increases in demand for natural gas have met with a lower number of drilling rigs over a
several-year period, natural gas prices have increased dramatically (e.g., the early 2000s saw
prices double and then triple over a few-year period). This recognition of the risk to natural
gas prices could act as an accelerator to Denton's acquisition plan.
6.4 The Path to 100% Renewable Resources
Denton has adopted the goals of 70% renewable resources ("RE 70") in its power supply
portfolio by the end of 2019, and 100% ("RE 100") by 2035. The evaluation in this resource plan
indicates that the RE 100 goal is achievable much earlier than 2035. There is no financial
penalty or premium to moving from a 70% renewable resource goal to a 100% renewable goal.
This is a decided advantage of ERCOT's energy-only market design. In the ERCOT energy-only
market, PPAs are needed by all consumers without sufficient generation resources if they wish
to lower their supply cost volatility. It is standard practice for consumers to hedge up to 100%
in this market to avoid price risk.
Not only is there no penalty, but because wind and solar PPAs and conventional PPAs are both
composed of the same product (i.e., they are all composed of electric energy priced in $/MWh),
they are substitutable. If a consumer wants to establish a 100% supply hedge, it is easier to
achieve through daily portfolio balancing with a renewables portfolio than with conventional
block purchases. Both renewables and conventional block purchases need to have DAM
purchases and real-time sales to match the variable weather-influenced load profile. The
difference between the two is just a matter of degree as to the ratio of solar and wind PPAs
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 71
acquired and the spot market disposition of the supply. Because solar PPAs cover on-peak
supply exclusively, spot market balancing transactions are less risky and costly than the on-peak
load-following purchases required with a supply portfolio of conventional forward block
purchases. And if wind resources are matched with solar, the combined production profile
offers less risk than that of a convention block, with the resulting production better matching
the profile of load.
����C�a�V A�ca,��irrr� F�,�t4�
Denton has several paths to choose from to reach its RE 100 gal. But the first Denton
Renewable Portfolio (DRP) goal is RE 70 by the end of 2019.
The RE 70 level can be achieved by executing PPAs for low-priced supplies that have been
offered in the current Renewable RFP (Oct 4, 2017). Because this RFP has several viable low-
cost supply options, Denton can easily achieve the 70% level by selecting the lowest cost and
lowest risk supplies for its current supply portfolio. Figure 6-4 shows a possible outcome to
achieve this 70% goal, and eventually the 100% goal by 2024. The chart includes Denton's load,
seen as a gradual increase in the light blue shaded area, additional renewable purchases
labeled "Add. Renewable" and depicted by the red vertical bars, and lines showing the
progression of the proportion of renewable resources and of the amount of supply with fixed
prices.
In the chart, the NextERA Whitetail supply is not counted as a renewable source because it is
not a physical renewable source, but uses Renewable Energy Credits (RECs) to claim renewable
status. An alternative scenario is included later in this discussion that counts the NextERA
Whitetail supply as a renewable energy supply. In either case, additional physical renewable
supplies are required. Depending on the location, price, congestion environment, and the
production profile of the resource, more supply may be added above the additional 47% of load
in energy purchases that are needed to achieve the RE 70% goal by 2019.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 72
Figure 6-4
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Why possibly purchase more than the 47% needed to meet the RE 70 goal? The amount of
additional supply is a function of the uncertainty of renewable production. The amount of wind
production can easily vary by 15% on an annual basis. Figure 6-5 show historic average wind
speed in ERCOT over the last 20 years. The chart shows the 20-year average for both a 24-hour
period and a 7-hour on-peak period, as well as the annual deviation from the 20-year average.
This variability in wind speed will affect the amount of wind production. Some years may be
10% over expected production, others may be 10% under, and if Denton wants to make sure
that it has at least 7D% at a minlmum in every year, it may need to buy additional supplies
above the goal, taking into account the annual production variability.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 73
Figure 6-5
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Another part of the acquisition path depicted in Figure 6-6 is the assumption that Denton will
purchase shorter term (1 to 4-year duration) renewable resources to adjust the RE goal to reach
100% and to constantly maintain that level.
Constantly maintaining a target level can be done with a variety of renewable resources and
demand-side management programs. These should include energy efficiency and adjustments
to load from rooftop solar installations, battery (storage) installations, Demand Resource
programs and any other influences that affect demand. This is a lower-risk strategy because it
is flexible, and allows new technology and commercial programs like household battery storage
and electric vehicle introduction that are uncertain as to the rate of adoption and cost impact.
The magnitude of adoption might be far larger and faster than currently expected. This could be
termed a"Wait and See" strategy.
