California adopts interim rules for battery storage service

In recognition that battery storage service can bestow multiple affirmative benefits upon the electric grid but that its full economic value has not yet been realized, the California Public Utilities Commission (PUC) adopted a series of rules to address multiple-use application issues. In so doing, however, the commission emphasized that the rules are interim and may be refined by an energy storage working group that the commission established in conjunction with the rules. 

The new rules are designed to govern evaluation of energy storage proposals that may be useful for more than one purpose. The standards differentiate storage service by "domain" and distinguish between storage offered for facilitating reliability versus storage provided for a nonreliability purpose. 

A total of 11 rules were approved by the commission, with the belowlisted ones being among the most noteworthy: 

1. Resources interconnected in the customer domain may provide services in any domain; 
2. Resources interconnected in the distribution domain may provide services in all domains except the customer domain, with the possible exception of community storage resources; 
3. Resources interconnected in the transmission domain may provide services in all domains except the customer or distribution domains; 
4. Resources interconnected in any grid domain may provide resource adequacy, transmission, and wholesale market services; 
5. If one of the services provided by a storage resource is a reliability service, then that service must have priority; and 
6. Priority means that a single storage resource must not enter into two or more reliability service obligation(s) such that the performance of one obligation renders the resource from being unable to perform the other obligation(s). 

The commission told the state's three dominant electric utilities — PG&E, SDG&E, and SCE — that they must integrate all 11 rules into their storage procurement applications, service contracts, and evaluation protocols. Re Energy Storage Procurement Framework and Design Program, Decision 18-01-003, Rulemaking 15-03-011, Jan. 11, 2018 (Cal.P.U.C.).