Friday, June 10, 2011

Life Cycle Analysis (LCA) of Gasoline and Diesel David Hsu recently published the report 'Life Cycle Assessment of Gasoline and Diesel Produced via Fast Pyrolysis and HydroprocessingPDF.' In this work, a life cycle assessment (LCA) estimating greenhouse gas (GHG) emissions and net energy value (NEV) of the production of gasoline and diesel from forest residues via fast pyrolysis and hydroprocessing, from production of the feedstock to end use of the fuel in a vehicle, is performed. The fast pyrolysis and hydrotreating and hydrocracking processes are based on a Pacific Northwest National Laboratory (PNNL) design report. The LCA results show GHG emissions of 0.142 kg CO2-equiv. per km traveled and NEV of 1.00 MJ per km traveled for a process using grid electricity. Monte Carlo uncertainty analysis shows a range of results, with all values better than those of conventional gasoline in 2005. Results for GHG emissions and NEV of gasoline and diesel from pyrolysis are also reported on a per MJ fuel basis for comparison with ethanol produced via gasification. Although pyrolysis-derived gasoline and diesel have lower GHG emissions and higher NEV than conventional gasoline does in 2005, they underperform ethanol produced via gasification from the same feedstock. GHG emissions for pyrolysis could be lowered further if electricity and hydrogen are produced from biomass instead of from fossil sources.
Economic analysis of a pyrolysis process design by Pacific Northwest National Laboratory has shown that for an “nth plant,” the minimum fuel selling price is $2.04/gal of fuel (2007 dollar basis). A similar study by ConocoPhillips, Iowa State University, and NREL showed that an “nth plant” could result in a fuel product value (defined as the value that yields a net present value of zero with an internal rate of return of 10%) of just over $2 per gallon of gasoline equivalent (2007 dollar basis), which is lower than fuel product values from comparable studies on ethanol via a biochemical pathway and gasoline/diesel via gasification followed by Fischer-Tropsch catalysis. In addition to the competitive fuel prices, pyrolysis may have additional cost savings by potentially using existing petroleum refinery infrastructure for hydrotreating and hydrocracking.
The full report is available free of charge at

National Renewable Energies Laboratory (NREL)
April 6, 2011

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