The emergence of "big cell" technology solves one of the key challenges of green energy - the intermittency of wind and solar. Driven by plummeting prices and technological advances that allow batteries to store more and more energy, grid-scale storage systems are seeing record growth in the United States and around the world. Much good has come from the car industry's race to make smaller, cheaper and more powerful lithium-ion batteries for electric cars. In the United States, state-level clean energy bills and tax incentives for storage systems that go with solar installations also play an important role.
California is currently a global leader in balancing the intermittency of renewable energy in the grid with high-capacity batteries. But other parts of the world are fast catching up, with recently announced major battery projects including a 409-megawatt system in South Florida, a 320-megawatt system near London, England, a 200-megawatt system in Lithuania and a 112-megawatt system in Chile.
How quickly large-scale storage develops in the future depends largely on how quickly its costs continue to fall. The price of utility-scale battery storage in the U.S. has fallen dramatically, dropping nearly 70 percent between 2015 and 2018, according to the U.S. Energy Information Administration. Advances in lithium-ion battery chemistry have greatly improved the performance of the batteries, leading to a sharp drop in price. Power capacity is expanding rapidly, and batteries can store and discharge for longer and longer periods of time. Competition and rising battery production have also played a role; Projections from the U.S. National Renewable Energy Laboratory suggest the medium-term cost of lithium-ion batteries will fall another 45 percent between 2018 and 2030.
In California, falling battery prices and the state's aggressive push to move to a carbon-free grid by 2045 have prompted a flurry of energy storage projects. California's 2013 law set a target of putting 1.325 gigawatts of energy storage on the state grid by 2020. According to the California Public Utilities Commission, 1.5 gigawatts of projects have been approved, including 500 megawatts installed so far. While there are no exact figures on the amount of energy storage California will need to achieve its carbon-free goal (the amount depends on future technology mix, energy use and other changes), some analyses estimate that California will need at least 30 gigawatts of utility-scale storage by 2045. A record 1.2GW of storage has been installed in the US so far this year, according to Wood MacKenzie, a consultancy. That figure is expected to rise sharply over the next five years, rising to nearly 7.5GW by 2025.
While Europe leads the way in renewable energy development, it has been slow in energy storage. Energy storage in Europe has been hampered by a restrictive electricity market, with auctions often underestimating the value of storage. However, some large battery projects are now taking shape, including a 320-megawatt system to be built at a new port facility near London.
While energy storage is booming in high-value markets such as California, battery costs need to fall further for large-scale global deployment. In the US, the industry hopes the incoming Biden administration will push for more favourable energy policies, including extending investment tax credits and extending benefits to energy storage systems.