Hotrock Energy Research Organization Expands Geothermal as Coal Plants Close

CleanTech Innovation Showcase Presenting Company Recap: Hotrock Energy Research Organization (HERO)

By Steve Gerritson

CleanTech Alliance Contributor

Most people are unaware that the U.S. leads the world in the use of geothermal energy for electricity production. Even so, the potential is vast, particularly in the western U.S. Susan Petty, President of Hotrock Energy Research Organization (HERO) and a longtime officer with AltaRock, a geothermal company, sees an opportunity to expand this clean source of energy as old coal-fired power plants close. She shared her insights at the 2017 CleanTech Innovation Showcase.

Old coal plants are just not economical to modernize, and the typical pathway is to replace them with natural gas plants. While cleaner than coal, they are still fossil-fuel burners, however, and at least some of the old plants could be switched to geothermal.

Today’s geothermal process includes drilling a well, cracking deep rock, and injecting water, which is heated by the natural thermal content of the earth. The water is then brought up as steam, where it runs a turbine to generate electricity. The cooled water can then be reinjected, heated, and brought up again.

Geothermal energy as a substitute for coal requires a lot of acreage, and so would work best when the coal plant is co-located with a mine. Hotrock’s hope is to start with a pilot project and replicate successes by testing new technologies, while conducting education and outreach. They are also looking at thermal storage options. HERO is organized as a nonprofit, since power prices are very low in the Northwest, and so they can set up a revolving loan fund for testing new technologies.

The process for a particular site would be as follows: Phase I is a feasibility study, looking at the potential for geothermal at a given location; Phase II is a pilot plant of about five to 15 megawatts; and Phase III is a commercial-scale facility of 100 megawatts or more. They hope to begin field testing at one of the minemouth plants (Boardman, OR or Colstrip, MT) on different stimulation methods.

HERO’s goals are to replace fossil fuels with a clean, baseload alternative; and to save the jobs of the workers at the coal plants slated to close.