Evaluating options for balancing the water-electricity nexus in California: Part 2-Greenhouse gas and renewable energy utilization impacts

- Part I presents a spatially and temporally resolved model of California's surface reservoirs.
- Part II presents GHG emissions and grid renewable penetration for water availability options.
- In particular, the energy signature of water supply infrastructure is delineated.
- Different pathways for securing California's water supply are developed quantitatively.
- Under baseline conditions, portfolios capable of securing surface reservoir levels emerge.
- Under climate change conditions, the water supply must be carefully selected to allay emissions.

A study was conducted to compare the technical potential and effectiveness of different water supply options for securing water availability in a large-scale, interconnected water supply system under historical and climate-change augmented inflow and demand conditions. Part 2 of the study focused on determining the greenhouse gas and renewable energy utilization impacts of different pathways to stabilize major surface reservoir levels. Using a detailed electric grid model and taking into account impacts on the operation of the water supply infrastructure, the greenhouse gas emissions and effect on overall grid renewable penetration level was calculated for each water supply option portfolio that successfully secured water availability from Part 1. The effects on the energy signature of water supply infrastructure were found to be just as important as that of the fundamental processes for each option. Under historical (baseline) conditions, many option portfolios were capable of securing surface reservoir levels with a net neutral or negative effect on emissions and a benefit for renewable energy utilization. Under climate change augmented conditions, however, careful selection of the water supply option portfolio was required to prevent imposing major emissions increases for the system. Overall, this analysis provided quantitative insight into the tradeoffs associated with choosing different pathways for securing California's water supply.