This is an extract from a recent paper by Himali Parmar, Vice President, Energy Advisory Services, Interconnection and Transmission and Biwan Zhou, Manager, Power Markets, ICF
Offshore wind is moving westward and is expected to play a crucial role in the overall power generation supply mix in the Western U.S. in the coming decades. When superimposed over the East Coast, the California coastline extends from Maine to North Carolina. The harnessing of its offshore wind resources will be necessary for California to achieve its zero-carbon energy resources supply goal by 2045.
As of November 2021, just a few offshore wind projects—with a modest combined capacity of 6.5 GW—were active in the California Independent System Operator (CAISO) interconnection queue versus 76 GW of solar and 11.5 GW of onshore wind. However, there is strong momentum from a policy and planning standpoint to expand the renewable base to other technologies including offshore wind.
Even though the Preferred System Portfolio adopted by California Public Utilities Commission (CPUC) in the 2019 Integrated Resource Plan did not include any offshore wind projections, CPUC has requested a sensitivity case in the CAISO’s 2021-2022 transmission planning process to assess the cost of upgrading transmission to accommodate 8.3 GW of offshore wind by 2031, with the potential to increase this offshore wind capacity up to 21.1 GW. The Biden administration proposal for a U.S.-wide deployment of 30 GW of offshore wind by 2030 will serve as an impetus to offshore wind development as will the agreement between the Departments of Interior and Defense to “advance areas for offshore wind off the northern and central coasts of California,” which they anticipate could bring up to 4.6 GW of new capacity to the grid.
In line with these findings, the U.S. Bureau of Ocean Energy Management (BOEM) has identified five proposed locations or “Call Areas” along the California coastline, considered to have superior wind resource potential: Diablo Canyon Call Area, Morro Bay Call Area, Morro Bay Call Area East Extension, and Morro Bay Call Area West Extension— all in central California—plus Humboldt Call Area in Northern California.
Flatten the California duck curve
While solar is expected to continue to dominate the future supply mix, increasing levels of solar penetration will intensify the duck curve effect. Another challenge of a solar-dominated grid comes when extreme weather conditions restrict solar radiation over consecutive days.
To address these grid reliability issues, CAISO, CPUC, and other stakeholders have recently put into motion several significant changes and reforms including a major reduction in reliance on solar for meeting reserve requirements by decreasing its effective load carrying capacity (ELCC). This has been accompanied by the adoption of new resource adequacy methodologies, specifically placing more emphasis on evening peaks and the examination of multiple hours instead of just the peak load hour. ICF’s assessment of the renewable generation and demand profiles shows that offshore wind has a stronger diurnal coincidence with California load profile compared to solar, especially in the evening hours. By shaving the peak demand in the early evening, offshore wind can potentially reduce the slope of the duck curve by providing a gradual ramp in the early evening when solar generation declines.
Moreover, while overall California demand peaks in the summer, northern areas such as Humboldt and the Central Coast in the PG&E service territory experience highest demand in the winter. Offshore wind aligns better with seasonal demand profile as compared to solar.
Power flow dynamics today
The bulk power system in California is connected through a 500-kV transmission system consisting of commercially significant interfaces—most notably Path 15 and Path 26. Solar resources are expected to continue to penetrate in Southern California, particularly in the Kern and Big Creek areas that are located between Paths 15 and 26. Due to the location of the solar resources, one would expect significant congestion in the South to North direction on Path 15 and North to South direction on Path 26 during solar hours, creating potential chokepoints for the Morro Bay and Diablo Canyon Call Areas. The most sustained wind output, however, will be injected during non-solar hours muting the effects of these mid-day bottlenecks.
California offshore wind development has sufficient tailwinds with support from both federal and state governments. Offshore wind’s profile may help to alleviate California’s duck curve issues, and also aligns better with the winter peaking Northern California grid. Hence, we expect it to be a crucial part of the future supply mix. The power grid in Central California may have available injection capacity; however, significant transmission chokepoints are observed for the Humboldt Call Area in Northern California. ICF’s assessments shows $500 million-$600 million of network upgrades will be required to integrate 1 GW of offshore wind.
The complete paper can be accessed here