The California Independent System Operator is taking comments through Aug. 13 on a hybrid resource market initiative aimed at dealing with multiple technologies from a single resource.

The grid operator released an issue paper on the topic and seeks feedback on hybrid resources and their deliverability,

Hybrid generation resources continue growing, according to the grid operator, which defines them as “a combination of multiple technologies or fuel sources combined into a single resource with a single point of interconnection.” This has traditionally included energy storage, but it does not have to, according to CAISO.

Forty-one percent of the total capacity currently seeking an interconnection to the CAISO system is considered hybrid. The ISO notes that not all the capacity in the queue will reach commercial operation, but adds that the number of such hybrid projects will grow significantly.

The initiative seeks to ensure hybrid generation sources are reliably and efficiently integrated into the grid while addressing technical questions such as configurations, metering and market participation, as well as new operational and forecasting challenges these technologies present.

“Key to the initiative is determining whether a framework should be developed for resources intending to participate in the market under a single resource ID,” Sarah E. Kozal, an associate with Stoel Rives’ energy development group, said in a legal update published Aug. 6. “Though the CAISO expressed a strong preference for hybrid resources utilizing multiple resource IDs, some developers prefer a single one—in part due to [investment tax credit] eligibility uncertainty.”

Another issue that will need to be addressed is data gathering. Because it is a Western Electricity Coordinating Council-qualified reporting entity, CAISO has to submit meter data for renewables, but new metering requirements might be needed for it to meet various entities’ reporting specifications. These may also be needed for state renewables portfolio standard reporting requirements.

Load-serving entities continue combing the CAISO report to determine how these issues might affect operations and/or projects.

“We’re interested in it in particular because of the airport microgrid we’re developing with the Schatz Research Energy Center,” Richard Engel, director of power resources for Redwood Coast Energy Authority, said (see CEM No. 1535 [15]). “It came onto our radar recently because we’re trying to figure out how to interface with CAISO and what our configuration and best market options are.”

The airport microgrid system—the design of which features a DC-coupled storage-plus-solar system—uses two intermingled resources, which is new to CAISO, Engel said. RCEA is working with the grid operator to determine how to optimally configure the system “to capture the values of all of the [renewable-energy credits] from solar” as well as whether the battery system can be charged as needed from the grid, among other issues.

“We are still getting up to speed on what our market-participation options are,” Engel said. The Humboldt County-based joint-powers agency intends to participate in the hybrid resource market initiative, but with the help of the California Community Choice Association. “We are letting them be our comment filer,” he said.

Because the initiative is still in its early stages, “it is difficult to determine if there are concerns with the ability of this initiative to support both reliability and California environmental policy goals as an integrated pair,” Robert Laffoon-Villegas, a spokesman for Southern California Edison, said. “SCE will participate throughout the stakeholder process to evaluate exactly this, as well as to ensure that our customers are being served reliably, safely, environmentally consciously, and in an affordable manner.”

SCE is preparing comments on the issue paper and plans to file them by the deadline, Laffoon-Villegas said.

San Diego Gas & Electric “supports the CAISO evaluating issues related to hybrid resources because they are becoming more prominent in CAISO’s interconnection queue,” utility spokesperson Robert Iezza said. “The main concern for SDG&E is making sure that all the market rules are appropriate for hybrid resources. SDG&E looks forward to working with CAISO and other stakeholders to develop solutions that will maximize the benefits of hybrid generation resources.”

Once comments are reviewed, a straw proposal is tentatively scheduled for release in September.

The draft final proposal is scheduled to be released in April 2020, with approval by the CAISO Board of Governors expected at a later date.