Researchers from the University of Minnesota’s Department of Earth Sciences have developed an approach to extracting geothermal energy more efficiently while reducing atmospheric carbon dioxide at the same time.
The new approach, which the researchers call carbon dioxide-plume geothermal system or C.P.G., uses high-pressure carbon dioxide to produce power from the Earth’s heat.
In conventional geothermal power technology, water is used to tap into the Earth’s heat. Hot water or steam is extracted from underground rock formations then used to turn turbines to produce power.
The C.P.G. system also used the Earth’s heat but instead of water, uses high pressure carbon dioxide as the underground heat-carrying fluid.
“This is probably viable in areas you couldn’t even think about doing regular geothermal for electricity production. In areas where you could, it’s perhaps twice as efficient,” said Jimmy Randolph, a graduate student and co-developer of the technology.
Another benefit of using pure carbon dioxide as the heat-carrying fluid is that it reduces the risk of blockage in the flow of fluid in a geothermal system because it does not dissolve the material around it like hot water does.
In addition to harnessing geothermal energy more efficiently, C.P.G. can sequester carbon dioxide deep underground where it cannot contribute to climate change.
Mr. Randolph along with Earth sciences faculty member Martin Saar got the idea for C.P.G. when they were conducting research on geothermal energy capture and separately on geologic carbon dioxide sequestration.
They received a grant from the Initiative for Renewable Energy and the Environment, which they used for paying the preliminary computer modelling and to gather experts needed for the research. It also helped leverage a $1.5 million-grant from the United States Department of Energy to explore subsurface chemical interactions involved in the process.
Accessibility of geothermal energy has been a key issue in the United States where it generates only 4.68 per cent of the total renewable energy output of the country.
Accessibility problems when it comes to geothermal are brought about by simple reasons such as the challenge of hard rocks on the surface which are tough to drill through and the fact that tapping into the energy source takes time.
With the researchers’ claims of extracting geothermal energy much more efficiently with the technology, this could help the country’s geothermal output. (L.J. Polintan)
Contributed by EcoSeed
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