The paper compares selected life cycle-based (well-to-wheel) studies of fuel/propulsion alternatives for light-duty vehicles with a focus on lignocellulose-derived fuels (hydrogen, Fischer Tropsch liquids, and ethanol). Inter- and intra-study comparisons are completed and analyses are conducted to account for the variability due to differing assumptions surrounding energy accounting and vehicle characteristics. For lignocellulose-derived fuels used in relevant propulsion systems, life cycle greenhouse gas emissions are on average 96% lower for hydrogen, 91% lower for Fischer Tropsch liquids and 86% lower for ethanol as compared to the reference gasoline pathway. Key issues found to impact study results are assumptions regarding feedstock characteristics, vehicle propulsion system efficiency, land use changes and associated carbon sequestration, nitrous oxide emissions due to agricultural practices, co-product allocation, energy accounting practices, and expected progress on commercial-scale fuel production processes and associated infrastructure.(A) "Reprinted with permission from Elsevier".
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