The roar of the Zambezi River is deafening, as millions of gallons of water cascade down, crashing against the rocks and tumbling down the rapids. Yet, in the Zambian bush, another sound can be heard – a distinctive, high-pitched hum of Bitcoin mining machines.
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03-31, 2025"That's the sound of money!" says Philip Walton with a smile, as he checks a shipping container packed with 120 computers, busily performing complex calculations to verify Bitcoin transactions. In exchange, they automatically receive Bitcoin rewards from the network. Located in the far northwest corner of Zambia, near the border with the Democratic Republic of Congo, this is the most unusual Bitcoin mine I have ever visited.
Water and electronics don't usually mix well, but it is the proximity to the river that has drawn Bitcoin miners here. Philip's mine is directly connected to a hydroelectric power plant, which channels a portion of the Zambezi's turbulence through massive turbines to generate a constant stream of clean electricity. More importantly for Bitcoin mining, the electricity here is incredibly cheap.
These low electricity prices make it commercially worthwhile for Philip's Kenyan company, Gridless, to transport containers full of sophisticated Bitcoin mining computers on a bumpy, 14-hour drive from the nearest major city to set them up here. Each machine earns approximately $5 (£3.90) per day. If the price of Bitcoin goes up, the earnings will be higher; if the price goes down, the earnings will be less.
Philip occasionally glances at his smart watch, its home screen displaying the fluctuating curve of Bitcoin's dollar value. Currently, one Bitcoin is worth around $80,000, but Philip says that even if the price of Bitcoin falls, they can still make a profit due to the site's cheap electricity and their partnership with the energy company. "We recognised that to have better mining economics, we needed to partner with the energy companies here and give them a revenue share. So we're willing to come to such remote locations because that allows us to effectively get cheaper power," he says.
The Zengamina hydroelectric power plant is vast in scale, but technically it is a microgrid – an isolated power supply providing independent electricity to the local community. It was built in the early 2000s, thanks to $3 million raised from charitable donations. Daniel Rea, a British-Zambian, has been in charge of running the site since his missionary family led the construction project, primarily to power the local hospital.
Now, it provides electricity to about 15,000 local people, but the project has struggled to break even due to low uptake from the community. Allowing Bitcoin miners to set up shop here has had a transformative impact on the business. "We were wasting more than half of our generation capacity every day, which also meant we weren't getting the revenue from it to pay for our operating costs. We needed a major power user in the area, and that's where the partnership with Gridless made a difference," says Daniel.
The Bitcoin mine now accounts for about 30% of the power plant's revenue, which has allowed them to lower electricity prices for the local town. Of course, Bitcoin and its economics are not what the people of Zengamina are concerned about.
The town itself is a few miles from the power plant, consisting of a few dozen shack-like buildings scattered around a crossroads. Only one shop has a refrigerator, and a dozen children huddle around a communal computer, taking turns to choose a song to play, which the adults hear as they go about their busy day. Although the hydroelectric plant came online in 2007, it took several more years to connect it to the local town, and then even longer to connect individual homes and businesses.
As a result, some people like Damian, a barber, are still enjoying the novelty of having electricity, which only arrived a year and a half ago. "Before I had electricity, I had nothing, I couldn't do anything. After electricity, I bought everything at once." He's not joking. At night, his tiny barber shop is brightly lit, playing music videos, hung with strings of Christmas lights, and buzzing with the sound of electric clippers. Like moths, young people gather at his barber shop, like a youth hostel.
"Electricity has changed my life," he says with a smile. "The money I'm making from the barber shop now is helping me pay for my school fees again." For Damian, embracing electricity was purely a business decision. At home, he shares a single light bulb with the two rooms in his small house.
Elsewhere in town, sisters Tumba and Lucy Machai sit at the crossroads, watching the world go by. Like many young people, their eyes are glued to their phones. "Before the town had electricity, it was basically just bush here," says Lucy. They say that the little electricity they had before came from small solar panels. "No refrigerators, no TVs, no mobile network," says Tumba.
"Electricity has completely transformed people's lives here," Lucy adds. "We can charge our phones, we have the internet. We can communicate with each other." Not many people here know or care about the role that the Bitcoin mine is playing in helping the hydroelectric plant stay afloat.
But soon, they will see that shipping container rumbling through town again, heading to another location. The Zengamina hydroelectric company has secured a large investment to help them expand to more villages and connect to the national grid. Soon, the surplus energy that the mine is using will be sold back to the national grid, and mining in Zengamina will no longer be profitable.
Philip and his team are optimistic about this, insisting that it's good news. They've had a successful few years here, and ultimately they're happy to have helped Zengamina. And of course, to have earned a decent Bitcoin profit. The company says that there are plenty of places with so-called stranded energy where they can set up Bitcoin mines next to them.
Gridless already has six such sites in three different African countries. North of Zengamina, another Bitcoin mine is using surplus energy from a hydroelectric plant run by the Virunga National Park in Congo. The park says that this helps to fund conservation projects. But Gridless is now planning an ambitious next step – to build its own hydroelectric plants from scratch, to mine Bitcoin and bring electricity to rural areas.
Jeannette Mawinza, the company's co-founder, says that the company is busy raising tens of millions of dollars for the project. They are focusing on so-called run-of-river hydro models like Zengamina, and the African continent has abundant "untapped hydro potential," she says. "Consumer-driven, adaptable energy models are critical for scalable, affordable, and sustainable energy access that can meet the needs of African communities," she explains.
The company is not a charity and argues that only Bitcoin can ensure the long-term economic viability for developers and investors. However, finding locations for new plants or utilising existing ones is the easy part. The company still faces resistance from some authorities and companies who see Bitcoin as an energy-intensive and selfish use of electricity that could otherwise be used by rural people.
But the company insists that the incentive is always to sell to the highest bidder, and they say that this is always the local community. History tells us that without incentives or rules, large-scale Bitcoin mining can put a strain on public grids. In 2020-2021, a mining boom in Kazakhstan increased the country's energy consumption by 7%, before the government cracked down and clipped the wings of the nascent industry.
In the US – the new Mecca of Bitcoin mining – conflicts between miners, locals, and residents are common when electricity demand is high. Authorities have reached agreements with some mining giants to ensure that they shut down their warehouses full of computers when the grid needs balancing. For example, the Greenidge gas power plant in New York, which was renovated to mine Bitcoin, was required to shut down its mining operations in January to provide power to the grid during a cold snap.
If President Donald Trump's ambition to "mine, mint, and make" Bitcoin in America is to be realised, such agreements will need to be widespread. The industry's environmental impact is also a major concern. It is estimated that Bitcoin mining consumes as much energy as a small country like Poland.
But according to researchers at Cambridge University, which produces an annual estimate of Bitcoin's energy consumption, it is currently shifting towards a more sustainable energy mix. Setups like Zengamina are just a small part of the overall mining picture. But they are also a rare example of a controversial industry creating something more than just digital currency.