Besides the new acquisitions that are needed by next year to reach the RE 70 goal, another
larger supply is the replacement of the Whitetail NextERA supply in 2024 because the contract
ends in December of 2023. This acquisition is seen under the "Add. Renewables" category
which shows the annual RE PPAs acquired in each year.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 74
Early Adoption_ Pat_h_
A second path for achieving the RE 100 goal is earlier adoption. This path is predicated on the
fact that the PTC that benefits wind development is ending. The loss of the subsidy will
substantially reduce the number of future wind installations in the state under current
regulations and economic conditions. The current low-cost PPAs for wind may not be available
in the future. Denton would accelerate the wind PPAs acquisition to produce the RE 100% goal
four years earlier, in 2020 rather than in 2024, as shown in Figure 6-6.
Figure 6-6
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This accelerated wind acquisition would result in excess power supply over the next few years
due to the Whitetail non-renewable resource, and Denton would have to manage fixed-cost
risk (the risk of market prices falling because Denton would have more supply than its load for 4
years). If the Early Adoption path is selected, the excess power supply would be approximately
18% for the years 2020 through 2023. The excess supply would end with the Whitetail contract
expiration. This is a potential advantage because it removes the additional demand for a
renewable resource purchase in 2024 if renewable resources are more expensive in the future.
This path corresponds to the potential for a natural gas rate shock in the next few years as the
low rig counts could cause a natural gas price shock while the industry spins up to meet the
large increases in demand that will be driven by growth of liquefied natural gas("LNG") exports
and by the increasing retirements of coal-fired generation units in the grid.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 75
Including the NextERA Whitetail supply in the renewable category will also accelerate the RE
100 goal to 2020. But it also requires replacement of this energy in 2024. This is depicted in
Figure 6-7. The principal advantage of this scenario is that it doesn't produce add9tional fixed-
price supply (the 18% excess supply discussed previously). The principal disadvantage with
including Whitetail in the supply portfolio is that it could cause an audit risk as to the validity of
its renewable status. The REC program does not require load to be tied to actual
contemporaneous renewable production. It can be from any renewable resource or
combination of resources. It can be used in an abstract financial sense. The credits could be
used to represent production in previous years and do not represent a contemporaneous
physical offset. Because these RECs are not tied to renewable costs, there is a great deal of
controversy about their use. This is particularly problematic for a municipal utility that is
exempt from the Renewable Portfolio Standards that enabled this program, and it could
increase the organization's reputation risk.
Figure 6-7
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6.5 Additional Considerations
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The analysis and evaluation for this resource plan assumes that Gibbon's Creek will be
decommissioned by 2018.
An 85% renewable goal may be a natural fit based on Denton's load and the daily and seasonal
production profiles of renewable resources.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 76
Figure 6-8
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For example, consider the month of March. The chart in Figure 6-8 shows a typical disposition
of resources in the month of March at an 85% renewable goal. March is the time of year that
would typically require a lot of excess sales of energy due to seasonally high wind production.
But at 85% renewable (which would leave open 15% of Denton's load), only minimal sales in
some early-morning hours would be required as can be seen by the bars in the chart that
extend below 0. "Solar 90" and "Coastal 75" represent prospective purchases of those
resources at 90 MW and 75 MW respectively. At a 100% renewable goal, there would be much
more excess sales in certain hours. So, an 85% renewable goal may be a more natural fit to
reduce the impact of sales of excess supply.
Potential risk is affected by how Denton chooses to reach its renewable goal. Different
combinations of renewable resources will change where Denton will be long and short in
certain hours and during certain times of year. For example, a greater amount of Coast wind
could be substituted for Solar. This could reduce the potential risk to Denton of a retroactive
Solar tariff.
Figure 6-9
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December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 77
Figure 6-9 shows a daily profile from the Month of March at a 70% renewable goal with the
addition of 75 MW of Coastal wind and 90 MW of Solar. Excess sales are reduced in the early
morning hours, and a greater amount of purchases are necessary in the earlier and later parts
of the day to match load requirements.
Figure 6-10
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Figure 6-10 show the March profile at a 100% renewable goal, reached by adding 200 MW of
Coastal wind and 120 MW of solar. Sales of excess power increase, and would occur in the
early morning hours and during on-peak hours.
Figure 6-11 shows the 12 monthly production profiles at a 100% renewable level reached by
adding 150 MW of Coastal wind and 180 MW of Solar. An alternative is shown in Figure 6-12,
showing the 12 monthly production profiles at a 100% renewable level, reached by adding 200
MW of Coastal and 120 MW of Solar.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 78
Figure 6-11
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200 MW of Coastal and 120 MW of Solar is a different configuration to get to 100% Renewable.
