CLIMATE CHANGE ALTERS INTERREGIONAL ELECTRICITY DYNAMICS ON THE U.S. WEST COAST

Power systems and markets are influenced by hydrometeorological variability, including temperature-driven changes in electricity demand and water availability impacts to hydropower. The U.S. Pacific Northwest (PNW) meets over 55% of its regional electricity demand with hydropower, a majority of which is produced within the Federal Columbia River Power System. California relies on hydropower produced in-state and imported electricity the PNW to meet demand, leaving California vulnerable to West Coast wide hydrologic variability. As hydroclimate changes across this region, a combination of forces may work in tandem to make West Coast power markets even more susceptible to reliability and price risk. A warmer climate is expected to shift the timing of streamflow earlier in the year and increase summer cooling demand. In this work, we investigate how climate change could alter interregional electricity market dynamics on the West Coast, including the possibility that hydroclimate changes in one region (e.g. PNW) could compound price and reliability risks in another (e.g. California) and vice versa. Power system metrics (generation, demand, market prices) are analyzed for multiple combinations of downscaled Global Climate Models (GCMs), Representative Concentration Pathways (RCPs), hydrologic models and timescales. We find that under static grid conditions, climate change across the West Coast could cause higher average annual wholesale prices and reduced reliability. We find that hydroclimatic risks for the PNW power system are largely driven by changes in streamflow, while risks for the California system are driven by changes in summer air temperatures, particularly extreme heat waves increasing peak system demand. In addition, we find that climate change conditions in the PNW (including altered timing and amounts of hydropower exports to California) have little impact on reliability and prices in the California market -- unless compounded by climate change conditions in California. However, climate conditions in California have a significant impact on outcomes in the PNW, especially when compounded with shifts in the timing of PNW hydropower generation.