In 2002 about 40% of U.S.
carbon dioxide emissions stem from the burning of fossil fuels for the
purpose of electricity generation. Coal accounts for 93 percent of
the
emissions from the electric utility industry. US
Emissions Inventory 2004 Executive Summary p. 10
Coal emits around 1.7
times as much carbon per unit of energy when
burned as
does natural gas and 1.25 times as much as oil. Natural gas gives off
50% of
the carbon dioxide, the principal greenhouse gas, released by
coal and
25% less carbon dioxide than oil, for the same amount of energy
produced. Coal
contains about 80 percent more carbon per unit of energy than gas does,
and oil
contains about 40 percent more. For the typical U.S. household, a
metric ton of
carbon equals about 10,000 miles of driving at 25 miles per gallon of
gasoline
or about one year of home heating using a natural gas-fired furnace or
about
four months of electricity from coal-fired generation.
