Publication DetailsTitle : Energy and Emission Benefits of Alternative Transportation Liquid Fuels Derived from Switchgrass: A Fuel Life Cycle Assessment (abstract)
Publication Date : August 01, 2006
Publication Journal : Biotechnology Progress, Volume 22: 1012-1024 (2006)
Authors : M. Wu, Y. Wu, M. Wang
Abstract : We conducted a mobility chains - or well-to-wheels (WTW) - analysis to assess the energy and emission benefits of cellulosic biomass for the U.S. transportation sector in the years 2015 to 2030. We estimated the life-cycle energy consumption and emissions associated with biofuel production and use in light-duty vehicle (LDV) technologies by using the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model. Analysis of biofuel production was based on ASPEN Plus model simulation of an advanced fermentation process to produce fuel
ethanol/protein, a thermochemical process to produce Fischer-Tropsch diesel (FTD) and dimethyl ether (DME), and a combined heat and power plant to co-produce steam and electricity. Our study revealed that cellulosic biofuels as E85 (mixture of 85% ethanol and 15% gasoline by volume), FTD, and DME offer substantial savings in petroleum (66-93%) and fossil energy (65-88%) consumption on a per-mile basis. Decreased fossil fuel use translates to 82-87% reductions in greenhouse gas emissions across all unblended cellulosic biofuels. In urban areas, our study shows net reductions for almost all criteria pollutants with the exception of carbon monoxide (unchanged), for each of the biofuel production option examined. Conventional and hybrid electric vehicles, when fueled with E85, could reduce total sulfur oxide (SOx)
emissions to 39-43% of those generated by vehicles fueled with gasoline. By using bio-FTD and bio-DME in place of diesel, SOx emissions are reduced to 46-58% of those generated by diesel-fueled vehicles. Six different fuel production options were compared. This study strongly suggests that integrated heat and power co-generation by means of gas turbine combined cycle is a crucial factor in the energy savings and emission reductions.
Other Related DocumentsTitle : Updated Sugarcane and Switchgrass Parameters in the GREET Model
Publication Date : October 10, 2011
Authors : J. B. Dunn, J. Eason, M Q. Wang
Abstract : The feedstock from which a biofuel derives can have a significant effect on its life-cycle energy consumption and emissions of greenhouse gases (GHG). The aim of this document is to describe our approach to developing GREET parameters for key facets of sugarcane and switchgrass feedstocks that affect their life-cycle air emissions and energy consumption from the field (including the upstream energy to manufacture agricultural inputs such as fertilizer) to the conversion facility gate in the case of switchgrass. For sugarcane ethanol, we also revise aspects of the fuel's life cycle pertaining to the conversion facility including ethanol yield and embodied energy in the sugarcane mill buildings and equipment. A summary of data sources for corn stover and forest residue are provided elsewhere (Han et al. 2011). Note that although this document discusses switchgrass in the context of ethanol production, this crop could also be a feed to a process that directly produces hydrocarbon fuels, such as fast pyrolysis.