In October 2015 a ruptured well in a natural gas storage facility in Aliso Canyon north of Los Angeles leaked 97,100 tonnes of methane into the atmosphere — making it one of the worst environmental disasters in the US since the Deepwater Horizon oil spill five years earlier. Thousands of people were displaced.

The following year utility Southern California Edison decided to invest in batteries to reduce the region’s reliance on gas for electricity — a contract that was won by Tesla. It was a turning point for electric utilities, which have relied on natural gas plants to provide power for over half a century.

Their greater use of batteries by utilities could help grids better integrate renewable sources of energy that are often intermittent. This in turn would help make electric cars truly green, by reducing their reliance on electricity supplied over the grid that is still often generated from fossil fuels.

Utilities have started to invest in ever larger battery projects over the past two years. Last year Tesla installed a 129 megawatt hours battery in South Australia, to store wind energy from the Hornsdale wind farm. Drax Power in the UK said in September it wanted to build 200 MW of battery storage at its power station in Yorkshire. Financial Times

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