Presented by Dr. Edward Frank, Advanced Biofuels Scientist, Argonne National Laboratory
Nov 2, 2011
Researchers around the world are developing sustainable plant-based liquid transportation fuels (biofuels) to reduce greenhouse gas emissions and reduce petroleum consumption. Algae are attractive because they promise large yields per acre compared to grasses, grains, and trees. Algae thus mitigate potentially large land-use change effects associated with other crops. Algae produce oils that can be converted to diesel and gasoline equivalents in current refineries while other biofuels like ethanol and biodiesel require expensive production and distribution infrastructure modifications as well as vehicle changes. It takes considerable energy to produce algal biofuels with current technology and an outstanding question is how much energy and greenhouse gas benefits algal biofuels can provide compared to petroleum fuels when one considers the critical supply-chain stages in the fuel pathway. This is challenging because of technology uncertainties; thus, previous algal biofuel studies on energy and emission effects show diverse results. Argonne National Laboratory released a detailed study that identified key parameters that affect answers to this question. The study concluded that with a baseline scenario, GHG emission reductions for algae-based fuels are affected by a few critical factors such as energy use for water movement, algal oil extraction, and treatment of algae biomass residues. In particular, the study concluded that the anaerobic digestion process that is commonly used in algal biofuel models has the potential to produce substantial greenhouse gas emissions and that alternative scenarios, e.g., catalytic hydrothermal gasification, may avoid these emissions. The work produced and utilized an expanded version of Argonne's GREET model for modeling energy consumption and emissions in transportation systems. The work was supported by the Office of Biomass Program within the Office of Energy Efficiency and Renewable Energy of the U.S. Department of Energy.