Emergy based optimization of regional straw comprehensive utilization scheme

With the continuous development for the straw utilization industry, studying the sustainability of different straw utilization industries and the realization of the optimal distribution of regional straw utilization industries has become an important issue. This paper studied the straw utilization industry in Shandong through field investigation and literature research, and comprehensively evaluated these industries through emergy analysis. Results showed that the emergy-based sustainability indexes (ESI) of straw biogas (SBP) and feed productions (SFP) are both high, 1.61 and 1.49 respectively, which should be encouraged. ESIs of straw-based particleboard (SBPP) and straw-bioethanol production (SP) are low, 0.61 and 0.54 respectively, which should be restricted, and other ways could be developed appropriately. Moreover, a methodology combining emergy analysis and multi-objective programming was constructed to solve optimization of regional straw comprehensive utilization scheme. The results suggested that if the main goal was to improve the regional economy, the proportion of straw returning to the field (SRF) should be reduced and that of the SBP should be increased. If the environmental impact was the main optimization goal, then SRF should be the main straw treatment method. Furthermore, to avoid adverse effects on environmental benefits and sustainable development, it was recommended that more attention should be paid to avoid blindly pursuing the increase in the scale of straw utilization.