The administration of President Donald Trump is sceptical about much renewable energy, but not about enhanced geothermal, which is also known as next-generation geothermal. NewsBase interviewed Cindy Taff, the CEO of Sage Geosystems, a leading US enhanced-geothermal company.

Sage uses fracking, a technology first developed by the US shale industry. In 2024, Sage also announced $17mn in Series A funding, an investment round led Chesapeake Energy (now Expand Energy), an oil and gas operator that helped create the US shale gas boom.

Q: How does enhanced geothermal differ from the conventional geothermal we have in California or Kenya?

A: In conventional geothermal, you're drilling for heat and you're also looking for a large body of water to pull that heat and bring it to the surface. And so that limits you geologically, or geographically.

What we do is next-generation geothermal, or ‘hot dry rock geothermal’. You drill a little bit deeper in most cases than in conventional, but you're just looking for rock that has the heat.

Q: So it’s geothermal anywhere. And where does Sage fit into this? What do you do compared with other enhanced geothermal companies?

A: We're using a fracture system because you can create surface area to harvest the heat with fracking, whereas if you have to drill a well and lay pipe – for closed-loop geothermal – then it takes months, if not years to drill to get the same surface area. We're leveraging both the pressure and the heat, which allows us to have more net output of power.

Q: And how do you leverage the pressure?

A: We frack and fill the fractures with water, and when we need the water to come to the surface, we open a valve at surface and those fractures are wanting to naturally close, and when they do, it jets the water to the surface. It’s leveraging the elasticity of the rock and that means that we have to put less energy into the system, meaning that we're going to have a higher net output.

Q: This is where you're using technology from the oil and gas industry?

A: In fracking, there's different technologies that the oil and gas industry has proven over the last 15 years. We're fracking slightly differently than the oil and gas industry, but learning from the oil and gas industry. We don't use proppant. We hold the fractures open with pressure.

Q: Some of the pioneers of enhanced geothermal in fact come from the oil and gas industry.

A: I was at Shell for 35 years, ultimately serving as vice president of Unconventional Wells & Logistics, leading a team across five countries with an annual budget of $1bn.

Q: Why did you decide to jump into renewable energy?

A: My team was always asked to do cost estimates for geothermal wells and I noticed we never would pull the trigger. Our energy transition strategy never included geothermal. It always included solar and wind and EV charging stations, and I thought that we're an oil and gas company and one of our core skill sets is drilling wells.

Two of my ex-Shell colleagues called me, and they were looking at getting into geothermal. I knew if anybody could figure out how to make geothermal cost effective, which is the challenge, it would be these two guys. And so it was a perfect opportunity to take my skill set, and go into the energy transition. I could have gone into wind or solar, but I couldn't use my skill set as well as I could in geothermal.

Q: Can you tell us about the deal that you have with Meta, owner of Facebook?

A: We have a term sheet with Meta for 150 MW of geothermal power generation with the option for another 200 MW. We're working on with them on an exact location but it’ll be east of the Rockies. They wanted to have a virtual PPA where their data centres are taking power off the same grid, but we're not selling it directly to the data centre.

In fact, we're talking to several of the other hyperscalers. All of the hyperscalers are looking for all of the power that they can use. A couple are interested in geothermal and storage because the way they do their renewable energy is on an hourly matching basis.

Q: Would you do the storage or would somebody else?

A: We are pioneering ‘pressure geothermal’ so we use both the earth's pressure and the earth's heat. And for our storage, what we're doing is using the earth's pressure, so we'll drill a well, create a fracture, when the energy demand is low, we use that electricity to power a pump, we pump water into that fracture. We balloon that fracture and store that water under pressure and then when the demand peaks, you open a valve at the surface, you release the pressure and it turns a Pelton turbine-generator.

It's long-duration storage. It's not meant to compete with lithium-ion batteries, but if you need power duration greater than five hours, then we can beat the cost of lithium-ion batteries.

Q: Is there any danger of a seismic response?

A: The way induced seismicity works is when you produce a fluid that flows past existing faults, the fluid will lubricate the faults and make them slide, then you have an earthquake or tremor.

But we're not connecting two wells with a set of fractures, so if our fracture intersects the fault, it's like having a hole in your lung – all our fluid would be lost or our efficiencies would drop. And so we have a very low risk at induced seismicity.

Even so, for all of our locations we're working with the University of Texas, where they're monitoring for induced seismicity, and all of the data is publicly available on the Internet.

Q: When will your technology be commercially viable?

A: We have our first commercial energy storage facility already built. We're commissioning it as we speak, and then we'll be connected to the grid, the Texas grid, in September.

We’ll be doing a geothermal demonstration with the US Air Force later this year also in Texas. The first commercial geothermal facility will be most likely 2027 with Meta.

Q: What will the cost of electricity be?

A: If we are at a scale of about 100 MW, we're looking at 10 cents a kilowatt-hour. If we can get that scale above 100 MW, then we can get the cost down to 6 and a half to 7 1/2 cents a kilowatt-hour. It does depend on where you are geographically and the ambient temperature.

Q: You said to The Hill that this will be the decade of geothermal. Can you expand upon that?

A: If you look at all of the momentum that geothermal has right now, and energy is a national security issue, and energy is needed for AI. If you look at AI as an arms race, it goes back to that national security issue.

I really do think where we are currently sitting is where wind and solar were 10 or 15 years ago, and that learning curve is just going to be accelerated. I really think once we gain momentum on that learning curve, we could drive costs down. Of course, everybody wants cheap, clean power.

Q: And you're also 24/7 power, unlike wind or solar which are weather-dependent.

A: Yes, geothermal power generation provides baseload or 24/7 power.

Q: What about the political context for enhanced geothermal. What do we know about where geothermal stands with the Trump administration? Energy Secretary Chris Wright has said some favourable things about geothermal.

A:  Geothermal has always enjoyed support from both sides of the aisle. Chris Wright has also personally worked in geothermal, 30 years ago. He can articulate the difference between conventional geothermal and next-generation geothermal. So he also understands that there's companies like Sage and others drilling wells, building facilities, and that we're going to have answers in the next two or three years. Trump also specifically mentioned geothermal in two executive orders, including the one declaring that there is an energy emergency.