Life Cycle Assessment of Lignocellulosic Biomass Conversion Pathways to Hydrogenation Derived Renewable Diesel

  • Author / Creator
    Wong, Alain JL
  • Renewable fuels standards introduced in various jurisdictions aim at increasing the use of biofuels. There has been limited work on the life cycle assessment of the production of HDRD in terms of overall environmental impacts. This study is focused on conducting an LCA on the production of hydrogenation-derived renewable diesel (HDRD) from lignocellulosic biomass available in western Canada, especially Alberta, to fill the gap in knowledge. The focus of the study is on assessments of the life cycle greenhouse gas (GHG) and water requirement for the HDRD production pathway from lignocellulosic biomass. HDRD has better properties than biodiesel in terms of its use in colder climates like Canada and can be produced from lignocellulosic biomass. The GHGs emitted from the fossil fuel energy used in the HDRD production pathway are assessed for three types of feedstocks, whole tree, forest residues, and agricultural residues. The results reveal that the GHG emissions and net energy ratio (NER) (the energy output per unit fossil fuel energy input) for fast pyrolysis-based processes followed by processing lie in the range of 35.4 – 42.3 gCO2,eq/MJ HDRD and 1.55 – 1.90 MJ/MJ, respectively. HDRD from agricultural residues produces the least emissions and highest NER followed by whole tree feedstock, with forest residues having the most emissions and lowest NER. In addition to assessing the amount of GHG emissions and fossil-derived energy input, the life cycle water use requirements of HDRD production were also determined. This water use impact is extended to hydrothermal liquefaction (HTL) to study and compare two different types of conversion pathways. The water use requirements for whole tree and forest residues are 579.5 L H2O/MJ HDRD and 438.1 L H2O/MJ HDRD through fast pyrolysis and HTL, respectively. Agricultural residues had a lower water use requirement than whole tree and forest residues, valued at 83.7 L H2O/MJ HDRD and 59.1 L H2O/MJ HDRD through fast pyrolysis and HTL, respectively. Water use from biomass production make up almost all of the total water use required to produce HDRD; therefore agricultural residues, requiring less water for growth, have a lower water use requirement than the other two feedstocks. Another factor that affects the water use required for HDRD production is the HDRD yield. Biomass going through HTL followed by hydroprocessing gives a higher HDRD yield than biomass going through fast pyrolysis followed by hydroprocessing; therefore, a lower water use is required per unit MJ of HDRD for HDRD produced by HTL and hydroprocessing. The results of the study are helpful in making investment decisions and policy formulation associated with HDRD production from lignocellulosic biomass in Alberta.

  • Subjects / Keywords
  • Graduation date
    Spring 2016
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.