Geothermal has long been touted as the only stable form of renewable energy because it produces constant 24-hour energy from hot rocks deep underneath the ground.
Like the energy it produces, the geothermal industry is proving to be strong and steady as well. According to a recent Geothermal Energy Association (GEA) report, the industry grew steadily in 2011, adding approximately 91 megawatts (MW) of capacity despite the prospect of a production tax credit expiring at the end of 2013.
Geothermal power is perhaps one of the least well known of all the renewables, but it is a surprisingly massive potential source of green energy.
Rocks can store an incredible amount of heat and deep beneath the surface of the Earth they can store the core heat from the center of our planet. (See Do the Math's essay for a complete exploration of how geothermal works.)
Like oil rigs, geothermal plants must be located on specific sites of underground rock that have stored heat and are formed in a way that they can be drilled. Careless drilling can both lead to heat escape and earthquakes.
In a recent interview with AOL Energy, GEA Executive Director Karl Gawell said that preliminary geological studies in the western United States have found as much as 75,000 MW of undiscovered geothermal potential energy under the earth. There have been about 10,000-15,000 MW worth of identified systems in the region. Across the country, he believes there is much much more potential, especially if the U.S. Department of Energy invests more money into research and development and helps the industry unlock even more reservoirs.
There are currently geothermal installations in eight states: Alaska, California, Hawaii, Idaho, Nevada, Oregon, Utah and Wyoming. Arizona, Colorado, Louisiana, New Mexico, North Dakota, Texas and Washingto have geothermal rocks that are currently being tapped. But as always, California is leading the pack with 2,615 MW of geothermal power already connected to the grid and another 2,000 MW under construction. Nevada is in second place with 59 geothermal projects under construction.
"We're often the much smaller voice, particularly in Washington," Executive Director of the Gawell told AOL Energy in December. He said the industry has been particularly hurt by the short-cycle start-stop nature of energy policy that gives tax credits and cash grants for only a few years at a time.
Geothermal plants can take as long as eight years to construct and developers need stable, long-term policy that they can rely on throughout that period.
But the industry has shown no sign of slowing. Energy companies from around the world are rushing to develop the discovered underground rock sources. Energy Source finished its 49.9 MW Hudson Ranch I project in Imperial Valley, Calif. this year, Israel-based Ormat Technologies finished 26 MW worth of projects over the past year, Terra-Gen completed a 1.9 MW expansion project in Nevada, and U.S. Geothermal expanded its San Emidio plant, adding 12.75 MW of power.
You can download the full GEA report here.