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Greenfire Energy Replaces Water With CO2 for Geothermal Extraction


Greenfire Energy stands to prove us how good projects, as long as they’re really good, will stand out and receive funding. This project will get $2 million in funding for replacing water with CO2 in the process of extracting geothermal energy.

This sum is only a small fraction of the total $20 million the Department of Energy is making available for updating geothermal technologies. Researchers involved in the project claim the development up to the demonstration stage will cost around $32 million, so the percentage received is nothing to be excited about.

First of all, the team made up of a geologist, a chemist, an environmental specialist and an oil industry technologist has set off to a good start: they plan to use low temperature geothermal, a resource they can afford to plunge in rather than the precious water. This way carbon dioxide is also stored underground.

So the team will take advantage of CO2 deposits at an empty gas field for a test called CO2Eâ„¢. Next, they will ponder over going with a closed loop binary system for the pilot. If they decide to stick to this idea, they will use underground rocks to heat CO2 into a supercritical state. Once back to the surface, this CO2 will heat another fluid, which in turn spins turbines to produce electricity. The CO2 will circulate into the system for a while in order to generate power, but each time it does so, an amount of 5 to 60% will remain underground for good.

Using carbon dioxide instead of water is a splendid idea for a number of reasons: it is less thick and sticky than water, so one can inject it quicker into rock formations. Unlike water, carbon dioxide can be made to have both liquid and gas characteristics (the supercritical state) and is more likely to remain that way for longer, without putting any effort into it.

This results in less equipment and more efficiency at lower temperatures and shallower depths. If one can apply the process at a more superficial depth, then one saves money on drilling. Not to mention water itself! All in all, the project is clearly a win-win solution for everybody. It remains to be seen how it will get the rest of the money to do it!

[via Cleantechnica]

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