A new battery designed by researchers at Harvard University may open the door to large-scale storage of solar and wind power.

 

The prototype battery stores energy in liquid, organic (carbon-based) molecules, a flexible system that could also significantly bring down power-storage costs. Because solar and wind power are intermittent energy sources, storage solutions are needed to improve their reliability.

 

The device is a flow battery, which holds energy in tanks of liquid chemicals that can be scaled up or down. The actual battery cell, which converts the chemical energy into electricity, is held separately. That means the amount of storage can expand without also increasing the device's wattage capacity.

 

Engineers developed flow batteries decades ago, but they have typically used metals like vanadium, which are expensive in large volumes.

 

With funding from the U.S. Department of Energy, the team at Harvard's School of Engineering and Applied Sciences used computer programs to screen thousands of organic molecules called quinones, which can be found in plants and crude oil. They settled on a quinone similar to one found in rhubarb, and dissolved it in water for the anode side of the battery.

 

"The Achilles heel of this particular battery," team leader Michael Aziz said, is the bromine and hydrobromic acid used on the cathode side. Because these substances are corrosive, they could pose an environmental threat. Aziz said he hopes to find a replacement for bromine in the future.

 

His laboratory is partnering with a company called Sustainable Innovations to demonstrate the organic flow battery on a larger scale within the next few years.

 

"So far, we've seen no sign of degradation after more than 100 cycles, but commercial applications require thousands of cycles," Aziz said.