Targeting geothermal power generation with well based heat exchanger

Salton Sea and the SouthernValley, California (source: flickr/ Doc Searls, creative commons)
Alexander Richter Alexander Richter 20 Feb 2019

U.S. company GeoGenCo is targeting geothermal power generation tapping heat by non-producing wells with a well-based high-performance heat-exchanger to produce electricity, with a pilot plant to start operating in mid-2020.

U.S. based GeoGenCo, LLC has announced that it has completed their semi-final designs for their next generation True Geothermal 20-MW power plant in Imperial Valley, CA. GeoGenCo has a 15 MW Power Purchase Agreement with Imperial Irrigation District (IID) and expects to be providing power by June of 2020.

Jim McIntosh (Mac), GeoGenCo’s CEO and COO states, “The project is identified as True Geothermal because all current geothermal projects require substantial amounts of water or steam as part of their power generation process. and are therefore, more appropriately known as hydro-geothermal since water is a mandatory part of the geothermal process (either in the form of brine or steam) for both the extraction of heat and for the disposal of the residual brine.”

True Geothermal does not utilize any water in their power generation process.  Rather than extracting the geothermal fluids, a high-performance heat exchanger is inserted into an existing (but non-performing) geothermal well where only heat is extracted from the geothermal formation, not from water, brine or steam.  While a permit application for approximately six acre-feet of water has been filed, about one third of this water will be utilized for dust control and the other two thirds reserved for emergency fire-fighting purposes. Zero water will be utilized for the power generation process.

A geothermal plant can require an average of 800 to 1,000 acre-feet of water per MW per year. A 50 MW geothermal power plant could therefore require between 40,000 and 50,000 acre-feet of water per year.  This translates to between 13 and 16 billion gallons of water, which could otherwise be utilized for other purposes such as agricultural. This a remarkable improvement for US states including California, where reliable 24/7 energy such as geothermal is needed to meet their Renewable Portfolio Standards goals. True Geothermal will directly coincide with California’s law requiring 50 percent of the state’s power to come from alternative energy such as geothermal energy by 2050.

GeoGenCo’s VP of Engineering Dr. Theodore (Ted) Sumrall points out, “GeoGenCo’s non-water utilizing Geothermal Power Generation technology can also take advantage of previously drilled geothermal wells that are considered ‘non-producing’ due to factors such as insufficient heat, lack of brine or steam flow, or insufficient geo-pressure. This is not only a major cost savings, but also a major risk reduction benefit to the process.”

While hydro geothermal power has the smallest land use footprint of any renewable power (an average of 4.5 Acres/MW or less than 10% of solar power), True Geothermal has less than half the footprint of hydro geothermal. This is a true carbon neutral production cycle power generation system which is extremely innovative and will solve a host of problems traditionally associated with traditional hydro geothermal power generation and result in geothermal becoming much more widely used than in the past.

Source: Company release