The growth of renewable energy, such as solar and wind, cannot advance very far without development of better technologies to store electrical energy, as well as deployment of a more advanced electricity grid, says a report released by the American Physical Society last week. The report supports state and national efforts to spur renewable energy through standards that call for about 20% of electricity to come from renewable sources by 2020. Although these energy sources have great potential, their drawbacks include natural variability in wind and sun and the fact that renewable-energy installations are often located far from urban and industrial areas that use great amounts of electricity. The study urges the Department of Energy to emphasize programs to support batteries and an expanded electricity grid. It particularly encourages efforts to develop stationary storage devices, especially batteries, and urges DOE to restart R&D for stationary battery programs that were the focus of R&D in the 1980s and ’90s but that were shifted to develop batteries for electric vehicles.