Rising concerns about the environmental impacts of fossil transportation fuels have motivated the development of alternative sources of energy that are renewable and environment-friendly. Biomass-derived liquid hydrocarbon fuels, offer an immediate "drop-in" alternative for displacing petroleum-derived transportation fuels, owing to their ability to use existing infrastructure. However, biomass, as an energy source is disadvantaged in terms of carbon and energy content. The Billion Ton Report 2016 predicts 1.3 billion tonnes of harvestable biomass in the U.S. by 2030. The carbon and energy content of this amount of biomass is not sufficient to support the demands of the U.S. transportation sector alone. Furthermore, traditional bioenergy systems like cellulosic fermentations to ethanol (CE), lose 1/3rd of the biomass carbon as CO2 and fail to utilize lignin ( 030340% of biomass energy) for fuel production. This calls for biomass conversion technologies that retain most of the biomass carbon and efficiently capture the inherent biomass energy in the produced liquid fuels. This can be achieved via fast pyrolysis that can convert all biomass (including lignin) to predominantly liquid bio-oil. However, this bio-oil is unstable, due to the presence of reactive functional groups. This fact combined with its low energy content makes it unfit as a fuel or a stable intermediate. In this regard, electrocatalytic hydrogenation (ECH) can harness renewable electricity from solar/wind farms and sufficiently hydrogenate the pyrolysis bio-oil to generate a stable intermediate that can be transported over long distances. Additionally, ECH employs mild conditions that allows it to be implemented at a local small-scale facility. This offers a key advantage in a bioenergy system, where transporting the low bulk density biomass can incur large transportation costs. The denser ECH-ed bio-oil can hence be transported at lower costs to conventional hydroprocessing facilities to produce a gasoline/diesel range fuel.In this study, a bioenergy system (Py-ECH) was developed that combines fast pyrolysis with ECH at decentralized depots, followed by hydroprocessing at a central refinery. The mass, carbon and energy flux through the system and the fuel yields were estimated. The fuel yields for the Py-ECH system were found to be better than CE in terms of energy, mass and carbon.To evaluate the economics of Py-ECH, a full techno-economic analysis was conducted using a discounted cash flow rate of return (DCFROR) approach and nth plant assumptions. The minimum fuel selling price (MFSP) of the Py-ECH fuel was found to be $ 3.62/gge (in 2018 $) compared to $ 3.70/gge (in 2018$) for CE. Through sensitivity analyses, key cost-contributing parameters were identified, and a pathway was charted for MFSP reduction to < $3/gge (in 2018 $).The environmental impacts of Py-ECH were investigated by performing a cradle-to-grave life cycle assessment for environmental impact categories of global warming potential (GWP), eutrophication potential (EUP) and water scarcity footprint (WSF). While the EUP and WSF for the Py-ECH system were lower than that for CE, it was observed that the GWP was dependent on the source of electricity in the Py-ECH system. Major improvements were identified that can result in a carbon negative Py-ECH system.Finally, a kinetic model was developed to examine the kinetics of the electrochemical, surface and adsorption/desorption reactions for the ECH of phenol (a model bio-oil compound) to cyclohexanol. The experiments were performed in a rotating disk electrode setup with Ru/ACC catalyst as the working electrode and an Ag/AgCl reference electrode to define the effects of mass transport.
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