Energy Electricty Storage (EES) is likely to become more and more important as intermittent solar and wind energy resources penetrate the grid.   EES may be a very useful and perhaps essential way to manage the variability of intermittent renewable energy resources to allow developers to continue building wind and solar projects at an accelerating pace.

On July 9, 2010, the Policy and Planning Division of the California Public Utility Commission (CPUC) issued an interesting Staff White Paper entitled "Electric Energy Storage: An Assessment of Potential Barriers and Opportunities." The report is worth reading for those who are interested in the future of renewable energy and the roll that EES can play in enhancing the deployment of intermittent renewables.

The report describes "a promising new set of Electric Energy Storage ("EES") technologies [that] appear to provide an effective means for addressing the growing problems of reliance on an increasing percentage of intermittent renewable generation resources."  The report observes that EES can provide several basice services, such as (1) supplying peak electricity demand by using electricity generated during periods of lower demand (e.g., storage of wind energy generated at night for use during daily peak periods), (2) balancing electricity supply and demand fluctuations over a period of minutes, and (3) deferring expansion of electric grid capacity (including generation, transmission and distribution). 

Potential storage technologies include pumped hydro, compressed air energy storage ("CAES"), batteries, thermal storage (e.g., solar thermal plants), flywheels, unltracapacitors and superconducting magnetic storage–the report provides short but helpful description of each technology.  Storage presents interesting legal and policy issues, because "[r]egulators are uncertain how EES technologies should fit into the electric system, in part because EES services provide multiple services such as generation, transmission and distribution."  In addition, "regulators do not yet know how EES costs and benefits should be allocated among these three main elements of the electric system." 

The report makes a number of recommendations, including that the CPUC should conduct a rulemaking to develop policies to remove barriers to the deployment of EES technology in California.  The report also proposes that the CPUC consider placing EES within California’s energy resources loading order, require utilities to incoporate EES into their integrated resource planning processes, encourage CAISO to change ancillary service market rules to allow EES systems to more easily bid into regulation markets, and integrate EES into utility transmission planning.

The report concludes that "the major barrier for deployment of new storage facilities is not necessarily the technology, but the absence of appropriate regulations and market mechanisms that properly recognize the value of the storage resource and financially comepnsate the owners/operators for the services and benefits they provide."

You can find the report here.