Microwave pretreatment of rape straw for bioethanol production: Focus on energy efficiency
Abstract
The energy efficiency of microwave-assisted dilute sulfuric acid pretreatment of rape straw for the production of ethanol was investigated. Different microwave energy inputs and solid loadings were tested to find economic pretreatment conditions. The lowest energy consumption was observed when solid loading and energy input were fixed at 50% (w/w) and 54kJ (900W for 1min), respectively, and amounted to 5.5 and 10.9kJ to produce 1g of glucose after enzymatic hydrolysis and 1g ethanol after fermentation, respectively. In general, 1g ethanol can produce about 30kJ of energy, and therefore, the energy input for the pretreatment was only 35% of the energy output. The approach developed in this study resulted in 92.9% higher energy savings for producing 1g ethanol when compared with the results of microwave pretreatments previously reported.