Long-term projections of global water use for electricity generation under the Shared Socioeconomic Pathways and climate mitigation scenarios

Abstract. Electricity generation may become a key factor that accelerates water scarcity. In this study, we estimated the future global water use for electricity generation from 2005 to 2100 in 17 global sub-regions. Twenty-two future global change scenarios were examined, consisting of feasible combinations of five socioeconomic scenarios of the Shared Socioeconomic Pathways (SSPs) and six climate mitigation scenarios based on four forcing levels of representative concentration pathways (RCPs) and two additional forcing levels, to assess the impacts of socioeconomic and climate mitigation changes on water withdrawal and consumption for electricity generation. Climate policies such as targets of greenhouse gas (GHG) emissions are determined by climate mitigation scenarios. Both water withdrawal and consumption were calculated by multiplying the electricity generation of each energy source (e.g., coal, nuclear, biomass, and solar power) and the energy source-specific water use intensity. The future electricity generation dataset was derived from the Asia-Pacific Integrated/Computable General Equilibrium (AIM/CGE) model. Estimated water withdrawal and consumption varied significantly among the SSPs. In contrast, water withdrawal and consumption differed little among the climate mitigation scenarios even though GHG emissions depend on them. There are two explanations for these outcomes. First, electricity generation for energy sources requiring considerable amounts of water varied widely among the SSPs, while it did not differ substantially among the climate mitigation scenarios. Second, the introduction of more carbon capture and storage strategies increased water withdrawal and consumption under stronger mitigation scenarios, while the introduction of more renewable energy decreased water withdrawal and consumption. Therefore, the socioeconomic changes represented by the SSPs had a larger impact on water withdrawal and consumption for electricity generation, compared with the climate mitigation changes represented by the climate mitigation scenarios. The same trends were observed on a regional scale, even though the composition of energy sources differed completely from that on a global scale.