With the global transition to clean energy in full swing,
traditional renewable energy sources such as solar and wind have,
unsurprisingly, been hogging the limelight. Unfortunately, one
powerful renewable energy source has been conspicuously missing in
the conversation: Geothermal energy.
Despite its many obvious benefits, geothermal energy--which taps the
heat within the earth’s crust--is criminally underutilized in the
United States. In 2019, the U.S. generated ~18,300 GWh from
geothermal sources. While that appears impressive at first glance,
here’s the kicker: that figure works out to just 0.4% of U.S. power
generation.
The figures are not much better for Europe, with just 1.5GW of the
continent’s 209 GW electricity capacity being geothermal. Only about
800 geothermal wells are drilled globally each year compared to more
than 100K oil wells.
Geothermal energy has two primary applications: electricity
generation and heating/cooling.
Geothermal energy can be found almost anywhere: other than
seismically active hotspots, there is a steady supply of milder
heat--useful for direct heating purposes--at depths of anywhere from
10 to a few hundred feet below the surface. This heat can be found
in virtually any location on Earth since it has its origins from
when the planet formed and accreted, frictional heating caused by
denser core material sinking to the center of the planet as well as
heat from the decay of radioactive elements.
Indeed, just 10,000 meters (about 33,000 feet) of the Earth's
surface contains 50,000 times more energy than all the oil and
natural gas resources in the world. Further, unlike solar and wind
which are intermittent energy sources, geothermal is highly reliable
with a high capacity factor of 74.3% vs. 24.9% for solar and 35.4%
for wind.
Another key benefit: geothermal is much cleaner than any fossil fuel
out there. Whereas geothermal power plants are frequently associated
with sulfur dioxide and silica emissions as well as traces of toxic
heavy metals including arsenic, mercury, and boron, the emissions
profile of geothermal energy is nowhere near as bad as those of
fossil fuels.
The U.S. Energy Information Administration (EIA) says geothermal
power plants emit about 99% less carbon dioxide and 97% less acid
rain-causing sulfur compounds than fossil fuel power plants of
similar size. Further, geothermal power plants are frequently
equipped with scrubbers to remove the hydrogen sulfide naturally
found in geothermal reservoirs. It’s, therefore, hardly surprising
that a country like Iceland--which derives ~two-thirds of its
primary energy from geothermal sources--has only one-third the
greenhouse gas emission per capita as the United States.
But the same technology that powered the U.S. shale boom might help
unlock the full potential of U.S. and Europe’s geothermal resources.
Source: Center for Sustainable Systems