Implementing the state\u2019s one-third renewable energy standard is a major challenge for the California Public Utilities Commission. \u201cIt\u2019s very prescriptive,\u201d Julie Fitch, CPUC energy division director, said May 16. Commission staff is grappling with how \u201cto make rules clear and not interfere with renewable procurement,\u201d she added at the Power Association of Northern California conference. The law is considered more complex and mandate-bound than the state\u2019s former 20 percent Renewables Procurement Standard. According to Fitch, the CPUC issued 44 decisions to get the lower renewable requirement off the ground, which ranged from setting ground rules for tradable renewable energy credits to making way for \u201cflexible compliance.\u201d Although the 20 percent renewables portfolio standard law required investor-owned utilities to meet the mandate by 2010, the CPUC allowed contracts, and not online supplies, to count until 2013. Among the many unresolved issues going forward with the higher standard are whether regulators should set additional annual renewable targets, what contracts can be \u201cbanked,\u201d and what the level and timing is for the CPUC\u2019s supply price cap. \u201cNo one has done this before,\u201d said Fong Wan, Pacific Gas & Electric, senior vice president of renewable procurement. The 33 percent renewables mandate requires that private and public utility portfolios be made up of 20 percent alternative supplies by 2013. The only other deadlines are the end of 2016 when power portfolios are to reach 25 percent and 2020 when 33 percent is expected. Fitch said setting annual or other targets may be considered. The new law limits carrying forward excess renewable supplies (that is, \u201cbanking\u201d) to contracts that are 10 years or longer. To be determined is what qualifies as the start of a contract--when it is on line or before that time. The higher standard also involves ongoing debate over how to accommodate the ebb and flow of solar, wind, and other non-fossil supplies. Among the key questions are how much fossil power generation is needed to back up supply gaps and the amount of energy storage in play and associated costs. How much independent generators are to be paid to provide back up power remains controversial. They are paid for energy supplies, but efforts to create a capacity market as another revenue stream for power producers in California failed. According to Jan Smutny-Jones, Independent Energy Producers executive director, the current payment structure between utilities and merchant generators does not allow the latter to make a profit. Smutny-Jones added that anything resembling an alternative payment strategy like a capacity market would be relabeled. \u201cWe\u2019ll call it Ted, or something else.\u201d Wan said he was not willing to pay generators of aging, inefficient gas power plants the same capacity price he pays those that own modern facilities.