Water usage for energy production and supply in China: Decoupled from industrial growth?

The energy industry, one of the largest water consumers in the socioeconomic system, has been constrained by water scarcity in some areas worldwide. Therefore, decoupling water usage from the energy system is a pressing issue for ensuring energy security and maintaining environmental sustainability. This study applied an input-output analysis and the Tapio decoupling index, which may be considered the first attempt to investigate the decoupling degree between water usage, i.e., the direct water withdrawal for energy production (WWEP) from a production-based perspective and the water footprint for energy supply (WFES) from a consumption-based perspective, and industrial growth for five major energy sectors in China from 2002 to 2015. We found that WWEP was roughly three times higher than WFES for the whole energy industry, and both values underwent a considerable decrease during the study period. Production and supply of electricity and heat (PSEH) contributed most to the total WWEP and WFES, and was mainly responsible for the overall decline. Moreover, WFES exceeded WWEP in Processing of petroleum, coking, and processing of nuclear fuel (PPC) and Production and supply of gas (PSG), whose WEFS values accounted for 36.3% and 12.2%, respectively, of the total WFES in 2015. In terms of the decoupling status, only PSEH achieved strong decoupling in both WWEP and WFES, while PPC and PSG presented a better decoupling performance for WWEP than that for WFES. In contrast, Mining and washing of coal and Extraction of petroleum and natural gas performed relatively worse from both perspectives. These results can help provide a foundation and support for effective water conservation policies from both energy production and energy consumption perspectives.