The US Air Force plans to power a base in Texas with a revolutionary geothermal technology being pioneered by a Canadian start-up that claims it can deliver limitless clean energy directly from the Earth’s core.

Eavor announced today that the US Department of Defense has handed it a contract to use its trademarked Eavor-Loop generated geothermal energy to power the Joint Base San Antonio facility in Texas.

Eavor says it will take the lead on the pilot project for its technology while being guided by the Air Force Office of Energy Assurance. It is also partnering with US exploration and production Chesapeake Energy, which will provide technical and operational expertise.

Founded in 2017, Eavor claims it can generate gigawatts of baseload and dispatchable renewable energy anywhere in the world for less than $50/MWh by the end of the decade by harnessing the power of the Earth’s core.

Eavor proposes that by drilling a hole several kilometres down – as the oil and gas industry sometimes does – and pouring water down it, it can immediately generate steam to power electricity-generating turbines. This is because the Earth’s temperature rises around 30°C every kilometre down – double that in certain volcanic hotspots.

Eavor’s crucial innovation compared to other geothermal projects is then turning that hole into a closed loop. Cold water is poured down one end of this loop and will turn to steam as it travels horizontally along kilometres below ground, before returning up another pipe to the surface.

Eavor says that not only would this loop generate constant energy but it would essentially power itself as the cold water is constantly heated underground before the heat is extracted and it cycles round again, without the need for a pump – a phenomenon known as a thermosiphon.

And the technology is no longer theoretical, with Eavor claiming to have “flawlessly” operated a demonstration facility in Alberta, Canada, since 2019.

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Oil giants BP and Chevron threw their weight behind Eavor in 2021 when they became its part-owners. More recently Eavor received backing from Japanese giant Chubu Electric Power, while German Chancellor pledged to boost the technology during a visit to one of its plants that is under development in Bavaria.

Eavor says that, with Department of Defence funding for the feasibility study, it will immediately start work to test out the “geothermal resource” near the San Antonio base.

Once completed, Eavor says its system can “fortify defence infrastructure” by delivering clean energy “regardless of electrical grid disruptions.”

Ravi Chaudhary, assistant secretary of the Air Force for Energy, Installations, and Environment, said that, "in an era of strategic competition with China," US installations are "no longer a sanctuary from the full spectrum of threats."

“We need to ruggedise our installations with redundant energy systems and make use of clean energy sources that reduce our fuel demands."

He continued that geothermal sources "strengthen our energy grids and give us the ability to isolate threats before they impact our operations. This type of capability will translate into victory in a high-end fight.”

John Redfern, Eavor president and CEO, said he believes the pilot “could be a role model for future bases, both on the national and international scale” and that it is a privilege to work with the US government and Chesapeake in the “pursuit of energy resiliency, security, and autonomy.”

Chesapeake Energy president and CEO Nick Dell’Osso said his company is “uniquely suited for subsurface engineering, surface regulatory and impact mitigation and geologic resource characterisation.”

Speaking to Recharge previously, Redfern said that when he first heard the idea for the technology he thought it was “the dumbest idea I’d ever heard” before finding out that it was actually viable (see panel below).

Michael Liebreich, the founder of Bloomberg New Energy Finance, who is chairman of Eavor's advisory board, told Recharge that, if it can be delivered affordably, the technology is “pretty damn close to the holy grail as you can get.”

As well as the Eavor partnership, the Department of Defense has handed a contract to another company, Zanskar Geothermal & Minerals, to use its AI-enabled platform for identifying geothermal resources at two other air bases.

Origins of the Eavor-Loop

A typical geothermal power plant works by drilling down into a naturally occurring underground reservoir of hot water, normally in volcanic regions. This hot water is pumped to the surface and turns into steam when it returns to atmospheric pressure, driving an electricity-generating turbine. The steam is then cooled and the cold water is pumped back into the underground reservoir to be reheated.

A so-called low-enthalpy geothermal energy (LEGE) plant has similar principles but does not utilise underground hot-water reservoirs — it simply pumps water down to a depth of 1-5km and uses the hot rock to heat the water, which is then pumped back to the surface to power an organic rankine cycle (ORC) electricity-generating system. But according to Redfern, LEGE has never taken off because the amount of energy needed to pump the heated water to the surface and later reinject it equates to 50% or more of the electricity the plant generates.

The idea for Eavor-Loop came from the company’s co-founder and now chief business development officer, Paul Cairns, during a chat with Redfern in 2017 about how suspended oil wells in Alberta could be re-used for profit — a conversation which then turned to LEGE.

“Luckily for us, my co-founder wasn’t an engineer, he wasn’t a scientist, he was a finance guy, but a creative one, and so unencumbered by geoengineering knowledge. He said, ‘why doesn’t low-enthalpy geothermal energy work?’ And I said, ‘because of the parasitic pump load that uses about 50-80% of the power produced, so little energy is produced’.

“He says, ‘well, to get around that, why don’t we just drill down two wells and connect them horizontally [below ground] and we’ll connect them on the surface and make this big loop — wouldn’t that flow better?’

“And I thought it was the dumbest idea I’d ever heard in my life… incredibly inefficient [and] capital intensive.”

But engineers such as Matt Toews, who is now the company’s chief technical officer, pointed that such a configuration would not only eliminate the parasitic pump load but would in fact pump itself due to the thermosiphon effect. This is because cold water is denser than warm water, so the cold essentially pushes the warm water towards the surface.

“And that got us excited…. This is something where we can actually make a difference. This is the Holy Grail.”