The smart grid is the modernized version of the electrical grid that will be built over the next decade or two. The goals of the smart grid are higher efficiency, lower pollution, and lower cost. The traditional grid stores almost no energy: electric supply from power plants must track user demand within seconds or minutes. When demand rises suddenly, so-called peaking turbines, fired by natural gas, must rapidly come on-line. Since such plants are idle most of the time, they are an expensive source of power. With storage units scattered at strategic points throughout a smart grid, however, shifts in demand could be met more flexibly, lowering transmission and generation costs. For example, fewer peaking turbines would be needed.
Energy storage will also enable the grid to support greater integration of renewable energy sources. For example, wind turbines generate electricity only when the wind is blowing and solar panels only generate electricity when the sun is shining. At present, the grid is able to accommodate only a certain amount of power from such sources, but with affordable storage, the grid will become more flexible and renewable generators will able to produce energy more steadily. However, no low-cost technology for utility-scale energy storage is yet on the market.