“What people really miss about electricity storage is it’s not just a daily storage problem. Wind and solar availability around the world, from week to week and month to month, can vary up to a factor of five or six.”

—- Armond Cohen, executive director of the Clean Air Task Force, a group that researches low-carbon energy  technologies; quoted in Julian Spector, The Environmentalist Case Against 100% Renewable Energy Plans, CITYLAB, July 20, 2015