Solar panels are revolutionizing the future of energy—just look at the solar-powered airplane Solar Impulse—but they have one major drawback. Namely: If it’s raining, they don’t generate nearly as much energy, and they can only store limited amounts of power to get through long stretches of cloud cover. (Sorry England.)
Now, according to Science News Journal, researchers from China believe they have found the solution to the rainy day blues—because they have figured out how to make energy from rain.
Generating energy during rainstorms
According to their paper in Angewandte Chemie International Edition, the answer is graphene. Graphene is a very electrically conductive material, and by adding a layer of electron-rich graphene as thin as a single atom, it allows a massive amount of electrons to flow across the surface.
Rain contains salts that separate into their ionic forms when in solution. (The classic example: NaCl, or table salt, separates into Na+ and Cl- when added to water. However, rain also contains salts with ammonium and calcium as well.) When this rainwater strikes the graphene surface, it clings to the surface, forming a double-layer pseudocapacitor. The energy difference between the layers—the electrons of the graphene and the cations in the water—is so strong, that electricity is generated.
All in all, these solar cells may mean our future may be just a little brighter, even in the rain.
“The new solar cell can be excited by incident light on sunny days and raindrops on rainy days, yielding an optimal solar-to-electric conversion efficiency of 6.53 % under AM 1.5 irradiation and current over microamps as well as a voltage of hundreds of microvolts by simulated raindrops,” wrote the authors in the paper.
Now, 6.53 percent isn’t the best efficiency on Earth—some panels can convert up to 22.5 percent of the energy they receive—but it’s definitely better than nothing.
“All-weather solar cells are promising in solving the energy crisis,” added the authors.
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Image credit: Thinkstock
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