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Energy storage will play a critical role in a grid that’s increasingly filled with solar and wind electricity. Pacific Gas & Electric just completed what it says is the largest energy storage project in California and is marking that occasion in a ribbon-cutting ceremony today.
The 4MW project, located in San Jose, is made up of sodium sulfur batteries that can store over 6 hours of energy. The utility plans to use the system to figure out how energy storage could help it manage the growing amount of renewable energy that it must supply to its customers. California requires its utilities to get 33 percent of their power from renewable sources by 2020.
That requirement has prompted utilities to scramble and sign contracts to buy lots of wind, solar and geothermal energy from independent power producers. We are starting to see some of the large solar farms being built and coming online.
The requirement also is raising concerns about the stability of the grid, which works best when there is a balance of supply and demand. Solar and wind farms can’t produce power around the clock, and the amount of energy produced also depends heavily on the weather. That has elevated the importance of using energy storage to bank some of the solar and wind energy produced and release it at whatever volume or pace that is necessary to help maintain that balance of supply and demand.
Another reason for using storage is to store electricity when demand is low, such is at night when wind can kick up, and use that electricity during the middle of the day when homes and offices crank up their air conditioners.
Back in 2010, California lawmakers flirted with the idea of requiring utilities to use storage. But they ended up passing a bill that didn’t do that but instead directed the Public Utilities Commission to study the necessity of energy storage and determine if it should create a mandate for it.
Even if there isn’t a regulatory mandate, power producers and utilities still have to investigate the use of energy storage, only because it’s a viable way to give them more flexibility in managing renewable energy. What they are struggling with is to figure out which technology works the best. The best storage should be able to store lots of energy in a small space, easy to control and monitor its charging and discharging and cheap. Utilities and power producers will have to define what those criteria means for them. Those decisions are difficult to make at this point because energy storage that is designed for grid management is uncommon. It’s only in recent years when we started to see more companies — established battery makers and startups — engineering energy storage equipment and software for the grid.
PG&E opted for sodium sulfur batteries and won a $3.3 million grant from the California Energy Commission to carry out the project. The project is designed to run for three years, though the battery system should last at least 15, according to a PG&E blog post in 2010. NGK Insulators supplied the batteries while S&C Electric served as the project’s general contractor.
Other California utilities also are looking at what batteries can do for their power grids. Southern California Edison, for example, plans to install an 8MW lithium-ion battery system in an area with many win farms.
Some solar companies that sell equipment or install solar panels for home and business owners also are offering or plan to sell batteries. SunPower recently talked about potentially sell lithium-ion batteries while SolarCity is already bundling batteries from Tesla Motors with solar panels.