Grant County PUD staff members on May 12 delivered a crash course on “Enhanced Geothermal” energy to familiarize PUD commissioners with that energy source.
The high-level course will help commissioners decide whether to join Chelan and Douglas PUDs in their ongoing effort to explore the feasibility of geothermal as an around-the-clock-available, carbon-free energy source, Washington State-based Grant PUD said.
The analysis, including drilling test “wells” more than 3 miles deep, will determine if our region contains sufficient geothermal “hot spots” to convert the steam they emit into electricity for our customers.
Staff expressed optimism that conditions do exist in Grant County for “Enhanced Geothermal” technology that could one day power a steam plant capable of generating 500 or more megawatts of electricity.
If commissioners move forward, Grant PUD would share the cost of the $22 million analysis with Chelan and Douglas PUDs, which began their research several years ago and have already hired a contractor for the job.
Grant PUD’s share would be about $7 million.
Grant PUD Engineer Dave Dempsey told commissioners the process draws on lessons from gas and oil industries’ experience drilling deep wells to extract those fuels. Enhanced Geothermal uses vertical and horizontal drilling to reach deep into the rock heated by the Earth’s core several miles below the surface. Cold water is injected into the hot rock via injection pipes to create steam that rises to feed a steam turbine unit to create electricity.
But unlike “fracking,” the process used to extract gas and oil, Enhanced Geothermal targets hot rock. It’s a heat-exchange operation, not for resource extraction, Dempsey said.
The spent steam, as cooled water, would then be pumped back into the earth in a closed-loop system to replenish the geothermal source.
The process does not cool the geothermal source nor contaminate ground water, Dempsey said.
Commissioners will study the information and are scheduled to vote at their May 26 commission meeting on whether to participate in the analysis with Chelan and Douglas PUDs.
