In the quest to reduce carbon emissions, scientists and companies usually try one of two main ways to address the issue. They either focus on replacing carbon-emitting energy sources with “clean,” renewable ones, or they explore ways to reduce the amount of carbon pumped into the atmosphere from conventional sources.
Now, researchers at the University of Minnesota have thought of a way to do both at once — by combining geothermal power generation with carbon sequestration.
Generating geothermal electricity requires drawing incredibly hot water from rock deep underground and using it to turn turbines. Typical carbon sequestration methods pump carbon dioxide deep — you guessed it — underground where it can’t escape into the atmosphere and warm the climate.
The new method fuses the two by replacing the water used in geothermal electricity production with compressed carbon dioxide.
This technique, which its inventors are calling the CO2-plume geothermal system (CPG), could have advantages over traditional geothermal power generation. First, carbon dioxide can more easily penetrate porous rock than water, making it more effective at extracting heat. That also means that the technique could be used in places where conventional geothermal can’t.
In a press release, one of the researchers, graduate student Jimmy Randolph, said,
“This is probably viable in areas you couldn’t even think about doing regular geothermal for electricity production,” Randolph said. “In areas where you could, it’s perhaps twice as efficient.”
Another benefit of this new method (which is only at the theoretical stage) is that carbon dioxide won’t dissolve the minerals it is traveling through as easily as water does. This means that CPG could avoid the “short-circuiting” problem of conventional geothermal systems, which occurs when the fluid gets blocked.
Lastly, the technology can extract even more natural gas and oil from partially depleted reservoirs.
Randolph and fellow researcher and geology and geophysics professor Martin Saar published their research in the May 19th issue of Geophysical Research Letters, and have applied for a patent. They intend to launch a company that will commercialize the technology.
Photo: Krafla geothermal power station by Ásgeir Eggertsson, via Wikimedia Commons
via Popular Science