Increases in battery storage capacity will soon transform renewable energy. Battery manufacturing is expected to more than double by 2021, with China leading the charge in building new factories. US states, meanwhile, are already investing in battery storage to support the growth of wind and solar power. This battery boom will help utility-scale energy and individual consumers: a new study finds that batteries could allow solar households to start “defecting” from the power grid in a little over a decade. Just one question remains: where are we going to get the lithium for all of these batteries?