Life cycle assessment of gasoline and diesel produced via fast pyrolysis and hydroprocessing

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.