As the mix of energy sources feeding power-hungry homes, businesses and industry comes to incorporate more renewables like wind and solar, society faces a reckoning with where to turn when wind and sunshine die down. What will it take for greener sources not only to join fossil fuels on the American power grid, but eventually to displace them?

In February 2019, Los Angeles announced plans to phase out three natural gas power plants by 2029 and to replace them with a combination of renewable energy and battery storage. A few months earlier, the California utility Pacific Gas & Electric won regulatory approval for similar plans. It hoped to replace a trio of natural gas plants with industrial scale battery storage systems, including a 730 megawatt-hour project to be designed and built by electric car company Tesla Motors. For comparison, the two small plants slated for retirement in PG&E’s plan can generate up to 47.6 megawatts of electricity when needed, while a larger natural gas plant in the project can produce up to 606 megawatts.

The idea behind both plans is that the capricious nature of energy from sunshine and wind creates a problem for operators who need to match the amount of energy supply at all times to the amount of demand. Storage technologies including batteries offer a way to maintain the supply-demand balance by drawing electricity from the grid when renewables are abundant and sending it back when demand picks up or renewables’ output falls short.

Read more at Stanford News