As bio-ethanol is developing rapidly, its impacts on food security, water security and the environment begin to receive worldwide attention, especially within the Water–Energy–Food nexus framework. The aim of this study is to present an integrated method of assessing sweet sorghum-based ethanol potential in China in compliance with the Water–Energy–Food nexus principles. Life cycle assessment is coupled with the DSSAT (the Decision Support System for Agrotechnology Transfer) model and geographic information technology to evaluate the spatial distribution of water consumption, net energy gain and Greenhouse Gas emission reduction potentials of developing sweet sorghum-based ethanol on marginal lands instead of cultivated land in China. Marginal lands with high water stress are excluded from the results considering their unsuitability of developing sweet sorghum-based ethanol due to possible energy–water conflicts. The results show that the water consumption, net energy gain and Greenhouse Gas emission reduction of developing sweet sorghum-based ethanol in China are evaluated as 348.95 billion m3, 182.62 billion MJ, and 2.47 million t carbon per year, respectively. Some regions such as Yunnan Province in south China should be given priority for sweet sorghum-based ethanol development, while Jilin Province and Heilongjiang Province need further studies and assessment.

Facing water and land scarcity, planting non-food biofuel crops on marginal land depending on natural rainfall has been considered as an attractive means of achieving sustainable biofuel development. However, the complex connection between rainfall and marginal land resources in spatial-temporal distribution affects the optimal planting layout of non-food biofuel crops as well as the assessment of biofuel potential, especially in arid areas. In this study, we constructed a water-land-biofuel nexus centered on non-food biofuel crops, optimized the layout of three non-food biofuel crops, sweet sorghum, Jerusalem artichoke and switchgrass, based on fuzzy mathematics method under the water-land-biofuel nexus perspective, determined yield-rainfall curve to calculate the development potential of non-food biofuel crops. The results showed that sweet sorghum and Jerusalem artichoke are more suitable for planting in Ningxia. Three potential scenarios are set up under different growth conditions and agricultural technologies. The theoretical biofuel production is [9.64× 10⁷, 10.93× 10⁷] GJ, which was verified by the result that the biofuel production per unit area is close to the lower limit of the test production range. It can also be speculated that there may exist irrigation supply and fertilization in the actual crops planting in other studies.