The Toxic Release Inventory (TRI) is an EPA regulatory program
that requires companies to report on their environmental releases of any of
about 650 chemicals on a specified list. About 25,000 facilities in the United
States report under this program. Dominion's fossil-fueled power stations
release some of these substances during the generation of electricity. A TRI
release summary for each station can be viewed for 2006, 2005, 2004,
2003,
2002,
2001 and
2000.
Learn more about the TRI
program and how it relates to electric utilities.
Where the Releases Come From
By-Products: Several chemical compounds
are created as by-products during the combustion of fossil fuels — namely,
hydrochloric acid, hydrogen fluoride, sulfuric acid and low levels of dioxin.
Trace Elements: The fossil fuels combusted
to produce energy contain trace amounts of other compounds. As a result of
combustion, some of these other compounds can be released to the environment.
Metal compound emissions (including compounds of arsenic, barium, beryllium,
chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium, vanadium,
and zinc) are the result of trace elements in the fuel. Emissions of polycyclic
aromatic compounds (PACs) and benzo(g,h,i)perylene are primarily the result
of trace materials found in #6 fuel oil.
Purchased Chemicals: In some instances,
chemicals are purchased for use at our stations and can potentially be released
in some way during use of the product. Chlorine is used for disinfection of
water at some stations. Some of our processes require the use of hydrazine
to maintain an oxygen-free environment. Ammonia is used in air pollution control
equipment to reduce nitrogen oxide emissions. And, ethylene glycol is used
as a heat transfer agent and to provide freeze protection at some stations.
Overview of Total Emissions
Companywide, Dominion’s total TRI air emissions have
decreased from approximately 17 million pounds in 2000 to approximately 13.9
million pounds in 2006. The graph reflects releases for facilities owned by
Dominion by calendar year.
The overall downward trend reflects the addition
of air pollution controls at Dominion's power stations. The increase from 2004
to 2005 reflects the addition of three stations in 2005: Brayton Point, Manchester
Street and Salem Harbor.
The air releases dropped from 16.9 million
pounds in 2001 to 13.6 million pounds in 2002 as a result of the scrubbers
at the Mt. Storm Power Station. The conversion of Possum Point units #3 and
#4 from coal to gas firing also contributed to decreased air releases in 2003.
Further air emission reductions
will occur with the installation of controls to be installed to meet the
requirements of the Clean Air Interstate Rule and state regulations. By
2010, it is anticipated that sulfuric acid emissions will have decreased
by approximately 15 percent, that hydrochloric acid emissions will have
decreased by approximately 69 percent, and that hydrogen fluoride emissions
will have decreased by approximately 56 percent (as compared to 2004 air
emissions).
TRI releases to land have, primarily in our onsite disposal
areas, increased slightly from approximately 8 million pounds in 2000 to approximately
8.4 million pounds in 2006. This increase is due to the acquisition of new
generating stations.
TRI releases to water, which are a
very small portion of Dominion's total TRI releases, have increased slightly
due to the acquisition of new generating stations.
Total Mercury Releases(reported under TRI)
Mercury is often found in trace amounts in fossil
fuels. When the fossil fuels are combusted, the high combustion temperatures
and the volatility of mercury and mercury compounds results in mercury being
emitted in the combustion gas exhaust stream. Mercury and mercury compounds
can also be found in the ash.
Dominion has reduced mercury air emissions through the installation
of two additional SO2 scrubbers at the Mt. Storm Power Station and the repowering
of two coal-fired boilers to cleaner-burning natural gas at the Possum Point
Power Station.
Additional mercury air emission reductions are being achieved
across the Dominion coal-fired generation fleet through existing particulate
matter controls and advanced NOx controls.
Further mercury air emission
reductions will occur with the installation of SO2 scrubbers at the Chesterfield
Power Station.
Additional controls will be implemented to meet the
requirements of state mercury regulations, Clean Air Interstate Rule and
the Clean Air Mercury Rule across Dominion’s fleet of coal fired
generating stations.
It is anticipated that mercury emissions to the atmosphere
will decrease by approximately 29 percent by 2010 and approximately 34
percent by 2015 (as compared to 2004 air emissions).
Releases are shown for facilities in the
year when owned by Dominion. Despite the acquisition of several facilities,
air releases of mercury have declined. Disposal of ash containing mercury
occurs primarily in onsite disposal areas.