This is a configuration where additional Coastal substitutes for some Solar. This combination
would be more attractive depending on the degree of concern about a potential federal Solar
tariff. It would be possible to substitute even more Coastal wind for Solar.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 79
If it seems less risky to wait to purchase Solar at a later time, to wait for resolution on the Solar
tariff issue, Denton could substitute more Coastal wind for Solar. Coastal wind could be
featured to get Denton up to the near-term renewable goal of 70%, with the quantity
dependent on the decision of how to classify Whitetail, and then wait on a resolution of the
Solar tariff issue, and then purchase more Solar in the second stage of purchases to get up to
100% renewable.
The concern is that Solar could go from prices in the mid-$20 per MWh to the low-$40s per
MWh, and at that level it would no longer be a least-cost supply alternative.
PTC and ITC Reduction and Elimination Schedules
Figure 6-13 shows the reduction and elimination schedules for the federal PTC and ITC. Wind
tax subsidies go away by 2019. The wind PTC is already being reduced. Construction needed to
have started in 2016 to avoid the first reduction of 20%.
The reduction schedules also reinforce the idea that it is less risky to wait on Solar, whereas
earlier action on wind ensures better pricing because of the remaining PTC subsidy.
Figure 6-13
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2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Future
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7.0 Summary of Recommendations
To reach its goal of a power supply that is 100% renewable energy, Denton should purchase
200 MWs of solar, preferably in two locations, and 100 MWs of Coastal type wind. Both of
these types resources should have low congestion risk. Most of the solar proposals are due to
come online by December 31, 2020. Several of the wind proposals will come on line in 2019.
The execution of the resource plan is dependent on actual proposals, and terms and conditions
from the RFP offers.
An optimal location representing a balance of sufficient irradiance, limited cloud cover, and
manageable congestion for would be close to Midland, Texas.
DME needs to hedge both its load with HB North to LZ North CRRs and its resources with
Resource Node to HB North CRRs for the upcoming Santa Rita Wind as well as the Blue Bell
Solar farm.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 80
f�,��r.��i�r� �u��rr�nr��r�
In addition to the recommended amounts, types and locations of renewable resources, Denton
will need to make several decisions that will shape the development of its renewable resource
supply portfolio.
� Count Whitetail as a renewable resource?
o If not, is Denton willing to handle the additional fixed-price risk of the Whitetail
supply in addition to the fixed-price quantity of renewable resources necessary
to meet Denton's goal(s)?
• Will Denton choose to delay solar purchases because of a potential federal solar tariff?
o If so, potential alternatives include:
■ Purchase additional amounts of Coastal wind as a substitute?
� Alter the profile of wind resources with storage?
� Delay solar purchases until the issue is resolved, or solar prices and
supplies adjust to the tariff
� Should Denton accelerate renewable purchases, especially of wind resources, because
of:
o increasing retirements of conventional fossil fuel generation capacity?
o scheduled reduction in the PTC?
o risk of rising natural gas prices?
• Should Denton move forward the date of the 100% renewable goal?
• Should Denton purchase additional renewable supplies above its target levels because
of the annual variance in production amounts?
� Portfolio allocation decisions — there are various allocations between Coastal wind and
Solar to meet Denton's goals (e.g., 180 MW of Solar and 150 MW of Coastal to meet a
100% goal, or 120 MW of Solar and 200 MW of Coastal). What is the preferred
allocation?
Final Version Addendum
Based on feedback from the City of Denton Public Utilities Board, and the Denton City Council,
the following decisions have been made:
• Count Whitetail as a renewable resource? No
• Will Denton choose to delay solar purchases because of a potential federal solar tariff?
No
� Should Denton accelerate renewable purchases? Yes
• Should Denton move forward the date of the 100% renewable goal? Yes
Other decisions will be finalized in the RFP evaluation process, as they will be a function of the
final economic value determined through the evaluation process and final PPA negotiations.
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 81
Appendix A- Hedging 101 & Applications for�Denton
The purpose of commodity hedging is to mitigate the risk of adverse financial exposures
resulting from the commodity-based business operations of the hedging party. Hedging is
typically focus primarily on price risk, but with demand-driven commodities like natural gas and
power, it also focuses on the adverse financial exposure from volume risk.
Before discussing the objectives and mechanics of hedging, it is important to introduce some
concepts and definitions:
Floating price exposure — an exposure to variable market prices resulting from an
obligation to supply a commodity without sufficient resources to do so, or ownership of
commodity resources (or an obligation to take delivery) without known sales revenues.
