I understand that enhanced geothermal systems (EGS) projects are still in experimental stages, and it may take decades before we can use it to produce energy. Is this correct? — Devino R., Houston, TX
While reaching the full potential of EGS may take a decade or more to realize, there are many aspects of EGS that are already being applied and that will provide expanded geothermal energy in the years immediately ahead.
Let’s set down some basics. Geothermal energy production requires heat, water and fractured rock. Since heat is available anywhere under the surface of the Earth, water and fractured rock are what geothermal explorers look for in a potential “natural” geothermal site.
EGS involves developing tools and techniques that will allow geothermal production by artificially creating permeability in hot rock and introducing water (or another working fluid) to extract the heat. The widely publicized MIT report on EGS, The Future of Geothermal Energy, estimates that for EGS power plants there could be “performance verification at a commercial scale within a 10-15-year period nationwide.” But that doesn’t mean we will have to wait decades to see results from an investment in EGS research and technology development.
As the MIT study points out, “in a manner similar to the technologies developed for oil and gas and mineral extraction, the investments made in research to develop extractive technology for EGS would follow a natural learning curve that lowers development costs and increases reserves along a continuum of geothermal resource grades.”
The processes of adding water or fracturing rock to improve geothermal production are currently applied in many geothermal operations. In California at The Geysers field — the oldest geothermal field in the United States and the largest geothermal venture in the world — operators have expanded the capacity of wells by injecting millions of gallons of reclaimed wastewater into the geothermal reservoir. Some experts call the Geysers wastewater project the first large-scale EGS project. Fracturing wells to increase their productivity, which is a common practice in oil and gas fields, is becoming more common in geothermal reservoirs albeit at a smaller scale.
EGS production ultimately would involve the extensive resource base of hot rocks that do not have any other significant geothermal characteristics and production will be made possible almost entirely by engineering techniques. This, as well, is not necessarily decades away. There are several EGS projects that are already, or will soon, produce power:
The Soultz project, in France, a 1.5-megawatt (MW) EGS plant already in operation
The Landau project, in Germany, a 2.5-MW operational plant
Paralana, in Australia, a 7-30-MW plant in drilling stages
Cooper Basin, in Australia, a 1-MW showcase plant will be operational in 2008 and a 250 – 500-MW plant in drilling stages, expected to have the first 50 MW EGS plant operating as early as 2011-2012
Desert Peak, in the U.S. (Nevada), in planning stages, the expansion of an existing natural geothermal field
These early projects show the potential for EGS to contribute to national energy needs in years instead of decades.
So, to return to your question, the assumption that deriving power from EGS technology is decades away is simply incorrect. Developing EGS technologies will provide expanded power production both in the near-term and even more in the long run. It may take time to expand commercial use of EGS technologies to the point where they are making a significant contribution to national energy needs, but assuming there is a sustained and substantial commitment to supporting the development of EGS technologies — which is still an open question — ramping up production very quickly should be a feasible option to help meet our need for clean energy.