Assessing the influence of freshwater consumption priorities on zero-carbon electricity planning: A case of Senate Bill 100 compliance in California

Abstract:

In support of developing robust energy decarbonization strategies, efforts to characterize the advantages and disadvantages of different electricity resource mixes to develop zero-carbon electricity systems are critical. Many of these assessments, however, evaluate different mixes with the objective of minimizing electricity costs with little to no accounting of regional environmental externalities and may not capture unintended environmental consequences of developing their preferred electricity mix. In California, a region that has implemented a zero-carbon electricity goal by 2045 in California Senate Bill 100, is also subject to water scarcity issues that must not be exacerbated by the development of a decarbonized electricity system. This study therefore combines electric grid dispatch modeling with region-specific life cycle freshwater consumption data to compare how four different electricity mix scenarios compliant with California Senate Bill 100 compare on the bases of in-state freshwater consumption and levelized cost of electricity. The modeled scenarios show that electricity costs are lowest when resource mixes are composed to reduce the need for energy storage capacity through reliance on high capacity factor and dispatchable renewables, but these mixes also exhibited the highest freshwater consumption due to their reliance on geothermal resources. In contrast, the mixes that rely exclusively on wind, solar, and hydropower due to high energy storage capacity needs exhibited the highest costs of 30% above the lowest cost mix, but these mixes also exhibited freshwater consumption one order of magnitude lower than the lowest cost mix. Overall, our results show that the inclusion of regional environmental externalities such as freshwater consumption as a co-priority will alter the composition of a decarbonized electricity mix compared to a sole focus on cost metrics.