Pilot project seeks to fix Achilles heel of geothermal power

The Hill

08-05-2025

A pilot project from a team of oil industry veterans could save one of California's key clean energy resources from terminal decline.
On Thursday, energy company Greenfire announced that they had restored new life to a defunct well in The Geysers, the world's largest geothermal power station — and one that has been in a state of slow, decades-long collapse.
By means of technology that taps the heat from underground — rather than the rapidly-depleting water — the Greenfire team turned a well whose electric production had flatlined into a power producer.
That offers a potential lifeline to The Geysers, which currently generates about 630 megawatts of on-demand, carbon free electricity to Northern California — down from 2,000 megawatts in 1987.
'You can see these grey wells — they've been abandoned,' said Rob Klenner, a former oil and gas engineer who is now Greenfire's chief executive, pointing to a diagram of the site where boreholes once funneled steam — heated by friction of the faults grinding beneath California — up to spin turbines.
'There's still heat in this area, but it's kind of like a dry well,' Klenner said, comparing it to petroleum. 'Like, 'Hey, we got a little bit of oil, but not enough to make this economics, and then they shut everything in,'' Klenner said.
The reason for the decline: the ferocious pace at which conventional forms of geothermal energy can use up water.
Today, The Geysers plants use an average of 15 million gallons — 22 Olympic pools — per day. The complex's 18 power plants, spread across 45 miles, tap into the source in the form of the steam that spins their turbines.
While this largely comes from treated municipal wastewater, it nonetheless represents a significant loss of water in a famously water-stressed region — and a significant brake on the ability of so-called hydrothermal fields to produce power.
Greenfire's new power station, which sits atop a well that had also been largely abandoned for lack of pressure, takes an approach that produces power without losing water.
Rather than spinning a turbine with the physical force of superheated water — which is then lost to the atmosphere — Greenfire's team pumped in enough water to restore pressure, and then sealed the well.
Now, as the steam rises from the hot rock below, it hits the heat exchanger of a different kind of power plant called an Organic Rankine Cycle (ORC), a closed-loop system full of a 'working fluid' that boils at a much lower temperature than water.
As the working fluid moves through the pipes of the ORC, it spins a turbine and generates power — before releasing its heat into a condenser and falling, exhausted, back into the pump to start again.
Inside the well, something similar is happening, Klenner said. The rising steam dumps its heat into the ORC, and then gets reinjected into the new underground closed loop.
'It cools back down, and then we would re-inject it,' he added. 'So now there's no water coming to the surface anymore.'
He compared this system to injection wells that coax new oil out of failing oil wells — with the difference that ideally nothing leaves the ground.
As the buzz in geothermal energy increasingly focuses on 'enhanced' forms of the technology that use techniques like fracking to create artificial underground cavern networks, Klenner hopes that techniques like this one offer a low-hanging fruit to revitalize existing resources.
Proponents of enhanced geothermal (EGS) hope for geothermal drilling on a scale that rivals the oil and gas boom of the 2010s. But while Greenfire has its own EGS projects, Klenner noted that that side of the business, almost by definition, means creating electricity at new sites which planners will then have to figure out how to connect to the grid.
At The Geysers, he said, 'The infrastructure is already there. They already have the wells. They already have the power lines. Rather than going to an area where, you know, we want to go do this for the first time, we're working in an area that has everything already put together — which helps lower the cost hurdles.'
Bringing The Geysers back to its late 20th Century peak, he noted, would be the equivalent of adding a gigawatt to the grid — the equivalent of building, say, hundreds of new wind turbines, with none of the challenges that such new builds entail.
'If we can do this in existing wells, and we could simply just double production, there's large opportunity,' he said.