Due to the abundance of shale gas, electric utilities are shifting from coal to natural gas, which improves air quality and reduces greenhouse-gas emissions. Counterintuitively, the Sierra Club has taken legal action to block LNG exports from Cove Point. Ostensibly, the environmental group opposes increased shale-gas production because renewable energy sources like solar and wind will be unable to compete economically with natural gas. But renewable energy sources are intermittent. Solar photovoltaics and wind turbines only produce electricity when the sun is shining and the wind is blowing. Natural gas electrical generation plants can operate continually, regardless of weather conditions.