One of the greatest technical problems facing the development of renewable sources is storing the collected energy for later use. If your home or business is solar-powered, come the evening you have to buy electricity or use very expensive batteries to keep the lights on. Utilities with large-scale solar and wind farms have the same problem managing these intermittent power sources. And much of the power from the always-on nuclear and coal plants goes to waste at night because demand is low and it’s too expensive to store the energy.
Michael Aziz and his research team at Harvard’s School of Engineering and Applied Sciences have developed what’s called an organic mega-flow battery, which has the potential to solve this problem.
The organic mega flow battery has two components: the energy source ("organic" substances) and the storage system (a "flow" battery.)
“The flow battery is different from a traditional solid electrode battery,” Aziz explains, “because it stores the energy outside the battery container itself in storage tanks full of fluids. When you want electricity, you flow [the fluids] into the cell past the electrodes, where they’re converted ... and they give off the energy in the form of electricity.”
One nice thing about a flow battery is that it can potentially be any size. The energy is stored in tanks separate from where the electrodes come together, so the amount of energy storage is limited only by the size of the tanks. "That’s potentially a much cheaper way of storing large amounts of energy than stacking up entire banks of solid electrode batteries," says Aziz.
Now, the most commercially-advanced flow battery stores energy using Vanadium, a rare and expensive metal. Aziz’s team has replaced this metal with a class of organic molecules called quinones. “There’s a quinone in rhubarb,” Aziz explains, “that is so, so close to the molecules that we actually have ... that some people are calling [our battery] a rhubarb battery.”
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