Floating price exposures involve a volumetric obligation that has a yet-to-be-determined
price.
Fixed price exposure—the opposite of a floating price exposure: an obligation to
purchase or sell a quantity of a commodity for delivery in the future at a known price
today, or a paid inventory of a commodity.
Native exposure (or native physical exposure) — one or more floating price exposures
that are native to the ongoing market operations of the hedging party. An example is an
electric distribution utility that has an obligation to provide energy to its customers but
lacks the fixed-price generation resources to do so. Because it has a lack of generation
resources it must acquire the needed energy supplies in the open market.
It is exposed to price uncertainty during any measurable period in the future when it has
insufficient energy resources while maintaining its obligation to serve its customer base.
Relative to its fixed rate structure (fixed sales revenues), falling power prices in the
future would benefit the utility, whereas rising power prices in the future would hurt
the utility. Yes, utilities often have some degree of control over changing rates, which
can allow adjustments for changing supply prices, and in the long run can substantially
reduce supply cost risk, but the ability to raise rates may be limited for various reasons,
and thus a utility may seek to reduce its exposure, completely or to some degree, to
potentially higher prices.
For illustrative purposes, additional examples of a native exposure include:
• the risk of falling prices for a natural gas producer
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 82
the risk of reduced margins for a petroleum refiner that has exposures to both
rising and falling prices. A refiner is detrimentally exposed to rising crude oil
prices and falling prices for oil products (e.g., gasoline, diesel, jet fuel).
Note — a natural gas fired power plant has a native exposure similar to that of a
petroleum refinery. A gas fired plant is exposed to falling power prices and rising
natural gas prices. This is the native physical exposure of the DEC.
Short position — a short position refers to a native exposure where the hedging party
has an obligation to sell to end users at a fixed price, but lacks sufficient supplyto meet
its sales obligation, and thus is exposed to the floating price risk of potentially rising
prices for supplies it will be obligated to purchase in the future. A short position is a
label for a native exposure based on a shortage of supply.
Denton's native physical exposure is a short position. One part of the DEC's native
physical exposure is a short fuel position.
Long position — a long position is the opposite of a short position. It is a native exposure
where the hedging party has an excess of supply, or has a greater quantity of ownership
compared to its fixed price sales obligations, and is exposed to the floating price risk of
potentially falling prices for inventory that it plans to sell in the future. Natural resource
commodity producers typically have a native long position.
The other part of the DEC's native physical exposure is a long power position (combined
with its native short fuel position).
Opposition hedge — a useful definition of hedging is the following: the establishment of
one or more positions* to reduce financial uncertainty or risk from a floating price
exposure.
*In this context, the definition of a�sr��r�r� is a fixed-price contractual obligation to
make or take physical delivery, or to make or take a financial settlement based on a
commodity price differential. The key to risk reduction is that the hedge position has a
fixed-price that offsets the floating price exposure of the native physical position.
An ideal opposition hedge would be both epual and ��,��:���� of the native exposure
being hedged:
• Equa1 in terms of the quality, quantity and duration of the exposure being
hedged (or the chosen quality, quantity and duration based on the risk
tolerance or risk preference of the hedging party), and
• t��pcasi�°� in terms of market direction:
o a long position to hedge a short native exposure
o a short position to hedge a long native exposure
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 83
A producer hedges its exposure by making fixed-price sales in the future to offset excess
supply. A consumer (like DME) hedges its exposure by making fixed-price purchases in
the future to offset the floating price exposure of a native shortage of supply.
A perfect hedge would result when long positions (or exposures) exactly balance short positions
(or exposures) in terms of quantity, quality and duration. A perfect match would result when
the financial exposure is completely balanced (no net short or long exposure), and no credit risk
exists with any counterparties to any unsettled positions. Of course, no such thing as a perfect
hedge exists.
For Denton to hedge its native short position, it needs to purchase fixed-price energy for
delivery in the future. These energy purchases (e.g., PPAs, forward purchases from the market)
are long positions that hedge Denton's short market exposure. Denton's supply portfolio
management operation is a hedging operation to manage the price risk (and volumetric risk) of
its native short physical position.
Note — it is important to understand that the DEC is an incomplete hedge. The DEC can produce
power at a fixed heat rate, but until a supply of natural gas has been procured �art ��'�x�r� �rri��,
the DECstill results in a floating short exposure to natural gas prices. Only when a fixed price
for natural gas is paired with the fixed heat rate of the DEC will the result equal fixed-price
power.
