Giant batteries deliver renewable energy on demand

Solar energy is plentiful – when the sun is shining. The force of the wind is constant – when the wind blows. However, ensuring a constant supply of electricity from intermittent energy sources is a challenge. NASA focused on this problem more than 45 years ago when the agency designed a new type of liquid battery during the energy price shocks of the 1970s. While engineers continued to work on flow batteries, as they are now called, over the following decades, the technology has gained even more attention in recent years. greater interest due to the urgent need for climate change, which is forcing a greater scale towards renewable energy sources such as solar and wind energy.

It’s safe to say that today’s flow batteries owe something to the significant advances that occurred in technology in the 1970s, when a NASA engineering team of chemists, electricians, and mechanics developed the chromium gel flow battery at the Lewis Research Center – now Glenn Research Center – in Cleveland.

The NASA system consisted of two tanks of liquid electrolyte solutions, one saturated with iron chloride and the other with chromium chloride. These electrolytes were pumped through the battery cell, triggering a chemical reaction via a membrane that separated the two solutions inside the battery. During charging, electrical energy was converted into chemical energy and stored in the liquid electrolyte. To discharge the energy, the process was reversed.

ESS Inc. based in Wilsonville, Oregon, built on early NASA work by developing its own flow batteries using only iron, salt and water. When the ESS team began developing the battery in 2011, the company’s founders wanted to use iron, as NASA did. They found that they could combine iron with a simple salt solution that was cheaper to obtain and easier to work with than the chromium mixture that NASA was using.

ESS flow batteries are designed for power grids that are increasingly powered by intermittent wind and solar energy generation. The company’s systems store up to 12 hours of energy and are used to provide emergency power to critical public facilities.