Consumptive Water Use from Electricity Generation in the Southwest under Alternative Climate, Technology, and Policy Futures

Abstract

This research assesses climate, technological, and policy impacts on consumptive water use from electricity generation in the Southwest over a planning horizon of nearly a century. We employed an integrated modeling framework taking into account feedbacks between climate change, air temperature and humidity, and consequent power plant water requirements. These direct impacts of climate change on water consumption by 2095 differ with technology improvements, cooling systems, and policy constraints, ranging from a 3-7% increase over scenarios that do not incorporate ambient air impacts. Upon additional factors being changed that alter electricity generation, water consumption increases by up to 8% over the reference scenario by 2095. With high penetration of wet recirculating cooling, consumptive water required for low-carbon electricity generation via fossil fuels will likely exacerbate regional water pressure as droughts become more common and population increases. Adaptation strategies to lower water use include the use of advanced cooling technologies and greater dependence on solar and wind. Water consumption may be reduced by 50% in 2095 from the reference, requiring an increase in dry cooling shares to 35-40%. Alternatively, the same reduction could be achieved through photovoltaic and wind power generation constituting 60% of the grid, consistent with an increase of over 250% in technology learning rates.

Quantification of the water-use reduction associated with the transition from coal to natural gas in the US electricity sector

“…Water intensity of electricity could increase if pollution control or carbon capture and sequestration (CCS) techniques are implemented to reduce emissions from fossil fuel plants [17,26,29,30]. Previous studies of the water impacts of CCS implementation, have estimated an increase of 0.50 m 3 MWh −1 in water consumption and 0.73 m 3 MWh −1 increase in water withdrawal for supercritical pulverized coal plants at 40% carbon capture, and a 0.16 m 3 MWh −1 increase in water consumption for an NGCC plant at 40% carbon capture [29].…”

“…The literature examining the water-energy nexus over the past decade has grown substantially, with a focus on electricity generation constraints due to impacts of climate change and water stress [5,[9][10][11][12][13][14][15][16]. Assuming the same electricity generation profile of today, it has been estimated that water consumption in the southwest US will increase 3%-7% by 2095 [17]. However, rapid changes in the electricity sector, including increased utilization of wind and photovoltaic energy, along with retrofits of thermal plants with dry cooling systems, suggests that water consumption could rather decrease by up to 50% [17].…”

“…Assuming the same electricity generation profile of today, it has been estimated that water consumption in the southwest US will increase 3%-7% by 2095 [17]. However, rapid changes in the electricity sector, including increased utilization of wind and photovoltaic energy, along with retrofits of thermal plants with dry cooling systems, suggests that water consumption could rather decrease by up to 50% [17].…”

“…Recent reports examining the threats that climate change pose to the future US economy highlight the reduction in CO 2 emissions that could be achieved by decommissioning coal plants [8,12,[17][18][19][20]. Nonetheless, with natural gas becoming the predominant energy source for the electricity sector, the intensification of shale gas production in the US, and the significant increase in the intensity of water consumption of this process [21], raises questions about the implications of the transition from coal to natural gas on water availability.…”

Regional responses to future, demand-driven water scarcity

“…A few other basins in Western US and Central China also take additional responses in the agriculture sector, while both countries have a sizable power sector and the capacity to adapt in electricity generation. In particular, the potential of adapting through cooling-technology mainly exists in Central and Eastern US where most once-through cooling systems are currently installed; while water is already limited in Western US and there is little room to further reduce electricity water withdrawals over the century (Macknick et al 2012b, Averyt et al 2013, Liu et al 2015, Talati et al 2016. The California River basin, for instance, already has very small electricity water withdrawals and thus takes additional responses in agriculture to reduce irrigation water withdrawals by lowering crop production that mainly relies on irrigated agriculture ( figure S8).…”