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"Given the current scientific understanding
of the environmental fate and transport of this element, it is
not possible to quantify with precision how much of the methylmercury
in fish consumed by the U.S. population is contributed by U.S.
emissions relative to other sources of mercury." |
The Environmental Protection Agency reports that U.S. electric utilities released 48 tons of mercury in 1999, the latest year for which data are available. This comprises about 40 percent of manmade mercury emissions in the U.S., 10 percent of total North American emissions, and just 1 percent of total global mercury emissions. Electric utilities are taking steps to reduce mercury emissions from power plants as part of ongoing pollution prevention programs. In fact, existing control technologies for sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter reduce power plant mercury emissions by roughly 40 percent. Mercury emissions from power plants will continue to decline due
to current and future regulatory requirements for controlling SO2
and NOx, in addition to EPA's first-ever mercury regulations for
the power sector.
What forms of mercury are emitted from power plants? What are electric utilities doing to curb their mercury
emissions? What forms of mercury are emitted from power plants?Coal is an abundant domestic resource and is among the most affordable energy options available. Coal-based electric generation is a crucial part of electric utilities' success in providing affordable and reliable electricity. Currently, coal accounts for 50 percent of our nation's electricity. During coal combustion, two forms of mercury are released from a power plant: oxidized (or ionic) mercury, which is water-soluble, and elemental mercury, which is not very water-soluble. Oxidized mercury can be washed into local waterbodies by rainfall. Of the total mercury formed, the amount of elemental mercury varies from 10 percent to 90 percent. Almost all of the elemental mercury and most of the oxidized mercury are carried away by wind and enter the global mercury cycle. After power plants release mercury, much of it becomes part of a global cycle. Current research indicates that, on average, for most of the U.S., over 60 percent of the mercury measured at monitoring stations, and thus deposited on land or water, originates outside the country.1
What are electric utilities doing to curb their mercury emissions?Electric utilities are taking steps to reduce mercury emissions from power plants as a component of ongoing pollution prevention programs. Electric utilities are actively helping the Department of Energy (DOE) test the effectiveness of emerging, mercury-specific control technologies. DOE's goal is to develop more effective options that will cut mercury emissions 50 percent to 70 percent by 2005 and 90 percent by 2010 at one-quarter to one-half of current cost estimates. Power sector emissions will be further reduced, as new controls are deployed to meet current ozone and acid rain program requirements, and through EPA's recent mercury rulemaking, which mandates significant reductions of mercury. Existing control technologies for SO2, NOx, and particulate matter reduce power plant mercury emissions by roughly 40 percent. EPA, DOE, and other experts agree that the implementation of further controls for reducing SO2 and NOx, as required by current regulations, will result in significant additional reductions in mercury emissions. Mercury emissions will continue to decline due to current
regulatory requirements for controlling SO2 and NOx,
in addition to EPA's mercury regulations for the power sector. The
additional controls that many large coal-based power plants will
install will remove the oxidized form of mercury, the form most
likely to deposit locally.
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Trace amounts of 
