Water for energy: Characterizing co-evolving energy and water systems under twin climate and energy system nonstationarities

The energy system is a major water user, but understanding how much water is consumed and withdrawn for energy is a challenging empirical task: non-evaporative volumetric water use is not easily calculated from first principles. Water use also has impacts that differ in important ways depending on where water is abstracted and used, timing of use, and socioenvironmental context. Moreover, different decarbonization pathways and policy environments have very different water use implications. We currently face a crisis of twin non-stationarities in hydrology and energy systems that make understanding water use for energy critical for decision support as hydroclimate and energy systems change. Currently, water-for-energy data are highly uncertain and not centrally collected, which means researchers spend substantial effort collecting inventory data. Recent advances in impact assessment methods for water volumes focus largely on spatially resolved water scarcity evaluations, but robust conclusions can be elusive due to uncertain and low-metadata inventory information. As water-for-energy quantification efforts progress, research should emphasize decision support for energy system design, incorporating crucial hydrologic dynamics. Beyond the location of water use, relative scarcity, and potential competing uses, these include sub-daily to interannual temporal dynamics, the impacts of climate change on these dimensions, potential feedbacks between energy and water systems, and the impacts of hydrologic variability or change on policy-based incentive structures. This article reviews prior US-focused efforts to quantify water use for energy, highlights why these nonstationarities are analytically relevant with a brief policy case study, and highlights research needs for decision support under twin nonstationarities. This article is categorized under: Engineering Water > Sustainable Engineering of Water Engineering Water > Planning Water Engineering Water > Methods