In the last few years, the growth in the geothermal power industry in the U.S. has been slow but consistent. Geothermal Energy Association’s recent press release reveals fresh numbers showing a net gain of 91 MW in 2011, making the new total capacity 3187 MW – significantly more than any other country in the world.
Note that this article is strictly about electricity generation from geothermal energy. In other words, this article is neither about geothermal heat pumps nor any other direct heating applications of geothermal energy.
While the net geothermal power capacity in the U.S. is high, the relative output compared to the country’s power consumption isn’t. Geothermal electricity generation only accounts for about 0.3% of the nations net production. This is nothing compared to countries that have rich geothermal resources (that can be exploited in a cost-competitive manner) such as Iceland, the Philippines and El Salvador, where almost 30% of the net production comes from geothermal energy.
Technological breakthroughs increases the geothermal potential dramatically
The technology within the geothermal industry has been improving steadily over the last decades. By developing binary cycle power plants we make use of geothermal resources that otherwise wouldn’t be financially viable. This power plant type is not reliant on high-temperatures as its precursors the flash- and dry-steam power plants are. By using a working/carrier fluid with a lower boiling temperature than water, we can provide steam to the turbines with as low water-temperatures from the geothermal wells as 57°C (135°F). In comparison, dry-steam and flash-steam power plants requires water temperatures of at least 150°C (300°F) and 182°C (360°F).
The U.S., and a handful of other countries, is currently looking into enhanced geothermal systems (EGS) as a way to expand our geothermal potential. By drilling deep into geothermal reservoirs that have too low permeability to be exploited by conventional methods (hot dry rocks), then using high-pressure water to fracture the rock, we can create thousands of tiny pathways where water can flow. By sending water down to the reservoir, it gains thermal energy from its surroundings, which we can later use to generate electricity in our steam turbines above the surface (exactly as we would do in a geothermal reservoir where high-permeability rock and naturally occurring water is present).
Binary cycle power plants and enhanced geothermal systems both contribute to a dramatic increase in expanding our viable geothermal resources. It has been estimated that the true annual geothermal potential is somewhere around 14 million EJ (exajoules) in the U.S. alone – 140 000 times the total power consumption of the country! (Massachusetts Institute of Technology, 2006)
The way I see it, there is one main reason why the U.S. is struggling to make more use of their geothermal resources:
Inconsistent Government policies
Geothermal power, as with other renewables such as wind and solar power, has to be backed by government policies to ensure that the resources can be exploited in a cost-competitive manner. Without it, geothermal power stand no chance against convectional energy sources such as coal and fossil fuels, which have received financial support in the past and still is receiving to some extent.
Karl Gawell, Executive Director of GEA, stated the following about the importance of incentives in the recent press release:
“The geothermal industry looks to our policy leaders to provide a stable environment to foster growth that could lead the U.S. toward greater energy independence.”
Gawell continued: “As Washington debates whether or not to extend renewable energy tax incentives, the industry struggles to continue steady growth. Stable tax credit policies would further enhance this development. “
Eight states are currently generation electricity with geothermal energy and another seven are currently spread out in the different stages of developing geothermal power.
“As the economy strengthens, our industry is expected to bring even more geothermal capacity online in the coming years,” Gawell said. “In 2012, another 100 MW of capacity is expected to come online representing nearly one billion dollars of investment in the clean energy economy.”
Visit Mathias\’s site EnergyInformative.org where you can learn more about geothermal energy as well as wind and solar power.