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Short Tons of Mercury Emitted

FIGURE 4-20. Annual mercury emissions in the United States. (From DOE, Quicksilver: Don't Play With It, FETC Focus, Issue 2, March 1999, p 25.)

Based on this, U.S. sources are estimated to have contributed about 3% of the 5500 tons in 1995. Mercury emissions from coal-fired boilers are estimated to be 48 short tons per year.

In a report released by the United Nations Environment Program (UNEP) in February 2003, coal-fired power plants were identified as the largest single anthropogenic source of mercury air emissions [64]. UNEP reported that power plants in Asia contribute the most mercury—some 860 metric tons (note that 1 metric ton = 1.1023 short tons) per year, more than a third of the 2200 metric tons of annual emissions reported coming from major anthropogenic sources. In all, 1470 metric tons of mercury were emitted in 1995 by coal-fired power plants. Other major sources of mercury include metal production (200 metric tons), cement production (130 metric tons), waste disposal (110 metric tons), and small-scale gold mining (300 metric tons).

Carbon Dioxide (CO2)

Carbon dioxide emissions from energy use are shown in Figure 4-21, which provides CO2 emissions by sector and fuel for 1990 and 2001 and projections up to 2025 [65]. Petroleum products are the leading source of CO2 emissions from energy use. In 2025, petroleum is projected to account for 971 million metric tons carbon equivalent, a 43% share of the projected total. Coal is the second leading source of CO2 emissions and is projected to produce 73 million metric tons carbon equivalent in 2025, or 34% of the total.

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