Self-charging electric cars are just a dream, right? Maybe not. A team of researchers at Case Western Reserve University think they may have found a way to recharge the battery of an electric car using solar cells. And no, they are not considering a car that has a billboard-sized array of solar panels bolted to the roof. They are are talking about flexible cells that could be integrated seamlessly into the exterior surfaces of ordinary cars, according to a report in Gizmag.
Electric Cars Need Electricity
Electric cars need electricity. Duh. Up to now, most of that electricity has come from the electrical grid. That’s a potential problem, because as much as electric car makers want to say their cars are good for the environment, the truth is, 32% of electricity in the US still comes from burning coal. (For the purposes of this discussion, I am including plug-in hybrids in the category of electric cars. Purists may quibble, but plug-in hybrids are going to rule the marketplace for the next several years, so get used to, get over it, and move on.)
Lots of people have clever ideas for how to recapture some of the kinetic energy of a moving vehicle and feed it back to the battery to help extend driving range. Most electric cars have regenerative braking systems. When you take your foot off the throttle, the electric motor that helps move the car forward becomes a generator that puts electricity back into the battery. The new Chevy Volt has a paddle on the left side of the steering column that lets the driver control how much regenerative braking is used.
Goodyear says it can make tires that create a small flow of electrons from the flexing of the tread while driving. Others think they can do the same thing by harnessing the power of our shock absorbers as they move up and down in response to bumps in the road. Researchers at the University of Manchester say they can use graphene to make electricity from waste engine heat.
All those ideas taken together may make a significant difference in how far we can drive our electric cars before we have to plug in the charging cable. Lots of folks like the idea of using sunlight to recharge our electric car batteries, though. That’s the plan for the Immortus electric sports car from Australia, for example.
New Research on Perkovsite Solar Cells
What the people at Case Western have done is take the idea of solar cells on cars and raised the game to a new level. They wired four perovskite solar cells in series to directly charge lithium batteries. The array has an efficiency of 7.8%, which they believe to be the most efficient configuration for automotive use reported to date.
“We found the right match between the solar cell and battery. Others have used polymer solar cells to charge lithium batteries, but not with this efficiency,” said Liming Dai, the leader of the research team. He added that the coupling appears to have outperformed all other reported pairings of photo-charging components and compatible batteries or supercapacitors.
Solar cells made of perovskite react to a broader range of the visible light spectrum than ordinary cells made from silicon. Perovskite’s potential for highly efficient power conversion and a quick payback in terms of energy savings over conventional power sources have made it one of the fastest growing sectors in the solar power field.
“We envision, in the not too distant future, this is a system that you could have at home to refuel your car and, eventually, because perovskite solar cells can be made as a flexible film, they would be on the car itself,” said contributing author Jiantie Xu. The research was published recently in the scientific journal Nature Communications, but reading about it here is a lot more fun. Trust me on this.
Self-charging electric cars that run (at least partially) on sunlight? In the immortal words of President George W. Bush, “Bring it ON!” Chest bump optional.