Batteries could reduce reliance on fossil-fuel-powered peaker plants, which kick in when high energy demand puts the grid under strain, said Dvorkin. In New York, for example, they may come online on sweltering summer days where residents blast their air conditioners. Under state environmental regulations, these peaker plants are set to be phased out, but the New York Independent System Operator, the non-profit that manages the state’s grid, has continually extended their use, citing risks of outages.