New Google geothermal electricity project could be a milestone for clean energy

From the article:

Google is partnering with startup Fervo, which has developed new technology for harnessing geothermal power. Since they’re using different tactics than traditional geothermal plants, it is a relatively small project with the capacity to generate 3.5 MW. For context, one megawatt is enough to meet the demand of roughly 750 homes. The project will feed electricity into the local grid that serves two of Google’s data centers outside of Las Vegas and Reno.

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The project has been in the works since 2021 [...]

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This new project actually was built on the outskirts of an existing geothermal field where, in Terrell’s words, “there’s hot rock, but there’s no fluid.” To generate geoethermal energy there, Fervo had to drill two horizontal wells through which it pumps water. Fervo pushes cold water through fractures in the rock, which heats it up so it can generate steam back at the surface. It’s a closed-loop system, so the water gets reused — an important feature in a drought-prone region like Nevada.

Fervo also installed fiber optic cables inside the two wells in order to gather real-time data on flow, temperature, and performance of its geothermal system. These are tactics gleaned from the oil and gas industry to tap energy resources that otherwise would have been out of reach.

There's also an AP News article with more detail, but annoying ads:

Fervo is using this first pilot to launch other projects that will deliver far more carbon-free electricity to the grid. It’s currently completing initial drilling in southwest Utah for a 400-megawatt project.

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Drilling technology and practices drastically improved during the shale boom that transformed the United States into a top oil and gas producer and exporter. But there has been very little tech transfer from the oil and gas industry to geothermal, said Sarah Jewett, vice president of strategy at Fervo.

“They were using all of the old, for lack of a better word, janky stuff from old-school oil and gas development,” she said. “We basically just went to the oil field service companies and said, ‘Give us all your best stuff.’ And we have been using all of the modern drilling technology to do our development.” That has led to far greater efficiency and lower cost, she said.

In a presentation at ClimateTech 2023 at the Massachusetts Institute of Technology, Latimer talked about how Fervo is pioneering horizontal drilling in geothermal reservoirs. In Nevada, Fervo drilled some 8,000 feet down, turned sideways and drilled about 3,250 feet horizontally.

By drilling horizontally, Fervo can reach much more of the hot reservoir, instead of having to have to drill many vertical wells.

Fervo pumps cold water down an injection well, then over hot rock underground to another well, the production well. The path between is created by fracking, or fracturing the rock. The water heats up to nearly 400 degrees Fahrenheit (200 degrees Celsius) before returning to the surface. Once there, it transfers its heat to another liquid with a low boiling point, creating steam. The pressure of steam expanding spins a turbine to produce electricity like in a coal or natural gas-fired plant. The geothermal water, now cooled, is put back down the injection well to start the cycle again, in a closed-loop system.