Geo
(Earth) thermal
(heat) energy is an enormous (巨大的),
underused (未充分
利用)
heat and power resource that is
clean
(emits little or no greenhouse gases),
reliable
(average system availability (有效性)
of 95%), and
homegrown
(making
us less dependent on foreign oil).
Geothermal resources range (分布，排列)
from shallow ground to hot water and
rock several miles below Earth's surface,
and even farther down to the extremely
high temperatures of molten rock called
magma.
Earth's energy can be converted (转换)
into heat and electricity. The three
technology categories (种类)
are geothermal heat pumps, direct-use applications
(应用),
and power plants.
