2018-101 DEC Emissions OverviewDate: August 10, 2018 Report No. 2018-101
INFORMAL STAFF REPORT
TO MAYOR AND CITY COUNCIL
SUBJECT:
The purpose of this report is to provide the City Council with additional information regarding
the estimated annual emissions of the Denton Energy Center (DEC) as well as background
information on the public health basis of the Texas Commission of Environmental Quality’s
(TCEQ) Standard Air Permit process.
BACKGROUND:
During the June 26, 2018 Council meeting, there were questions asked regarding the DEC’s
annual maximum runtime and the public health basis for the TCEQ’s Standard Air Permit
allowable emissions. Additionally, a request was made for information about the DEC’s
Nitrogen Oxides (NOx), Volatile Organic Compounds (VOC) and Carbon Monoxide (CO)
emissions in relation to the yearly emissions estimated for the Dallas - Fort Worth (DFW) 10
county non-attainment area. This report provides a detailed explanation of the factors that dictate
the DEC’s runtime, an explanation of the TCEQ’s implementation of the Clean Air Act. A table
summarizing and DEC’s emission output to the yearly DFW emissions total is included in this
report.
DISCUSSION:
Congress created the EPA and passed the Clean Air Act (CAA) in 1970. The fundamental goal
of the CAA was to improve human health and the environment by reducing air pollutions. The
CAA required the EPA to set National Ambient Air Quality Standards (40 CFR part 50) for
pollutants considered harmful to public health and the environment. The EPA has granted
authority to the TCEQ to carry out the requirements of the CAA in Texas.
The DEC operates under a Standard Air Permit that was approved and issued by the TCEQ. The
permit lists 7 pollutants along with the maximum authorized emission tonnage that can be emited
per year.
The table below is an excerpt from the permit:
Emission Point
No. Source Name Pollutant
Authorized
Emissions
lbs/hr TPY*
EP-1 - EP-12
Site Wide
Annual
Emissions
Volital Organic Compounds (VOC) - 48.6
Nitrous Oxides (NOx) - 33.8
Cabon Monoxide (CO) - 96.5
Paticulate Matter less than 10
microns (PM10) - 70
Paticulate Matter less than 2.5
microns (PM2.5) - 70
Sulfur Dioxide (SO2) - 1.75
Ammonia Slip (NH3) - 60.9
*TPY stands for tons per year
Date: August 10, 2018 Report No. 2018-101
Permit compliance requires the DEC to generate less than the allowable emissions tonnage
shown above. Based on current ERCOT market conditions, the upper operational window of the
DEC is approximately 2800 hours per year. This would generate approximately 78% of the
allowable tonnage of NOx. The other 6 pollutants would all be under 28% of the allowable
TCEQ permit approved tonnages. If ERCOT market conditions changed, the DEC could operate
upwards of 5000 hours per year and fully maintain compliance with the TCEQ Air Permit values
for all 7 noted quantities (estimate based on 275 total plant starts per year).
TCEQ conducted health impact studies, air quality analysis, and dispersion modeling prior to
making Standard Air Permits available for electric generating units, such as the DEC. In May
2007, the TCEQ published the ‘Amended Air Quality Standard Permit for Electric Generating
Units.’ This document states “Additionally, state and federal permits for combustion units at
power plants ranging from 50 to 2000 MW have been reviewed and modeling has shown that
even much larger units meet all National Ambient Air Quality Standards (NAAQS) and state
standards.” In summary, the TCEQ went through a protectiveness review for the DEC’s standard
air permit and determined that the National Ambient Air Quality Standards would be maintained
with the issuance of the permit.
To meet the request for DEC’s emission output in comparison to DFW estimated emissions, staff
performed a simple percentage calculation comparing the Denton Energy Center (DEC)
emissions in TPY as estimated by an emissions model (number of start/stops and runtime) for the
DEC, to the emissions in the DFW 10 county non-attainment area. The information is
summarized in the following table.
DFW estimated TPY* DEC TPY** % DEC to
DFW
NOx 108,306 26 0.024
VOC 152,840 13 0.009
CO 635,665 26 0.004
*Estimated 2017 10 county Dallas-Fort Worth Areas Summary of Anthropogenic Emissions – Presented by Chris Kite, Texas
Commission on Environmental Quality, Air Quality Division, at the NCTCOG November 6, 2015
** Estimated DEC emissions based on 2800 hours of DEC plant operation, 180 cold starts, 25 warm start, and 50 hot starts.
Black and Veatch presented lower quantites during June 26, 2018 City Council presentation due to fewer cold starts.
Date: August 10, 2018 Report No. 2018-101
Please do not hesitate to contact me if you have any further questions about the operation and
associated emissions of the DEC or the approved State of Texas TCEQ permit.
STAFF CONTACT:
George F. Morrow, DME General Manager
(940) 349-8487
George.Morrow@cityofdenton.com