Energy agencies are hearing more requests to determine what will and will not count as a "zero-carbon energy resource" under one of California's most pressing carbon-reduction measures, Senate Bill 100.

Representatives from the California Energy Commission, the California Air Resources Board and the California PUC on Sept. 30 traveled to Fresno to communicate the bill and its requirements, under which electricity providers must supply 100-percent renewable and carbon-free electricity to their California customers by 2046.

The definition of zero-carbon is important to many energy entities in the state, including public utilities such as Turlock Irrigation District. TID receives much of its power from large hydroelectric facilities, including the 203 MW Don Pedro Dam, and whether a large hydroelectric facility like Don Pedro will be considered a zero-carbon resource in SB 100 is still undecided.

"There has been a lot of discussion on what is and is not carbon-free," TID Assistant General Manager Brad Koehn said in a presentation at the Fresno workshop. "Why that matters to Turlock Irrigation is that about 20 to 25 percent of our generation is large hydro at Don Pedro. We feel that that is a purely carbon-free resource and the sooner that it can count towards our long-term, carbon-free output, the better."

The CEC said the definition of a zero-carbon resource will be informed through the SB 100 joint agency report process. Through spring 2020, the CEC, CPUC and CARB will use public and stakeholder feedback from their SB 100 workshops to "inform our report and help to define zero-carbon resources," CEC Deputy Director Siva Gunda told Water Power West.

The Union of Concerned Scientists believes large hydro should count as a zero-carbon resource. UCS Energy Analyst Mark Specht told WPW that large hydro has an important role to play in a zero-carbon grid in California—both in terms of balancing the grid over very short durations and of storing energy over longer durations.

But Specht added that as climate change progresses and impacts California's water cycle, large hydro generation will become more variable, with some very dry years with little energy production and some very wet years with excess production.

"While large hydro should count as a 'zero-carbon' resource, California will need to guard against overreliance on large hydro resources in the face of climate impacts," Specht said.

Sierra Club California Director Kathryn Phillips said it might not matter whether or not large hydro is included in a zero-carbon definition.

"I don't know if not including [large hydro] in the definition will change one thing or another," Phillips said. "We as an organization don't like the impact dams have. You want zero-carbon, but you don't want zero-carbon that creates a whole other realm of negative environmental impacts."

California's renewables portfolio standard program does not currently count large hydro as an eligible renewable energy resource. UCS said it believes the RPS should continue to exclude large hydro in order to promote other renewable energy sources, such as wind and solar.

In 2018, California used about 26,300 GWh of hydroelectric power, which was about 13.5 percent of the state's total system power, according to the CEC. There are 270 hydroelectric facilities in the state with a total capacity of about 14,000 MW.

CEC representatives at a previous meeting in August said they are looking at expanding the potential meaning of zero-carbon.

"When you look at [SB 100's] language, really the intent is to allow for as many potential avenues as possible while still meeting the intent of the bill," CEC project manager Terra Weeks said at an Aug. 14 CEC meeting. "We're looking more at the attributes of technologies versus a prescriptive list of technologies."

And former state Sen. Kevin de León, who sponsored SB 100, said last year in a letter that the "zero-carbon portion of SB 100 is intended to be more inclusive than the RPS portion in terms of the types or resources that are eligible . . . If an energy generation resource does not produce greenhouse gas emissions, it would be eligible to meet the 100 percent renewable and zero-carbon target."

Investor-owned utilities are also pushing to quickly define zero-carbon. San Diego Gas & Electric is advocating for a cost analysis to evaluate the reliability and financial impact of different renewable and potentially zero-carbon resources.

In a letter to the joint agencies, SDG&E Manager Tim Carmichael said a cost analysis could provide "clear direction to the market, including a consensus definition of 'zero-carbon' and the way in which the 100 percent renewable and zero-carbon electricity goal will be measured (e.g., hourly or annually)."

"Considering the timing of the initial report (2021), and subsequent reports (every four years thereafter), waiting until the mid-2020s to provide clear, analysis-based direction is impractical and could undermine the goals of SB 100," Carmichael said in the letter.

Other stakeholders in SB 100 recently said the state's energy agencies should focus on land-use planning first and foremost in order to secure the clean electricity future mandated by SB 100.

Defenders of Wildlife said achieving the goals of SB 100 is not just a matter of identifying how much and what kind of generation needs to be developed and procured, but also of understanding potentially significant land-use ramifications of those development projects.

"Energy planning is land-use planning," Defenders of Wildlife Program Director Kim Delfino said in a letter this month to the CEC. "Achieving 100 percent renewable electricity could require up to 1.2 million acres of development in California. Such a massive amount of development would a be sweeping change to the landscape and natural resources in California or the West."

Delfino recommended that agencies focus electricity generation and transmission development in areas with the least amount of potential for land-use conflict, and should promote distributed generation near loads.

The agencies must submit a finalized joint report on the status of SB 100 to the state Legislature by January 2021

Staff Writer

David Krause is an energy reporter covering the California Energy Commission and Air Resources Board. He writes about transportation, climate change, utilities, and wildfires. He has an MFA in Writing, an MA in English, and a BS in Civil Engineering.