To learn more about the CarbFix project, and to find out how it all started, I spoke to the lead author of the paper, Prof Juerg Matter.
Geothermal power plants are generally much cleaner than coal-fired plants, but because they pump volcanically-heated water from deep underground to the surface, they also release (mainly) carbon dioxide (CO2) and hydrogen sulphide (H2S).
Most carbon storage projects require the H2S to be removed from the mixture (nicknamed ‘sour gas’) before storing, which can be an incredibly expensive process. But Matter and his colleagues found that they didn’t need to – they could sour gas with water directly, producing a slightly smelly, fizzy, acidic liquid that could be reinjected 400-500m down into the rocks.