FERC in January directed RTOs and ISOs to boost the participation of hybrid resources by modifying market rules to accommodate growing renewable energy projects with energy storage. The directive, however, did not mandate any rule changes. FERC did ask that RTOs submit reports that address four hybrid resource issues: terminology, interconnection processes, market participation and capacity valuation.
On Wednesday, the Northeast Energy and Commerce Association hosted a webinar on hybrid resources as part of its series on the role of energy storage in decarbonization. Renewables paired with storage seeking interconnection demonstrate a significant shift in the resources that will decarbonize the grid. Whether for renewables or conventional plants, additional storage brings needed flexibility and reliability to the low-carbon grid of the future, speakers said.
Mark Ahlstrom, vice president of renewable energy policy at NextEra Energy Resources, admitted “that not too many years ago … I thought that it would be really silly to couple storage with any renewable.” He said he has had to “eat those words.”
Ahlstrom said that when combining two resources like solar PV with battery storage, “throwing away all that clipped energy” is no longer an issue, as it is stored in the battery for future use or to provide ancillary services.
California-based Wellhead Power Solutions began developing a thermal-battery hybrid in 2013 to help maintain reliability in CAISO during large-scale deployment of renewable energy resources. Wellhead eventually patented the technology and partnered with General Electric to sell the hybrid-electric gas turbine (EGT). In the last five years, Wellhead has installed five of these thermal hybrid EGT “systems” in California and Canada.
“We saw some of the advantages that energy storage had, and we thought, ‘Let’s try to blend the two and make the best of both,’” said Turner Scholl, project manager for Wellhead.
Scholl said a control system automatically communicates with the gas turbine to produce the desired output. The battery allows the resource to remain synchronized to the grid, which is “a big advantage” for a quick response. The EGT keeps the 10-MW battery “tank” full, allowing the combined hybrid resource to always be available with no minimum off or on times.
Scholl said there had been quantifiable environmental benefits. Following the installation of an EGT at Southern California Edison’s Center Peaker in Norwalk, there was a 60% reduction in greenhouse gas emissions and a 78% drop in particulate emissions. There were also 50% fewer starts and 60% fewer run hours.
Additionally, Scholl said that as decarbonizing the grid eventually excludes fossil fuels, the technology is adaptable and able to rely more on the battery, which can be expanded in size, especially as prices continue to drop.
“Once you do these hybrids, you will have an existing interconnection, inverters, storage,” Scholl said. “And the way we see it is, over time you can expand the storage component and start replacing the capacity of your gas turbine and increase the size of this battery we’ve installed to eventually take the place of the gas turbine.”
Laurel Meeks, business development manager at Duke Energy, said there would be a “significant increase in renewable generation across the fleet.” While some renewables and storage may be standalone, Meeks noted a lot of it would be hybrid as well. That leads to the question of what the optimal renewables-plus-storage configuration is, “but no matter the configuration, the more flexible hybrid resource can certainly provide a wide variety of grid values at the distribution, transmission and generation level,” she said.