Hedges frequently come in two parts, or require two separate transactions to make up a
complete opposition hedge: a commodity hedge and a basis hedge. Unless the market pricing
of the hedge position perfectly tracks the price exposure of the native exposure, a basis risk
exists. This leads to another concept and definition:
� Basis — there are two definitions of basis. There is a narrow, textbook, futures market-
oriented definition, and a broader definition for markets where non exchange-traded
instruments are used for hedging (DME's circumstance).
The textbook definition: the basis is the difference between the local cash price of a
commodity and the price of a specific futures contract of the same commodity at any
given point in time. Basis = local cash price —futures price.
A perfect example of this comes from the natural gas market. A primary hedging
instrument in natural gas is the Henry Hub natural gas futures contract based on a
delivery point in Louisiana, and traded on the New York Mercantile Exchange (NYMEX)
division of the Chicago Mercantile Exchange. Yet the vast majority of hedgers using
NYMEX natural gas futures are exposed to a local cash price based on a pipeline pricing
December 5, 2017 Renewable Resource Plan for the City of Denton from Enterprise Risk Consulting, LLC 84
point other than the Henry Hub. For example, an electric utility with natural-gas fired
generation in northern California will pay a local cash price for natural gas typically
based on the PG&E city gate natural gas price index. If it uses Henry Hub natural gas
futures contracts as a hedging instrument, it is exposed to the basis of PG&E city gate
prices versus Henry Hub prices (geographic price differential).
The correlation between PG&E city gate prices and Henry Hub prices is positive, but not
that highly positive, and this results in a substantial price and value tracking error. The
financial payoff of the futures contract hedge will not match the price change over the
life of the hedge of a physical exposure based on the PG&E city gate price index,
resulting in a suboptimal and imperfect (aka "dirty") hedge.
If a hedger can tolerate the financial uncertainty (risk) of a price index mismatch (e.g.,
PG&E city gate index vs. Henry Hub index), it may choose not to hedge the basis. But if
the hedger decides that it needs to manage the basis risk, it may choose to execute a
separate, second transaction to hedge just the basis. For example, a gas-fired electric
utility in northern California might hedge its risk of rising natural gas prices by a)
purchasing natural gas futures contracts (commodity hedge) and b) by purchasing a
basis swap contract that will financially settle based on the difference between the
PG&E city gate index and the Henry Hub index (basis hedge). This two-component
hedge is commonplace in the natural gas industry.
Thus, a complete opposition hedge requires hedging both the commodity risk and the
basis risk.
Fortunately, ERCOT offers a separate instrument for hedging basis risk — Congestion
Revenue Rights (CRRs), with two types that pay off like swaps (CRR obligations) or
options (CRR options). CRRs will be addressed further in the next section of this
document.
The broader and more useful definition of basis is that it is the difference between the
local cash price of a commodity and the price of the hedging instrument of the same
commodity at any given point in time. In Denton's terms, it would be the difference
between the local cash price of energy that Denton needs to meet its load requirements
versus the price of its hedging instruments (e.g., PPAs and forward energy purchases).
�r � s � . * " � N � ,
To further explore this topic, it is important to recall how ERCOT prices energy. Consumers
purchase energy at load zones and power plants sell energy at resource nodes. Generally, the
prices of resource nodes do not match those of load zones because of congestion in the
transmission system. Energy purchased from ERCOT to meet Denton's obligation to meet its
customer load requirements is priced at Denton's load zone (its "local cash price" in the
definition of basis) whereas energy produced from Denton's generation resources (e.g., PPAs) is
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priced at generation resource nodes. This means that in addition to Denton's native short
position vis a vis electric energy, it also has a basis risk exposure.
As previously mentioned, ERCOT operates a viable market for hedging basis risk: CRRs. CRRs
come in two types: obligations and options. Obligations are like swaps — they have a
symmetrical pay off that can be positive or negative. On the other hand, options have an
asymmetrical payoff profile — they pay off positively for the option holder, but the option
holder is not exposed to a negative payoff. NOIEs can link CRRs to an option to hedge DAM to
RT congestion.
ERCOT congestion (basis) risk can be hedged for years forward by consistent participation in the
CRR market. It is important to realize that not hedging basis (congestion) risk is implicit
speculation on the basis. It is a conservative hedging and risk management practice to perfect
hedges as much as possible, and this includes hedging basis risk
Note — although it is recommended to pursue a conservative approach and hedge the basis
(congestion risk), not hedging the basis is fine, IF it is a conscious decision by senior
management and is explicitly acknowledged as an unhedged risk in Denton's energy risk
management policy.
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