Though bitcoin is a volatile currency, some studies have shown that extra income from bitcoin mining can help renewable energy providers scale up. In Ethiopia, home to some of the cheapest green energy in the world, nearly a fifth of all electricity sold in the country last year went to bitcoin mining companies. The income will help develop the national grid.

Not all the signs are so promising, though.

Renewable energy will only really be able to replace fossil fuels when the technology exists to store and transport it. But energy companies selling to bitcoin miners next door do not have to find ways to store it, says Jona Stinner, a postdoctoral researcher at Witten/Herdecke University in Germany who studies the environmental impact of bitcoin mining. So there is no incentive to develop novel storage facilities.

It is “not very helpful for the long-term green transformation,” Mr. Stinner says.