Rust Offers a Cheap Way to Store Wind, Sun Power

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Consider a wind farm generating electricity at two in the morning. Because most people are asleep, there’s little demand for electricity on the grid, so energy produced could become a surplus with little to no value. Storing this excess energy in some kind of battery is a way to conserve the renewable energy for use during peak times, but methods for doing so are cumbersome and expensive.

But now researchers have developed a more affordable and efficient way for energy companies and homeowners to store and reuse wind and solar power. Curtis Berlinguette and Simon Trudel, two chemistry professors from the University of Calgary report a breakthrough that makes it possible to store renewable energy in battery-like devices known as hydrogen fuel cells, which have an energy density over 150 times higher than a lithium-ion battery.

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The technology represents a major step forward in creating a large-scale, clean energy economy.

"The economy of alternative energy conversion really does come down to price," Daniel Gamelin, a Washington University chemistry professor, told Discovery News. Gameline, who also works on energy conversion technologies for renewable energy, calls Berlinguette's and Trudel's work a promising breakthrough for cost reduction in this field.

The breakthrough centers around a device known as an electrolyzer, which stores energy as hydrogen. Berlinguette, who's also director of the university's Center for Advanced Solar Materials, says to think of an electrolyzer as a box that has two lines going in and two lines coming out. "Going in, you have electricity and water. Coming out, you have hydrogen and oxygen fuels," he said.

The electric charge going in comes from all of that excess electricity being produced by wind turbines or solar panels. Catalysts inside the device use those electrons to split water molecules into hydrogen and oxygen. That hydrogen can then be stored as energy in fuel cells for as long as needed and repurposed later as electricity.

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"When you need that electricity back, you just convert that hydrogen by mixing it up with the oxygen that was generated in the fuel cell and regenerate electrons," said Berlinguette.

Berlinguette's technique has to do with those catalysts. Normally they're made from rare, expensive or toxic metals such as ruthenium and iridium. Berlinguette and Trudel, on the other hand, have produced catalysts from abundant, non-toxic metals such as iron, cobalt and nickel.

“We’re effectively just taking a nanoparticulate form of rust and binding it with other cheap metals,” Berlinguette said.

With this combination of cheap metals, the team's catalysts not only performed as well or better than expensive ones on the market, they were significantly cheaper. For comparison, ruthenium and iridium typically cost $5.37 and $18.45, respectively. Berlinguette and Trudel’s iron-based catalysts cost $0.03.

For now, the economics of electrolyzers tend favor large, commercial systems. At this scale, cutting costs even at the level of catalysts could translate into thousands of dollars of savings.

And with the ability to store large amounts of electricity, an energy company could purchase electricity generated at night for a huge discount and sell it the next day during peak times for a premium.

Berlinguette and Trudel have patented their technology and created the FireWater Fuel Corp., to commercialize their catalysts. A study detailing their technique was published this week in Science.