Wednesday, 16 October 2019: 15:05
Room 312 (The Hilton Atlanta)
According to the 2016 Billion Ton Report, the annual harvestable biomass in the U.S. (that can be produced at $60/ton or less) by the year 2030 is not sufficient to meet the annual energy demands of the U.S. transportation sector alone. Therefore, for biomass-derived fuels to be considered a realistic alternative to fossil fuels, processes must be developed to upgrade the energy content of these biofuels to match that of petroleum-based fuels. Such energy upgrading must also overcome the barriers resulting from biomass’ dispersed nature and the high costs of transporting a low bulk density feedstock. Depot-based fast pyrolysis partially overcomes these barriers by densifying biomass into bio-oil, however this mixture is reactively unstable and corrosive. Subsequent electrocatalytic hydrogenation (ECH) potentially stabilizes this bio-oil to a form that can be transported and stored at a centralized refinery. ECH involves using mild temperature, atmospheric pressures and renewable electricity, such as wind or solar, to split water on a catalytic cathode to produce in situ hydrogen and consequently perform the reduction of reactive aromatic compounds present in bio-oil. For the bioenergy system studied, the catalytic cathode was selected to be ruthenium on activated carbon cloth with a platinum anode. Bio-oil was modelled as a mixture of eight compounds, each species representing a key functional group. To investigate the merits of this biofuel production strategy, mass, energy and carbon flow analyses were performed for the proposed system. These were compared to the traditional approach of cellulosic ethanol fermentations as described in a 2011 report by NREL. The comparative study revealed the advantages of the proposed process in terms of mass, carbon, and energy efficiency. More recently, a full scale “cradle-to-grave” life cycle assessment (LCA) was performed to quantify the environmental impacts of the proposed process, such as global warming, eutrophication, and water use. As suspected, the LCA analyses revealed that the electrical power source plays a major role in determining the overall climate change potential of systems that upgrade biomass using electrocatalytic hydrogenation. A full-scale economic analysis was also performed to estimate the minimum fuel selling price (MFSP) and to elucidate the most sensitive parameters affecting the MFSP. The LCA and the techno-economic analysis are integral steps in the commercial application of the proposed bioenergy system.
