Lifecycle assessment of microalgae to biofuel [electronic resource] : Comparison of thermochemical processing pathways
- Washington, D.C. : United States. Dept. of Energy. Office of Energy Efficiency and Renewable Energy, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages 1,062-1,071 : digital, PDF file
- Additional Creators:
- Idaho National Laboratory, United States. Department of Energy. Office of Energy Efficiency and Renewable Energy, and United States. Department of Energy. Office of Scientific and Technical Information
- Restrictions on Access:
- Free-to-read Unrestricted online access
- Microalgae are currently being investigated as a renewable transportation fuel feedstock based on various advantages that include high annual yields, utilization of poor quality land, does not compete with food, and can be integrated with various waste streams. This study focuses on directly assessing the impact of two different thermochemical conversion technologies on the microalgae to biofuel process through life cycle assessment. A system boundary of a “well to pump” (WTP) is defined and includes sub-process models of the growth, dewatering, thermochemical bio-oil recovery, bio-oil stabilization, conversion to renewable diesel, and transport to the pump. Models were validated with experimental and literature data and are representative of an industrial-scale microalgae to biofuel process. Two different thermochemical bio-oil conversion systems are modeled and compared on a systems level, hydrothermal liquefaction (HTL) and pyrolysis. The environmental impact of the two pathways were quantified on the metrics of net energy ratio (NER), defined here as energy consumed over energy produced, and greenhouse gas (GHG) emissions. Results for WTP biofuel production through the HTL pathway were determined to be 1.23 for the NER and GHG emissions of -11.4 g CO2-eq (MJ renewable diesel)-1. WTP biofuel production through the pyrolysis pathway results in a NER of 2.27 and GHG emissions of 210 g CO2 eq (MJ renewable diesel)-1. The large environmental impact associated with the pyrolysis pathway is attributed to feedstock drying requirements and combustion of co-products to improve system energetics. Discussion focuses on a detailed breakdown of the overall process energetics and GHGs, impact of modeling at laboratory- scale compared to industrial-scale, environmental impact sensitivity to engineering systems input parameters for future focused research and development and a comparison of results to literature.
- Report Numbers:
- E 1.99:inl/jou--14-32120
- Other Subject(s):
- Published through SciTech Connect.
Applied Energy 154 ISSN 0306-2619 AM
Bennion, Edward; Ginosar, Daniel; Moses, John; Agblevor, Foster; Quinn, Jason.
- Funding Information:
View MARC record | catkey: 23502345