Using and developing wind and other renewable energy storage technologies raises a host of issues that need to be resolved, including determining who owns the stored capacity and how to finance the costly technology, stakeholders noted during a California Energy Commission workshop October 3. “It is not a technology problem, but a regulatory and business problem,” said Ed Cazalet, head of the Cazalet Group and former California Independent System Operator board member. “There are technologies today that can meet the needs for ramping and storage as a business operation.” However, he added, storage technology is capital intensive and investments are likely only if the developer gets forward long-term contracts with a utility. As the level of renewable power and the push to decrease the carbon content of the state’s energy supplies grow, the importance of storing energy increases. Much of the renewable power supplies--largely wind, as well as solar--are intermittent. For example, solar power production peaks in the Central Valley around 1 p.m. while the area’s demand peaks around 5 p.m. Having existing and emerging storage technologies respond optimally to the grid’s ebb and flow is more challenging, said CEC renewable team lead Gerry Braun, because “the menu of energy storage is very broad and diverse, and attributes quite dissimilar.” Existing storage projects include projects that pump water uphill and release it to provide power at peak periods. However, legal and environmental constraints are increasing on these pumped storage, as well as hydropower, operations because they harm aquatic critters, particularly in the Delta, the heart of the state’s water supply network. Electric vehicles also are potential stores of energy. Utilities are working on bringing to market so-called vehicle-to-grid, or V2G, technologies. Other stakeholders noted that energy storage technologies should be flexible and reliable, as well as properly dispatched to minimize the impacts of clean energy. Another issue is figuring out where to store and interconnect viable storage projects. According to the CEC, improved battery storage devices and new power electronics have revived the storage arena. The CEC Renewable and Public Interest Research Program has worked and invested in storage technology projects, largely wind and some hydro pumped storage and solar projects. Recently funded Energy Commission projects demonstrating storage technologies that offer additional ancillary benefits have advanced the state of the art. Remaining questions stakeholders discussed included not only who owns the stored energy--the developer, utility, or grid operator--but also how to value stored power that is ramped up and down.