Environmental Engineering Reference
In-Depth Information
get a stream of profi table gas back in return. It is another attempt to
turn the ugly duckling of coal into the relatively white swan of natural
gas, an energy alchemist's dream. But the realities of mining-by-microbe
are no doubt a long way off, if ever, and coal pollution needs to be
stopped as quickly as possible.
Natural Gas Hydrates
Perhaps the most exciting natural gas reserve on the production horizon
are natural gas hydrates, deposits of methane trapped in ice-like crystals
that are abundant both on land in Arctic permafrost regions at depths
of a few tens of feet and at depths of 1,600 to 2,000 feet below the
ocean fl oor. These methane hydrate accumulations look like normal ice
but burn if touched by a fl ame. U.S. deposits are believed to contain
about 150 times as much natural gas as known conventional gas reserves
and about 900 times our current annual natural gas consumption.
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There is no commercial production yet, but there probably will be in
ten to fi fteen years.
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About one-quarter of the world's hydrates are located within the
borders of the United States, in places such as the North Slope of Alaska,
the Gulf of Mexico, and off the coast of South Carolina.
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The produc-
tion of gas hydrates becomes economical when natural gas is priced at
$4.00 to $6.00 per thousand cubic feet or when oil prices are at least
$54.00 a barrel. According to the Department of Energy, if only 1
percent of the methane stored in the world's hydrates could be recovered,
the world would be awash in natural gas.
Coal: The Worst of the Worst
Christmas tradition threatens a lump of coal in the stocking for those
who were naughty. This could easily be done in the United States, where
28.6 percent of the world's supply of coal is located (table 6.7 and fi gure
6.6). We have about 250 billion tons of it, the equivalent of 800 billion
barrels of oil, more than three times the oil reserves in Saudi Arabia.
Coal supplies 22 percent of the energy needs of the United States.
Most coal is mined in Wyoming (38.4 percent), West Virginia (13.1
percent), and Kentucky (10.4 percent). We mined only 1.35 billion tons
of our available 250 billion in 2009, so our reserves of coal are adequate
for perhaps 150 years, depending on future production requirements.
Coal supplies 23 percent of America's energy and 45 percent of its elec-
tric power (down from 57 percent in 1988) from more than 600 power
