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Enhanced geothermal systems differ from traditional systems in one major way: They don't require an existing underground reservoir of steam or water. Unlike traditional plants, which are relegated to continental plate boundaries and other areas of naturally occurring geothermal activity, enhanced systems can work in all fifty states.
First, developers drill into areas of hot, dry rock located more than a mile beneath the surface. They inject cold water under low pressure to expand existing fractures in the rock, then drill a second well at the other end of the system. Water is pumped through the injection well into the new fractures, where the hot rock converts it to steam. It's then extracted through the production well, and finally fed into a power plant. In many cases, the same water can be reinjected after cooling — dramatically reducing water use and eliminating the sort of issues faced at The Geysers.
As with hydraulic fracturing in the natural gas industry, the EGS fracturing process poses a risk of inducing small earthquakes. However, seismic monitoring by the Lawrence Berkeley National Laboratory at various drill sites has shown the risk to be negligible, largely because water is injected at low pressure — it essentially seeps into the earth under gravity, relying on the temperature differential to create cracks. EGS fracturing also differs from natural gas fracking in that it uses clean water, free of chemicals that could contaminate drinking supplies.
The Obama administration appears convinced of geothermal's promise. Along with $341 million in stimulus funds for the development of geothermal technologies, the Energy Department allots a separate annual amount for geothermal energy, just as it does for solar, wind, biomass, and hydrogen. The geothermal program has received about $37 million in each of the last two years, but that figure is expected to nearly double to $65 million in 2013. The Department of Energy's solar program, by comparison — which admittedly dwarfed geothermal at $289 million this year — may grow by only 7 percent, while the agency's investment in wind technology should remain flat and its hydroelectric program could shrink from $59 million to $20 million.
With stimulus funds still available and next year's budget likely to grow, it's an exciting time for geothermal energy research and development, said Doug Hollett, program manager for the Energy Department's Geothermal Technologies Program. "The sweet spot of that is really 2012 and 2013. That's when everything is happening."
About two-thirds of next year's federal budget for geothermal research and development will be dedicated to EGS. That's above and beyond the $60 million already committed to a total of six full-scale EGS experiments throughout the West, of which The Geysers' project is just one. "The full potential of the EGS program, attaining those really exciting numbers, is really predicated on the R&D sector," Hollett said. "The better job we do, the faster it'll happen."
But the United States isn't the only country racing to perfect enhanced geothermal systems. France, Germany, England, and Australia have also launched projects — though roadblocks have so far outnumbered breakthroughs. In at least one respect, The Geysers are again out front. "This is the first commercially successful EGS project in the world," said Calpine Senior Geologist Mark Walters. "There is no EGS project in the world that produces enough fluid to be economic. ... So we believe we've already met the Department of Energy's goal."
Granted, the project is commercially successful only in theory. Calpine won't technically make any money off the new well — which should be able to produce 5 megawatts — until a utility agrees to buy the power at a price that will provide a return on its investment. Nor will the company proceed with a dedicated power plant nearby and begin to extend its reach into the undeveloped northern part of The Geysers — where EGS technology could help pull hundreds of megawatts out of the ground — until a power purchase agreement is inked. Yet no utility has been forthcoming.
The reason? Competition from natural gas, which provides nearly a third of the nation's power. Prices have plummeted due to the glut of gas being produced from shale rock by fracking across the country, a process implicated in a string of environmental and human-health problems. Natural gas prices hit a ten-year low this spring, dipping below coal for the first time in history. Today the fuel is nearly 50 percent cheaper than it was a year ago.
The result has been a cooling effect within the entire geothermal industry. The same thing occurred during the natural gas boom of the 1980s, which ended a period of rapid growth and caused government investment in geothermal to virtually disappear.
As Calpine waits to successfully conclude its EGS experiment, other demonstration projects supported by the Department of Energy trail closely behind. These include two Nevada projects costing $6.8 million and $7.5 million, one in Idaho ($10.6 million), and another in Oregon ($43.7 million). Each is at a different stage, but significant findings are due across the board within the next year or so — except at the final project, a $24.8 million Alaska well that's temporarily on hold due to funding and technical issues.
Beyond Calpine's experiment, the one being developed by Seattle company AltaRock at the Newberry Volcano in central Oregon is furthest along — and potentially the most impressive. It's the only one of the six to be built from scratch, rather than at an existing geothermal field or well. If it works, it will help prove that EGS is the key to unlocking a vast cache of hot, dry rock around the world. Come October, when AltaRock performs a flow test to determine the volume of steam it can pull from the well, it'll know for sure.
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