Comparative Life-Cycle Assessments for Biomass-to-Ethanol Production from Different Regional Feedstocks
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- 作者：Amber J. Kemppainen and David R. Shonnard
- 刊名：Biotechnology Progress
- 出版年：2005
- 出版时间：August 2005
- 年：2005
- 卷：21
- 期：4
- 页码：1075 - 1084
- 全文大小：364K
- 年卷期：v.21,no.4(August 2005)
- ISSN：1520-6033
文摘
This study compares life-cycle (cradle-to-gate) energy consumption and environmentalimpacts for producing ethanol via fermentation-based processes starting with twolignocellulosic feedstocks: virgin timber resources or recycled newsprint from an urbanarea. The life-cycle assessment in this study employed a novel combination of computer-aided tools. These tools include fermentation process simulation coupled with an impactassessment software tool for the manufacturing process life-cycle stage impacts. Theprocess simulation file was provided by the National Renewable Energy Laboratory(NREL) and was modified slightly to accommodate these different feedstocks. For thepremanufacturing process life-cycle stage impacts, such as the fuels and processchemicals used, transportation, and some preparatory steps (wood chipping, etc.), alife-cycle inventory database (the Boustead Model) coupled with an impact assessmentsoftware tool were used (the Environmental Fate and Risk Assessment Tool). TheNewsprint process has a slightly lower overall composite environmental index (createdfrom eight impact categories) compared to the Timber process. However, the Timberprocess consumes less electricity, produces fewer emissions in total, and has less of ahuman health impact. The amount of life-cycle fossil energy required to produce ethanolis 14% of the energy content of the product, making the overall efficiency 86%. Processimprovement strategies were evaluated for both feedstock processes, including recycleof reactor vent air and heat integration. Heat integration has the greatest potentialto reduce fossil-derived energy consumption, to an extent that fossil-derived energyover the life cycle is actually saved per unit of ethanol produced. These energy efficiencyvalues are superior to those observed in conventional fossil-based transportation fuels.