Scientists turned an abandoned oil well into a giant geothermal battery

There are tens of thousands of abandoned oil and gas wells around the world that pose serious environmental problems. But they can be put to good use, as researchers at the University of Illinois have done.

Lead researcher Tugs Baser and his colleagues turned one of the abandoned oil wells in the Illinois Basin into a geothermal battery. To do so, they pumped water preheated to 122 °F to a depth of about 3,000 ft into a layer of porous sandstone, which is an excellent natural thermal insulator.

The result exceeded all expectations: the natural geothermal battery retained 82% (106°F) of the heat produced for a long time. Moreover, calculations have shown that this technology can be profitable in the future – the price of 1 kW⋅h of energy stored in this way is only $0.138

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