Scientis Have Developed Solar Cells That Generate Electricity From Raindrops
Here in the 21st century, solar power is an indisputable energy contender. It’s the far-flung year of 2016 and already solar is cheaper than conventional energy in 42 U.S. cities. The solar industry is booming, generating ever more jobs, and small-scale and community solar projects are markedly on the rise. Deutsche Bank has projected that solar will be the dominant source of energy on the planet in less than 15 years, and when its environmental benefits are compounded with its utility savings, there seems to be nothing stopping this renewable dynamo from obscuring the dirty fossil fuels of the past. Unless it rains.
Solar power has one major strike against its clean credentials: Without sunlight, it generates very little electricity. That’s an insignificant problem in sunny states like California, but California is an exception (we haven’t had a decent rain in half a decade, but that’s another matter entirely). For most states in the U.S., cloudy days (like seasons) are part of the natural cycle of weather, and every cloud that passes over a solar panel reduces its advantage over oil and gas and coal. But that disadvantage, like a passing cloud, can’t last forever.
Scientists from the Ocean University of China and Yunnan Normal University have developed an experimental solar cell that generates electricity from raindrops.
Researchers coated a dye-sensitized solar cell (an inexpensive, thin-film cell) with a one-atom-thick layer of graphene. When a salt-rich solution similar to rain is applied to the cell, the graphene functions as a pseudocapacitor, separating out the positive and negative ions in the solution. The graphene layer has a negative charge, which interacts with the positive ions in the salty solution (such as sodium, calcium and ammonium). The difference in these charges is enough to produce voltage and a current.
These graphene-coated cells yield a solar-to-electric conversion of 6.53 percent under AM 1.5 irradiation and generate hundreds of microvolts from simulated raindrops. The experiment, published in the journal Angewandte Chemie, is still in the “proof of concept” phase and has yet to be tested with real raindrops, which boast a variety of ions and often in lower concentrations. Still, this research shows promise for a future in which “all-weather” solar panels become the norm, conquering the intermittency problem and making solar power a viable energy source in a variety of climates and conditions.