Towards Electrobiofuels: Economics and Environmental Impacts

Abstract

Our changing climate necessitates a transition to biomass-based hydrocarbon fuels to power aviation, shipping, and long-haul trucks that service essential supply chains to deliver food, textiles, and other consumer goods including electronic devices. To accomplish this transition, renewable energy systems are needed that efficiently deconstruct biomass and superimpose non-carbon emitting electrical energy with bioenergy to increase output energy in liquid fuels. Fast pyrolysis and electrocatalytic hydrogenation (py-ECH) is a technology sequence that first converts biomass into a liquid, known as bio-oil, which is then electrocatalytically hydrogenated to stabilize its properties. Products formed after py-ECH include linear and branched polyols, tetrahydrofurans, and alkyl cyclohexanols. Evidence of lignin oligomer cleavage has also been observed, as has the subsequent appearance of monomeric cyclohexanols. Building on these encouraging results, the commercialization potential of py-ECH was determined by economic analysis and life cycle assessment. These analyses co-locate ECH after pyrolysis at decentralized biomass upgrading depots, with the aim of stabilizing pyrolysis bio-oil for subsequent transport to centralized hydroprocessing refineries. The results of these analyses suggest that electrocatalytic hydrogenation is the keystone technology for coupling non-carbon emitting electrical energy with biomass carbon to generate a greater amount of liquid fuel than otherwise possible. A pathway to liquid fuel less than $3 per gallon of hydrocarbon equivalent fuel can be established, especially if renewable electricity is provided at low cost. Finally, “electrobiofuels” can be made with negative net carbon emissions with well-managed agriculture, biochar soil amendment, and when renewable electricity powers ECH.