Waterwheels are back, and they’re generating electricity
But these contraptions don't exactly enjoy wide adoption.
In the foothills of the Himalayas, a group of villagers hauled a sturdy metal waterwheel into place. Its horizontal blades soon caught the rushing water of the stream directly below it. Now the machine was spinning – and electricity began to flow.
This roughly two metre-tall waterwheel, installed in a village in Kashmir, India, was the result of years of design work and development by researchers at the Technical University of Munich (TUM), and partners.
“You have this continuous power flow,” says Michael Erhart, chair of renewable and sustainable energy systems at TUM, referring to the benefits of waterwheels. “It’s not intermittent like the radiation of the sun or wind power.”
For the Kashmiri villagers, their new waterwheel offered energy independence. It was installed alongside other renewable energy resources, including a microgrid, between 2022 and 2024. Previously, the community had had to rely on a centralised electricity grid that often let them down. “They had power cuts of weeks or even months,” says Erhart. The new renewable energy kit took the village off-grid, with a promise of resilience.
Waterwheels have been around for thousands of years. Formerly used to drive mechanical processes such as milling or hammering, they were a crucial component in the industrial revolution, only declining in popularity when burning things completely took over as a source of energy. Today, waterwheels connected to generators can produce zero-carbon electricity as they spin.
Notably, an Archimedes screw-style waterwheel was installed along the River Wandle in London in 2012. The 8.5 kilowatt system generates enough electricity to power 18 homes.
While setups like this certainly have limitations, some argue that we are currently under-utilising this age-old form of renewable power. Waterwheels could, in principle, help to decarbonise energy systems, especially for remote communities, and perhaps even go a little way towards enabling grid operators to meet demand at peak times when solar and wind power aren’t available.
A surprise turn
Erhart has never seen the Kashmiri waterwheel in action with his own eyes. It is a particularly dangerous part of the world for foreigners to visit, he stresses. But he was part of a team that built the machine in the city of Pune. They then shipped the wheel to Kashmir for installation. Erhart’s colleagues also supported the deployment of a similar waterwheel in Nepal (pictured at the top of this story), as well as a demonstration prototype in Tegernsee, in southern Germany.
The generating capacity of wheels like this can range from around 300 watts to one kilowatt, according to Erhart, depending on the flow of water. And if there is flooding, it is possible to set up the wheel so that torrents of water can bypass it, meaning electricity generation may continue uninterrupted. Crucially, the design – which is freely available online – is relatively easy to construct and might cost as little as $1,000, Erhart estimates.
Climate change is causing difficulties for people who live in the mountainous regions of Nepal and India. And it is also stressing national electricity grids in those countries. Decentralised microgrids and a mix of renewables including solar and waterwheel devices could, in theory, benefit remote communities by helping them to become energy self-sufficient.
Still, such applications, while potentially impactful, are niche. I wondered whether waterwheels might make a splash in other parts of the world and on a larger scale. Here in my native Northern Ireland a local community group recently restored an historic waterwheel on an old mill building in order to generate electricity.
The Tully Mill Restaurant’s waterwheel, in Co Fermanagh, outputs roughly 1.5 kilowatts, according to Patrick Drumm, group treasurer of the Killesher Community Development Association. Currently, the wheel is hooked up to around 10 powerful outdoor lights at the restaurant, though Drumm adds that the cost of installing the system was significant, coming to around £49,000. The project was made possible thanks to funding from The National Lottery.
Wheels in motion
Someone who argues that we aren’t currently utilising waterwheels enough is Gerald Müller at the University of Southampton. He mentions a handful of companies in Germany that restore or build waterwheels for electricity generation.
“I was talking to the owner of one [of those companies] the other day and he was saying his books are pretty much full for the next three years – interest has increased because of the rise in electricity prices,” says Müller.
He has published research indicating that the efficiency of waterwheels can be as high as 85% or so, in terms of converting water power into electricity. Other studies have also weighed up the potential usefulness of waterwheels in the green energy transition.
One possible downside of waterwheels is the risk they might pose to aquatic life. However, research suggests that waterwheels have a minimal impact on fish, for example.
Müller suggests that, besides supplying private homes and buildings such as restaurants or hotels, waterwheels could also power pumps designed to move water up hills and irrigate fields on mountainsides.
When it comes to restoring traditional waterwheels, each case brings with it unique challenges, which can make projects costly and potentially unattractive. “We’re trying to define more standardised solutions,” says Müller.
Although waterwheels may never supply electricity on a large scale, they may be worth considering in some situations. Aside from anything else, they are arguably the most picturesque and, dare I say it, charming form of renewable energy imaginable.
Further reading on this week’s story
You can access full plans for the waterwheel developed by Erhart and his colleagues online.
The largest electricity-generating waterwheel in Europe is in Dorset, England. Installed last year, the wheel has a diameter of nine metres and outputs 150 kilowatt hours of electricity per day.
Could increased rainfall caused by climate change heighten the output of hydropower systems in the future? In early 2024, hydropower electricity generation in Germany was boosted by increased rainfall.