Multiple technologies are vying to house temporary surpluses of solar and wind power.
A mind-boggling array of energy storage technologies—including batteries the size of an Ikea furniture store and tanks of salt hydrates the size of oil drums that release heat—is being tested in labs and workshops across the globe.
They are vying to become the approach of choice to stabilize electric grids when energy from renewable sources passes 20% on an individual grid—the point at which the unpredictable nature of renewables becomes unmanageable. In a future where solar and wind energy steadily replace carbon-based fossil fuels, energy storage technologies will be needed to keep the lights on when the wind drops and the sun goes down.
Energy storage used to be so simple. It was once a low-tech sector in which water was pumped uphill during low energy demand and released during peak demand to drive turbines and return electricity to a grid. But pumped hydroelectric storage is limited by geography.
The new technologies include chemical, electrochemical, mechanical, and thermal energy storage systems. Each type presents different capacities, charge-discharge rates, reliability, and capital and operating costs, which means many could find market niches in the coming years.
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The energy storage market is taking off now because wind and solar have finally become cheaper sources of electricity than burning coal and are on par with or cheaper than natural gas. “These prices are beating everyone’s expectations,” says Rory McCarthy, senior analyst for energy storage with the consulting firm Wood Mackenzie.