When considering renewable energy, most evaluations look primarily at two sources: wind and solar. Both sources are growing rapidly. Both sources are getting progressively cheaper. In recent years, both sources have seen their cost per megawatt hour fall below that of coal, helping to persuade utilities to switch to renewable sources and lowering demand for fossil fuels. In fact, it’s now cheaper to build new solar or wind power than it is to just keep an old coal plant running.
Hydro power is often mentioned, but only in the sense that while it plays a significant role in the current energy portfolio, there are few options for expansion. While wind and solar have been racing up, hydroelectric production has declined.
And then there’s geothermal power. In 2000, geothermal produced twice as much electricity as wind. In 2023, wind produces 25 times as much electricity as geothermal. Limitations on geothermal kept it restricted to a few locations as thousands of wind turbines spread across the nation. But a new breakthrough may have greatly expanded the potential growth of geothermal power. And all it takes is … fracking.
The Energy Department has nothing but glowing things to say about geothermal power. Geothermal plants are smaller than fossil fuel plants and far smaller than fields of photovoltaic panels for solar. They can operate continuously, without concerns about weather (or the pesky fact that the sun hides out for half the day). They have a smaller ecological footprint over their lifetime than a field of wind turbines. That makes it easy to understand why the DOE projects as much as 60 gigawatts of electricity-generating capacity from 17,000 small geothermal power plants by 2050.
But right now, the United States generates just 3.7 gigawatts of geothermal electricity. That’s the most in the world, but it’s still not a lot. The reason is simple. Existing geothermal plants require two things: a source of heat that’s not too deep to make drilling down to it reasonable, and rocks that are permeable enough to allow water to be pumped through them. Cold water goes down, hot water comes out, and the result is a gain in energy that comes right out of the Earth.
However, there aren’t all that many locations that have the right conditions. In many places, drilling down far enough to find an appropriate level of heat means encountering rock formations that are too dense and impermeable to allow water to flow. The energy is down there, but getting it out becomes a problem.
As Bloomberg reports, Houston-based startup Fervo Energy has completed a demonstration of its commercial geothermal power production system. That demonstration plant, located in Utah, generated about 3.5 megawatts of electricity (enough for about 2,500 homes) for a period of 30 days, and it did so in an area that was previously thought to be unsuitable for geothermal energy.
How Fervo did this will be familiar to anyone who has followed the oil and gas industry over the past two decades: They did it through fracking.
Fervo’s system is what’s been called an “enhanced geothermal system,” also known as EGS. A trio of pilot systems have been built in the past decade, but Fervo is the first to construct what seems to be a practical solution at a commercial scale. The pilot plant, which has been named “Project Red,” will connect to the grid later this year and reportedly provide power for a Google server farm as part of a larger agreement between Fervo and Google’s parent company, Alphabet.
Fervo intends to extend energy production at the test site in Utah with additional wells and generators. It is currently planning to produce 400 megawatts of power at this location by 2028. It’s currently in the process of planning and permitting six other sites in the western U.S.
Though the technology used to open fractures at depth and allow water to pass through is very similar to the fracking used to increase oil and gas production, it should—in theory at least—have much less environmental impact. For one thing, there are many fewer wells being drilled to support one of Fervo’s plants, even a full scaled-up plant, than are used in even a single gas field. Also, the depth drilled to generate geothermal power is much greater, often several kilometers down. If the wells leading down to the “hot zone” are fully encased, it should be possible to operate these plants without the threat of polluting or depleting water tables in the area.
There are still some things to consider. The return on water injected into the system is not 100%, so over time Fervo will need a supply of water to feed down the well. And there have been issues in some locations associating fracking with small earthquakes connected to fluid injection. Both the establishment of the initial fractures and the long-term feeding of water through the system could possibly trigger similar events.
Even with these considerations, the possibility of expanded geothermal power is exciting. Many people, even strong supporters of renewable energy, have been worried about the scale of the areas needed for adequate energy production with solar and wind, and both of those systems require equally large amounts of energy storage if they are going to act as “base load” systems to meet primary energy demands.
Geothermal can act as a base load system. Additionally, Fervo insists that their plants are also flexible enough to act as “peaking plants” to meet spikes in energy demand. In a paper authored along with researchers from Princeton University, Fervo representatives insist that this flexibility of design represents another reason why their model could greatly expand the role of geothermal energy in the renewable mix.
EGS, hydraulic stimulation is used to create an artificial geothermal reservoir where one did not exist previously. Relatively shallow EGS resources underlie much of the western United States, and successful development of this technology could unlock hundreds to thousands of gigawatts of geothermal resource potential nationwide.
“Thousands of gigawatts” is obviously a lot more than the 60 gigawatts that the DOE projected from this technology.
Fervo’s plant is a single demonstration facility, and it’s just 30 days old. But it’s hard not to be excited about the possibilities.