Looking to avoid power blackouts, California may turn to the one energy source it’s otherwise desperate to get rid of: fossil fuels.

A sweeping energy proposal Gov. Gavin Newsom signed Thursday puts the state in the business of buying power to ensure there’s enough to go around during heat waves that strain the grid. But some critics say the method of getting there is at odds with the state’s broader climate goals, because it paves the way for the state to tap aging gas-fired power plants and add backup generators fueled by diesel.