How Croissants Could Help Solve One of Solar Power's Biggest Problems

Inspired by the flaky pastry, scientists invented a new device for storing renewable energy.
croissants renewable energy polymer film capacitor

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Scientists, inspired by croissants, just invented a device that could deliver solar-powered energy even when the sun isn’t shining.

Unlike coal and nuclear power, wind and solar can’t be turned turned on or off. That makes storing their energy and releasing it later, when it’s cloudy and the wind isn’t blowing, one of the biggest challenges for renewable energy.


Current devices, like capacitors and batteries, have their limitations, but a team of scientists at Queen Mary University of London just created a more efficient storage method. The little gizmo, based on the flaky French pastry, can hold 30 times more energy than any other device of its kind on the market right now — and it won’t be any more expensive to produce.

“The biggest problem with making the grid run on renewable energy sources has got to be energy storage systems,” said Ramamoorthy Ramesh, a professor of physics and materials science and engineering at the University of California, Berkeley, who was not involved with the study. “One way to do this is to have these capacitors … which can store large amounts of energy and discharge that energy very quickly.”

The scientists invented a modification to a gadget called a polymer film capacitor, which can store energy and release it rapidly. Film capacitors, components found in almost every electronic device, use very thin layers of material as electrical insulation. The scientists figured out that by folding a capacitor over itself the way bakers do with dough to make pastries buttery and delicious, they can make the device more dense and store more energy in a smaller space.

The findings, published Friday in Nature Communications, could help the grid run on greener, more variable sources of energy like wind and solar.

“You’ve probably never made a croissant,” Emiliano Bilotti, an author of the study and a materials engineer at Queen Mary University in London, told VICE News (correctly). “You should try, because it’s actually quite simple. You put a layer of butter on a layer of dough, you squeeze the two layers together, and you fold it again.”


Huge batteries may ultimately be the key to making the grid run well on renewable energy, but capacitors play a role too. While batteries charge and release power slowly, capacitors do the opposite: They charge and release electricity fast. Depending on energy demand, the grid might release energy from either a battery or a capacitor to help you, say, power your microwave.

“It’s about finding a cheap way to store more energy,” Bilotti said. “Other methods have been extremely expensive and technical. The novelty of this capacitor is that we’ve managed to modify commercially available materials to make them more effective.”

The croissant-like capacitor could also improve other types of technology that people use all the time, not just renewables. The device might have applications in electric cars and wearable tech — in short, anything that needs to store energy in a minute package and release it quickly.

That said, this invention isn’t a silver bullet. It’s likely only a component of helping the grid run on renewable energy.

“In a broader context, this isn’t an Iron Man or Captain America–level invention,” Ramesh said. “It’s one of the supporting characters.”

Cover image: Fresh croissants on the market in Palma, April 13, 2019 (Winfried Rothermel/picture-alliance/dpa/AP Images)