Barrons AP Environmental Science

year old) organic matter under high temperature and pressure. Sulfur, from the
decomposition of hydrogen sulfide (H 2 S) by anaerobic bacteria, became trapped

in coal. There are three types of coal:

■ LIGNITE   has the lowest  heat    content.

■ BITUMINOUS    has high    sulfur  content and constitutes 50% of  the U.S.    coal

reserve.

■ ANTHRACITE    has high    heat    content and low sulfur  content.    It  makes   up  2%

of  the U.S.    coal    reserves.

Coal supplies 25% of the world’s energy, with China and the United States
consuming the most. In the United States, 87% of the coal is used for power
plants to produce electricity. The Clean Air Act requires up to a 90% reduction
in the release of sulfur-containing gases.
Coal is the world’s single largest source of fuel used to produce electricity.
The United States has the largest proven recoverable coal reserves in the world,
whereas China is the world’s largest producer of coal. Global coal reserves are
estimated to last about 300 years at current levels of extraction, with continuing
issues of CO 2 emissions and global warming.

Figure  8.4 World   recoverable coal    resources   by  region

The following technologies can be used to remove pollutants from the
burning of coal:

■ BAGHOUSE  FILTERS:    fabric  filters that    can be  used    to  reduce  particulates.