AP. Borole, AJ. Lewis
Electro-Active Techologies, LLC,
United States
Keywords: bioelectrochemical conversion, electrosynthesis, hydrogen
Summary:
Production of green diesel and gasoline requires a renewable source of hydrogen. Biomass contains up to 40% oxygen, thus, deep deoxygenation requires significant amounts of hydrogen. Bio-oil produced via pyrolysis contains over 35 wt.% oxygen present as carboxylic acids, aldehydes, ketones, furans and phenolic compounds. We report on a hybrid thermochemical – biological process to generate bio-oil intermediate and renewable hydrogen to support green fuel production. Use of microbial electrolysis for extraction of hydrogen from water-soluble carbon compounds associated with bio-oil is described, which has potential to increase the hydrogen as well as carbon conversion efficiency of the process. The conversion of key components of the bio-oil aqueous phase, including furfural, acetic acid and phenols to hydrogen will be discussed. Electroactive biofilms which utilize these components in the presence of inhibitory compounds present in bio-oil to generate clean electrons will be discussed. These electrons are then combined with protons to produce pure hydrogen. Up to 50% of the bio-oil can be converted into hydrogen, making it a potential source of green hydrogen as well. The pr ocess is based on bioelectochemical cell technology. We have demonstrated the conversion of various kind of biomass including switchgrass, pine wood, corn stover, willow and guayule, as well as municipal wastewater solids. A thorough analysis of the electroactive biofilm consortium was conducted to understand the current production characteristics 8. Besides kinetics, mass and charge transfer in MECs was evaluated and reported recently, leading to identification of major bottlenecks in achieving high performance. In addition, improvement in energy efficiency via reduction of overpotential has also been investigated. This has lead to improvement in hydrogen productivity reaching the levels needed for commercial feasibility of above 15 L/L-day. The work done in past five years has brought the technology to a level ready for investigations at pilot scale. Coupling of this technology with biorefineries can enable on-site hydrogen production w-hile cleaning the bio-oil for fuel production. The microbial community active in the anode chamber employs division of labor and syntrophy between exoelectrogens and fermenting organisms to efficiently convert a broad range of compounds to hydrogen. The substrate specificity of the consortium was diverse and included Gammaproteobacteria, Betaproteobacteria, Clostridia and other families. The integrated biocatalytic-electrocatalytic approach offers a new direction for conversion of biomass into green products.