Can This Company Use Earth's Heat to Suck Carbon from the Sky?

An anonymous reader shares this report from the Washington Post:Sucking carbon dioxide out of the sky - or "direct air capture," as it is known by experts and scientists - is a bit like a time machine for climate change. It removes CO2 from the atmosphere and stores it deep underground, almost exactly the reverse of what humanity has been doing for centuries by burning fossil fuels. Its promise? That it can help run back the clock, undoing some of what we have done to the atmosphere and helping to return the planet to a cooler state. The problem with direct air capture, however, has been that it takes energy - a lot of energy.... But if the energy powering that comes from fossil fuels, direct air capture starts to look less like a time machine than an accelerator: a way to emit even more CO2. Now, however, a company is working to combine direct air capture with a relatively untapped source of energy: Heat from Earth's crust. Fervo Energy, a geothermal company headquartered in Houston, announced on Thursday that it will design and engineer the first purpose-built geothermal and direct air capture plant. With the help of a grant from the Chan Zuckerberg Initiative, the company hopes to have a pilot facility online in 3 to 5 years. If it works, it will be a way to produce carbon-free electricity, while reducing CO2 in the atmosphere at the same time. In short, a win-win for the climate. "You have to have your energy from a carbon-free source" for direct air capture to make sense, said Timothy Latimer, the CEO of Fervo Energy. "Geothermal is a great match...." Geothermal wells don't, of course, get anywhere close to Earth's core, but a geothermal well drilled just 1 to 2 miles into hot rocks below the surface can reach temperatures of up to 1,000 degrees. Water is pumped into the well, heated and returned to the surface, where it can be converted into steam and electricity. Even after generating electricity, most geothermal plants have a lot of waste heat - often clocking in around 212 degrees. And conveniently, that happens to be the exact temperature needed to pull carbon dioxide out of an air filter and bury it underground. The article notes a study which found that if air capture were combined with all the geothermal plants currently in America, the country "could suck up around 12.8 million tons of carbon dioxide every year." And "Unlike wind and solar, a geothermal plant can be on all of the time, producing electricity even when the wind isn't blowing or the sun isn't shining."

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