Ormat’s test of EGS ‘a game-changer’
April 25, 2013
Ormat Technologies Inc. hopes to quickly take advantage of new technology it has successfully tested at its Desert Peak 2 geothermal site in Churchill County.
Called enhanced geothermal system or EGS, the new technology will let Reno-based Ormat reap more energy from existing sites. Eventually, EGS may be used to create geothermal sites where none exist today, vastly expanding the geothermal landscape and reducing the risk and costs for the entire industry.
“We’re very excited and think we can replicate at additional sites immediately,” says Paul Thomsen, Ormat’s director of policy and business development. “If we had an available drill rig at a site with an unproductive well, we would do it today. There are no barriers to replicating what we’ve done.”
With EGS technology, developers can enlarge existing fractures to reach and expand a nearby reservoir, as Ormat did in its test, or push fractures in a rock and use injected water where none exists to produce the steam needed to produce electricity.
Ormat’s EGS test, which was carried out with a team of public and private partners including the U.S. Department of Energy, Lawrence Berkeley National Laboratory and GeothermEx and TerraTek, two Schlumberger companies, was a decade in the making.
The Desert Peak site was chosen, said Thomsen, because it is “geographically benign,” or remote, yet close to an urban hub with an airport to accommodate the many professionals it required to conduct. The test was carried out on a previously drilled well that was never productive. In the end, Ormat produced an additional 1.7 megawatts of electricity using EGS.
“This is why this is a game-changer,” says Thomsen. “For a cost lower than drilling a new well we were able to resurrect this well and salvage the capital we had sunk into it. … Capital costs are what we sell the power for, so by lowering capital costs we hope to offer lower-cost electricity.”
Geothermal sites require heat, permeability and water. The presence of all three is not always obvious, and the spots where it is apparent, such as geysers, were developed by the industry years ago. Finding the right conditions is increasingly difficult. About 40 percent of the wells drilled now prove to be useless.
“About 80 percent is hidden, there is no geyser or hot spring,” says Karl Gawell, executive director, Geothermal Energy Association in Washington, D.C. “They are risky to find. You start to drill and miss the reservoir by eight feet, you might as well have missed it by eight miles.”
Thomsen says the Ormat test demonstrated that the cracks could be induced in the right direction, a key first step for EGS.
The DOE says Ormat’s EGS trial is the first in the nation to be connected to the electrical grid.
Two other EGS tests are ongoing, the Geysers site in central northern California operated by Calpine Corp. and the Newberry site in Bend, Ore., run by AltaRock Energy Inc. AltaRock also has an EGS exploration methodology site in Dixie Valley, northeast of Fallon.
Susan Petty, AltaRock president and chief technology officer, says the Seattle-based company is currently analyzing data collected in Dixie Valley and will publish a report in the fall. She says using proprietary technology, the company can triple or quadruple the production of an existing well, and bring the cost of EGS, which she says currently costs more than conventional geothermal production, in line with existing methods.
Petty says another key is bringing EGS to areas without naturally-occurring geothermal to provide a constant renewable energy source.
That, says industry representative Gawell, could be another game changer for geothermal because it can act as a both a constant source of energy, called baseload, or as a quickly ramped up stopgap for intermittent sources like wind and solar, called firming power.
Right now, with its abundance and low but fluctuating costs, natural gas is looked to as a firming source. But Gawell says geothermal, if more widely available, would be a better source because there is less downside to quickly powering up geothermal.
“Geothermal can ramp up without putting pressure on the gas supply,” says Gawell. “It’s not the way people have thought about geothermal, as both firming and flexible. Firming power is going to be very important.”