Turning Old Oil Fields Into Renewable Power Plants, Thanks To CO2

Heat Mining's recipe for cheap carbon reductions: Take CO2 we're already making, pump it into oil fields instead of into the sky, and voila, you have a source of geothermal power.

Two dirty energy sources--coal and oil--are having a renewable energy lovechild in the form of a new startup called Heat Mining.

The company starts with CO2 captured from coal-fired power plants or other polluters. The CO2 is shipped to an old oil field, which happens to be the site of most existing underground carbon storage efforts. After an oil field is tapped out, its owner will often inject CO2 into the well, which will squeeze out the last drops and increase production.

When the last drops of oil are gone, that's where Heat Mining’s tech can step in. Using the oil field’s existing infrastructure to store CO2, the company will create a new geothermal power plant. The CO2 is naturally heated underground, then runs up into the plant, where it can produce electricity that’s around 3 to 4 cents a kilowatt hour, as cheap natural gas.

It all adds up to a cost-effective way to reduce levels of CO2, the researchers say. “You don’t need to talk about crippling the economy in order to eliminate atmospheric CO2 emissions. That’s what everybody says is a sticking point, and there’s no reason we need to do that,” said Jimmy Randolph, chief technology officer for Heat Mining and a research associate at the University of Minnesota. “Our technology is a very solid way to make an economic return on CO2 elimination, and there are other technologies out there as well. There’s no reason we can’t do this at large scale and very effectively.”

For Randolph, the technology is a way to tackle climate change that makes business sense today, at a time when political and policy changes are not really happening.

The Heat Mining tech can also be used in places where conventional geothermal power wouldn’t work, because it’s more efficient and can work in more climates. “Essentially, it can go anywhere where there’s a suitable aquifer for CO2 injection, which constitutes something like 40% to 50% of North America,” says Randolph.

Obviously, pumping gas into the ground isn’t entirely without risk; just days ago, a new study found that in some places in Texas there was a correlation between CO2 used in oil fields and small earthquakes. At the same time, the study also suggested that location mattered, since other sites in Texas didn't have problems. Randolph says their company will be targeting places that aren't seismically active, and using techniques that mining companies have proven to work over the last few decades.

Heat Mining plans to begin construction on their first demonstration plant early next year and hopes to scale up once the pilot shows that everything operates as expected. There's a lot of potential, the researchers say. In the United States alone, they estimate they could produce 10,000 megawatts of power (enough to power roughly 10 million homes) using existing oil fields alone.

[Image: West Texas Pumpjack via Wikipedia]

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