Advanced Energy Economy: Cheap Batteries for Backup Renewable Energy | MIT Technology Review

Cheap Batteries for Backup Renewable Energy

A battery made of cheap materials could store power when it’s windy for use when it’s not.

Investors recently chipped in $15 million to fund battery startup EOS Energy Storage, a company that says its batteries could eventually compete with natural-gas power plants to provide power during times of peak demand.

Cheap energy storage is becoming increasingly important as greater numbers of wind turbines and solar panels are added to the grid. If renewable energy is to replace the fossil fuels that dominate power supplies and serve to backup wind turbines and solar panels, very large-scale, inexpensive batteries like the ones EOS is developing will be needed (see “Wind Turbines, Battery Included, Can Keep Power Supplies Stable,” “Battery Could Provide a Cheap Way to Store Solar Power,” and “A Solution to Solar Power Intermittency”).

EOS is trying to commercialize a type of battery that’s based on inexpensive materials: water, zinc, and air (see “Startup Promises a Revolutionary Grid Battery” and “Years in the Making, Promising Rechargeable Metal-Air Batteries Head to Market”). Such batteries—in which zinc reacts with oxygen in air to generate electricity—have been around for a long time, but it’s been difficult to make them rechargeable. Electrodes deteriorate, for example, and the batteries are inherently inefficient because of the difference in voltage levels when charging and discharging them—they waste nearly half the energy it takes to charge them.

EOS has addressed these issues in a couple of ways. It uses a slightly acidic water-based electrolyte that helps prevent deformations of the zinc electrode that can damage the battery.

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