Impacts Of Non-electric Energy Low-Carbon Transition On Water Consumption:Based On Hybrid LCA Modeling

The Paris Agreement aims to achieve net-zero anthropogenic greenhouse gas(GHG)emissions during the second half of this century,which requires a deep low-carbon transition of energy systems.In addition to evaluating the technical and economic feasibility,the design of the energy transition pathway also requires systematic consideration of resource and environmental benefits,especially water resources.Current studies mainly focus on power sector,while there is a gap on the systematic and quantitative research on the impacts of water consumption in the non-electric energy system's large-scale low-carbon transition.To assess the carbon/water footprint of non-electric energy in major emitting economies at single technology level and the water consumption impacts in the shortterm and long-term low-carbon scenarios,a global multi-regional integrated hybrid life cycle model was built.The study selected 7 major economies and 6 types of non-electric energy as research objects,and carried out a localized full life-cycle carbon/water footprint study and a technology need assessment based on synergies.We further established a sustainability assessment system based on carbon-water coupling,systematically evaluated the impacts of non-electric energy transition in current NDC(Nationally Determined Contribution)and NDC to 2 degrees scenarios.Then the study analyzed water consumption impacts of multiple factors such as concentration target and technological progress in the long-term low-carbon transitions,and identified potential water resource risks.The results show that non-electric energies' low-carbon transitions have complex impacts on water resources in terms of absolute quantities,structural effects,carbon-water synergy effects and geographical distribution.(1)From single technology perspective,natural gas heating has a common carbon-reduction and water-saving synergy,which can reduce total life-cycle carbon emissions of 36-65%,especially in Japan,87% of huge water-saving effect is to achieve.Increasing capital intensity in the agriculture sector can reduce the complete water intensity of fossil fuels in developing countries.Non-electric energy from renewable sources does not necessarily have low-carbon properties,such as biogas heating.(2)Under current NDC scenario,water consumption of non-electric energy in Brazil,Russia,India,China,and the US decrease by 7-11% compared to baseline scenario.Among them,the incremental water in China and India is higher than in other economies;increasing the NDC stringency by 5% can promote multi-country carbon-energy,water-energy decoupling,and achieve carbon-reduction and water-saving synergies.China and US have the most significant benefits,which can reduce 5.6 Gt carbon/14 Gt water,and 2.4 Gt Carbon/8.1 Gt water during 2005-2030,respectively.(3)Strengthening long-term concentration target from BAU target to 450 ppm can help BRIC+US achieve non-electric energy's carbon-saving and water-saving synergies,with the most significant declines in China and US,in which 246 Gt carbon/540 Gt water and 62 Gt carbon/244 Gt water is reduced during this centuries,but bioethanol will universally affect the synergies.Increasing energy use efficiency by 50% can bring common watersaving benefits,and it is an effective and efficient water-saving pathway for China,India,EU27,and Japan.(4)In the long-term scenarios,the water pressure distribution is significantly uneven.China and India,which have the largest water demand,instead undertake the highest incremental water pressure brought by low-carbon transition,and the long-term mitigation action will further enlarge the water pressure gap between them and the other countries.