A palm-sized experimental flow battery developed by Massachusetts Institute of Technology researchers has the potential to solve intermittency challenges in utility-scale renewable energy systems.
The MIT team has engineered a prototype flow battery storage system without the expensive membrane usually required.
The device works by a process called laminar flow, whereby hydrogen fuel and a liquid bromine solution are flowed past two electrodes, creating energy. But the reaction causes the solutions to combine, creating an acid that corrodes the costly membrane, degrading its storage capacity.
By removing the membrane and directing a current of hydrogen gas over the electrodes, Martin Bazant, professor of chemical engineering at MIT, along with colleagues William Braff and Cullen Buie, found the solutions streamed through in parallel, with very little mixing.
They also discovered their battery produced a maximum power density of 0.795 watts of stored energy per square centimetre – three times as much power per square centimetre as other membraneless systems.
“This technology has as much promise as anything else being explored for storage, if not more,” says Buie. “Contrary to previous opinions that membraneless systems are purely academic, this system could potentially have a large practical impact.”
As the set-up costs of utility-scale renewables such as wind and solar power systems falls to record lows, finding ways to provide cheap and reliable energy storage to cover intermittency issues is becoming a boom market.
“Energy storage is the key enabling technology for renewables,”” Buie says. “Until you can make [energy storage] reliable and affordable, it doesn’t matter how cheap and efficient you can make wind and solar, because our grid can’t handle the intermittency of those renewable technologies.”
Bazant and his team have created a design tool that will enable them to scale up their palm-sized prototype, which he says will allow them to break records of power density with more engineering guided by the model.
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