This Fully Renewable-Powered Island Is Using A Volcanic Crater To Charge Its Batteries

The tiny island of El Hierro is building a Rube Goldberg machine of renewable energy (including a volcano!) to supply energy to its tiny population.

The shift to renewable energy is inevitable, but prying a populace off of fossil fuels often means a long, uphill battle. Not so for the tiny Spanish island of El Hierro, a bit of volcanic rock floating off the coast of the Western Sahara that will become the first island to fully power its 10,000-person population with wind and hydroelectric energy.


Engineers and clean energy types have hailed El Hierro as a rare kind of science experiment. The developer, Gorona del Viento, will launch a wind farm consisting of five turbines in the north of the island this summer. Turbines are tried and true technology when the weather abides, but the novel part of the El Hierro project comes from how wind will join up with a novel energy storage device: A volcanic crater.

Hydraulic turbines capture energy from water that flows from the crater.

When the wind is breezy, turbine electricity will pump water up a 2,300-foot mountainside into a giant crater reservoir. On calmer days, part of that volcanic reservoir will be drained, allowing electricity to be generated from the kinetic energy of water running back down the mountain. In tandem, the two processes work like a renewable Rube Goldberg machine.

Islands have almost been forced to shift to renewables ahead of landlocked nations because of their size, explains Dolf Gielen, director of innovation and technology at the International Renewable Energy Agency.

“Most of these islands are relatively small, so they need power generation technology with that suitable scale. You cannot build a large nuclear or coal plant on an island. So the only viable fossil fuel-based generator tech is diesel, and that’s relatively expensive power,” he says. “A problem on a lot of these islands is that they spent 10% to 20% of their earnings on oil imports.”

Wind turbines sit on hills in northern El Hierro, powering the pumps that draw water from the sea.

El Hierro certainly isn’t the first to attempt an all-renewable future. Gielen’s been working with the remote Tokalau Islands in the Pacific, which are only reachable by two-week boat trip, to generate 90% of their energy from solar panels. The Danish island of Samsø is also one of the longest-running model renewable communities in the world. There, farmers own shares of an offshore wind farm that, with some biofuel in the mix, powers their homes and livelihoods.

“There’s a lot of lessons to be learned in the El Hierro project,” says Søren Hermansen, director of the Samsø Energy Academy. “This is kind of a playground for technology.”

Read more: How Gravity And 100-Year-Old Tech Can Help Solve The Energy Storage Problem

Hermansen points to the importance of having renewable projects that are community-owned and funded. On tourist-friendly El Hierro, the initiative for the new wind farm has largely been driven and paid for by the developers. It’s an open question as to whether that type of set-up can be sustained by the local population.

“In the beginning, I was as arrogant as everyone else. I thought everyone has to be positive and optimistic about [Samsø] project,” Hermansen says of his own experience, before he got the farmers on board. “And I learned that this was only me and my friends from the community that understood the possibility of green innovation. We had to go back and start all over.”

It’s too early to call what the long-term future might hold for El Hierro. But the world will be watching when the island gets its wind farm set up in June.


About the author

Sydney Brownstone is a Seattle-based former staff writer at Co.Exist. She lives in a Brooklyn apartment with windows that don’t quite open, and covers environment, health, and data