Researchers at MIT have engineered a new kind of rechargeable flow battery that could lead to a greater switch to renewable energy, such as wind and solar. Despite widespread support for renewable electricity, utility planners have hesitated to integrate large amounts of renewables into the electric grid due to the high transmission costs and capricious nature of solar and wind. MIT’s breakthrough membrane-less flow battery, however, could bring us one giant step closer to a greener, more cost-effective electricity grid.
Unlike your thumb-sized household AA battery, flow batteries are industry sized and store their electrolytes in two swimming pool-sized liquid tanks. The aqueous electrolytes are then pumped into a reaction chamber separated by an ion selective membrane and the resulting chemical reaction sparked across the membrane produces free electrons that can be stored or released as energy.
Flow batteries are often cited as the preferred energy storage system for intermittent sources like wind and solar because of their long life span and ability to be idled for long stretches of time without losing their charge.
A main challenge, however, has been cost. The membrane that prevents the electrolytes from causing a chemical short circuit can be prohibitively expensive. In addition, certain chemical reactions can corrode the membrane, necessitating replacement.
In contrast, MIT’s new breakthrough flow battery doesn’t need a membrane, and instead relies on a phenomenon known as laminar flow, where the liquids flow past each other without lateral mixing. The battery would also use a relatively inexpensive and abundant bromine-hydrogen mix to produce energy, bringing costs down even further.
Whereas existing batteries can cost hundreds of dollars per kilowatt-hour of capacity, this breakthrough membrane-less design could produce energy that costs as little as $100 per kilowatt-hour. It’s a target level that the U.S. Department of Energy has estimated would be economically attractive to utility companies, making it a low cost energy storage system that could lead to wider adoption of renewable energy across the grid.