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 2012, 2011, 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002, 2001 and 2000. Learn more about the TRI program and how it relates to electric utilities.
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.
Companywide, Dominion's total TRI air emissions have decreased from approximately 17 million pounds in 2000 to approximately 3.6 million pounds in 2012. 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. A scrubber began operation at Chesterfield Unit 6 in 2008 which contributed to the air release reduction. The addition of scrubbers at Brayton Point Units 1 and 2 and activated carbon injection on Units 1, 2 and 3 at Brayton Point have resulted in further reductions.
Further air emission reductions are occurring from an additional SO2 scrubber at Chesterfield Power Station which became operational at the end of 2011. Air emissions reductions also will occur in 2013 with the completion of a third scrubber at Brayton Point Power Station. TRI releases to land have, primarily in our onsite disposal areas, decreased from approximately 8 million pounds in 2000 to approximately 5.5 million pounds in 2012.
TRI releases to water are a very small portion of Dominion's total TRI releases.
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, the repowering of two coal-fired boilers to cleaner-burning natural gas at the Possum Point Power Station, the addition of a SO2 scrubber at Chesterfield Unit 6, and the addition of two SO2 scrubbers and activated carbon injection on three units at Brayton Point.
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 began occurring when an additional SO2 scrubber became operational at the end of 2011 at the Chesterfield Power Station. In addition, when conversion of three stations from coal to biomass is completed, further reductions will be realized.
It is anticipated that mercury emissions to the atmosphere will decrease by approximately 34 percent by 2015 (as compared to 2004 air emissions).