The modern electric grid is getting some help from some admittedly old-fashioned technology.

Flywheels and compressed air don’t sound as sexy as wind turbines and solar cells, but the latter probably won’t go mainstream without the former.

“The growth of renewables has posed a problem,” said Imre Gyuk, program manager for energy storage research at the United States Department of Energy (DOE). “It used to be that the load [demand on the electric grid] was unpredictable, and generation would try to follow it.” As wind and solar installations proliferate, supply also has become unpredictable.

For electric grid operators, “Now it is a balancing act,” Gyuk said during the annual conference of the American Association for the Advancement of Science in Washington, D.C.

Because wind power is generated only when the wind blows, and solar energy isn’t collected on a cloudy day, technologies that can store extra power when it’s not being used and mete it out when needed are becoming increasingly important.

“For this balancing act, storage is ideal,” Gyuk said.

Read the rest at NationalGeographic.com