How a Jack Dorsey-backed bitcoin miner uses a volcano in Kenya to turn on the lights in rural homes

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HELL'S GATE, Kenya — Two-and-a-half hours northwest of Nairobi by car, a small group of bitcoin miners set up shop at the site of an extinct volcano near Hell's Gate National Park.

The mine, tucked away on the edge of Lake Naivasha, is operated by a startup called Gridless and consists of a single 500-kilowatt mobile container that, from the outside, looks like a small residential trailer.

Backed by Jack Dorsey's Block, Gridless electrifies its machines with a mix of solar power and the stranded, wasted energy from a nearby geothermal site. It's one of six mines run by the company in Kenya, Malawi and Zambia, powered by a mix of renewable inputs and working toward a broader mission of securing and decentralizing the bitcoin network.

"Most people think about bitcoin and the price of bitcoin and how they can save value in it or maybe spend it," Gridless CEO Erik Hersman told CNBC during a visit to the Kenyan mine earlier this year. "That doesn't happen without the bitcoin miners and us being globally distributed."

Decentralization is a key feature of bitcoin, because it means the network isn't controlled by any entity and can't be shut down — even if a government disapproves.

Bitcoin and some other cryptocurrencies are created through a process known as proof-of-work, in which miners around the world run high-powered computers that collectively validate transactions and simultaneously create new tokens. The process requires heaps of electricity, leading miners to seek out the cheapest sources of power.

While there are more than a dozen publicly traded miners, thousands of smaller, private operations are also competing to process transactions and get paid in new bitcoin. That includes