Crop straw, a renewable resource, holds a crucial position in transition towards alternative, clean bioenergy. However, there is a dearth of analysis on the land- and water-saving potential associated with producing bioenergy from crop straw instead of clean energy. To comprehensively address these deficiencies, we conducted a face-to-face field survey for deep analysis. Our results revealed that most crop straw in the five southern provinces of China is retained in the field or openly burned, less for energy utilization. However, we also found that promoting bioenergy production potential from crop straw is significant and could meet the current energy demand for transportation or households in the five southern provinces. The production of briquette fuel and bioethanol from crop straw can significantly reduce GHG emissions of 23.3 Mton and 23.2 Mton, respectively, compared with coal and gasoline consumption. Furthermore, our study illustrated that replacing energy crops like Jerusalem artichoke with crop straw to produce bioethanol could reduce 11% of the total sown area occupied and save 3% of the irrigation water used in the five provinces. In conclusion, this study offers a more sustainable and efficient approach to producing bioethanol and other bioenergy while minimizing environmental impact and reducing resource consumption.