Wind and Solar Resource Droughts in California Highlight the Benefits of Long-Term Storage and Integration with the Western Interconnect

Abstract

As reliance on wind and solar power for electricity generation increases, so does the importance of understanding how variability in these resources affects the feasible, cost-effective ways of supplying energy services. We use hourly weather data over multiple decades and historical electricity demand data to analyze the gaps between wind and solar supply and electricity demand for California (CA) and the Western Interconnect (WECC). We quantify the occurrence of resource droughts when the daily power from each resource was less than half of the 39-year daily mean for that day of the year. Averaged over 39 years, CA experienced 6.6 days of solar and 48 days of wind drought per year, compared to 0.41 and 19 for WECC. Using a macro-scale electricity model, we evaluate the potential for both long-term storage and more geographically diverse generation resources to minimize system costs. For wind-solar-battery electricity systems, meeting California demand with WECC generation resources reduces the cost by 9% compared to constraining resources entirely to California. Adding long-duration storage lowers system costs by 21% when treating California as an island. This data-driven analysis quantifies rare weather-related events and provides an understanding that can be used to inform stakeholders in future electricity systems.

What Can Be Learned from Spatial Economics?

“…Despite these limits, spatial models have proven to be a powerful tool in empirical works devoted to the retail sector (see Aguirregabiria and Suzuki 2016 for a survey). 1 1 Spatial competition models are also the backbone of the political science theory of party competition in…”

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“…Additionally, correlation within a resource across space or correlation between wind and solar resources, represents a challenge to robust, continuous generation of electricity because a reduction in one resource would typically be associated with a simultaneous reduction in the other [12]. Thus, the ability to transmit electricity over large geographic areas is advantageous not only because it is most economically efficient to site wind and solar farms at relatively remote locations where it is climatologically windiest and sunniest, but also because pooling resources over large areas reduces the correlation between and within resources, making the total energy supply less variable [18][19][20][21][22][23].…”

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