Civil & Environmental Engineering, Oklahoma State University, Stillwater, OK, USA.
Civil Architectural, and Environmental Engineering, Illinois Institute of Technology, Chicago, IL, USA.
Sci Total Environ. 2021 Aug 15;782:146770. doi: 10.1016/j.scitotenv.2021.146770. Epub 2021 Mar 27.
Lignocellulosic biomass such as switchgrass can be converted to n-butanol using fermentation, which can be further processed into jet fuel. Traditional acetone-butanol-ethanol (ABE) fermentation only converts sugars derived from switchgrass to ABE. Novel co-fermentation processes convert sugars and gas (CO/H) produced during fermentation into butanol, thus increasing ABE yields by 15.5% compared to traditional ABE fermentation. Herein, the environmental impact of a Switchgrass to Jet Fuel (STJ) pathway was assessed using life cycle assessment (LCA) from well-to-wake. LCAs were performed for greenhouse gas (GHG) emissions from jet fuel production via co-fermentation of sugars and gas for ideal and practical cases of ABE fermentation and seven other jet fuel pathways. The ideal case assumes 100% sugar recovery and 95% ABE yield. The practical case assumes 90% sugar recovery and an 80% ABE yield. Results are presented based on 100-year global warming potential (GWP) per MJ of jet fuel. Co-products were allocated using various methods. The increase in butanol yield via the co-fermentation technology reduced GWP-100 for the STJ pathway by 6.5% compared to traditional ABE fermentation. Similarly, the STJ pathway for the practical case with co-fermentation had 14.2%, 47.5%, 73.8%, and 44.4% less GWP-100 compared to HRJ, Fischer-Tropsch jet fuel from switchgrass, Fischer-Tropsch jet fuel from coal, and conventional petroleum jet fuel. The results demonstrate that the STJ pathway via co-fermentation has the potential to increase product yield while reducing GHG emissions compared to other jet fuel production pathways.
木质纤维素生物质，如柳枝稷，可以通过发酵转化为正丁醇，然后进一步加工成喷气燃料。传统的丙酮丁醇乙醇（ABE）发酵仅将源自柳枝稷的糖转化为 ABE。新型共发酵工艺将发酵过程中产生的糖和气体（CO/H）转化为丁醇，从而使 ABE 产量比传统 ABE 发酵提高 15.5%。本文采用生命周期评价（LCA）方法，从摇篮到门口，评估了柳枝稷到喷气燃料（STJ）途径的环境影响。对通过共发酵糖和气体生产喷气燃料的温室气体（GHG）排放进行了 LCA，包括理想和实际的 ABE 发酵以及其他七种喷气燃料途径。理想情况假设糖的回收率为 100%，ABE 收率为 95%。实际情况假设糖的回收率为 90%，ABE 收率为 80%。结果基于每兆焦耳喷气燃料 100 年全球变暖潜能值（GWP）呈现。使用了多种方法对副产品进行了分配。与传统 ABE 发酵相比，共发酵技术提高了丁醇的产量，使 STJ 途径的 GWP-100 降低了 6.5%。同样，对于共发酵的实际情况，STJ 途径与 HRJ、柳枝稷费托合成喷气燃料、煤费托合成喷气燃料和传统石油喷气燃料相比，GWP-100 分别减少了 14.2%、47.5%、73.8%和 44.4%。结果表明，与其他喷气燃料生产途径相比，通过共发酵的 STJ 途径具有提高产品产量和减少温室气体排放的潜力。
