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

Abstract

• 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 climatechange 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. a b s t r a c t a r t i c l e i n f o

Global warming and changes in risk of concurrent climate extremes: Insights from the 2014 California drought

“…Using data from the 2014 California drought, we show that a univariate return period analysis based on precipitation, commonly used in hydrology, substantially underestimates the occurrence probability of the 2014 California drought because of ignoring the effects of temperature. This is even more important for regions like California where a drying trend has been observed [Damberg and AghaKouchak, 2014], and a warmer and drier climate is expected in future [Seager et al, 2007;Cayan et al, 2008Cayan et al, , 2010 with potential impacts on the ecosystem, water availability, energy production, and agriculture industry [Connell-Buck et al, 2011;Zhu et al, 2005;Tanaka et al, 2006;Lund et al, 2003;Madani and Lund, 2010;Tarroja et al, 2014aTarroja et al, , 2014b. Historically, California has faced summer fraught with difficult decisions as demands from farms that help feed the nation clash with the water needs of city residents.…”

Quantifying climate change impacts on hydropower generation and implications on electric grid greenhouse gas emissions and operation

“…This model has been used to examine perturbations such as increased variable renewable penetration [21], electrification and grid-integration of light-duty transportation through plug-in vehicles [22,23], and increased water infrastructure-related electric loads due to the reliance on alternative water supply measures to secure water resource supplies under climate change [24]. For this particular study, the perturbation of hydropower generation in a future climate is studied.…”

“…This study utilizes the water reservoir network model employed by Tarroja [24] for the network of major surface reservoirs in California (see also [26e28]). This model utilizes temporally resolved inflow and demand profiles for individual reservoirs with rules for the release and storage of water which have been calibrated from historical data for a 10-year period from 2000 to 2010.…”

“…More detail on the model development and details are provided by Tarroja [24]. All of these reservoirs are based on in-stream hydropower, and this does not include off-stream pumped hydropower reservoirs.…”

California drought increases CO2 footprint of energy

“…Droughts happen around the world and their cumulative impacts on CO 2 emissions are staggering. Water and energy are closely related and the two sectors can be managed to alleviate droughts without exacerbating CO 2 emissions (Tarroja et al, 2014). In many part of the world such as California, food production is also a major component of both the water and energy markets.…”