(Invited) Increasing Biogas to Liquid Fuel Yield By Solid Oxide Co-Electrolysis of Biogas CO2 Fraction

Abstract

OxEon Energy, LLC (OxEon) plans to demonstrate production of liquid hydrocarbon fuels using both the methane and CO2 generated in a food waste digester operated by the Environmental Products & Technologies Corporation (EPT). The EPT food waste digester in Burley Idaho sells produced biogas into a natural gas pipeline after separating and venting the bio-CO2. This project will convert the bio-methane to synthesis gas (syngas, as CO & H2) using a non-thermal plasma catalyzed autothermal reformer. To achieve high bio-carbon utilization, an OxEon high temperature solid oxide co-electrolysis (HTCE) system will electrochemically generate additional syngas from the bio-CO2 combined with steam raised by cooling the Fischer Tropsch (FT) reactor. Syngas from the reformed methane and co-electrolyzed CO2, will be converted to liquid fuels using an OxEon developed FT reactor. Each of the technology components have been field tested independently and will be combined for the first time in this project. The project outcome will be an engineering scale demonstration of liquid hydrocarbon bio-fuel production achieving > 50% conversion to liquids of the biogenic carbon in both CH4 & CO2 produced by an anaerobic digester.Each of the three technology elements of the integrated engineering test incorporates numerous innovations. The plasma reactor is designed to be fuel flexible, sulfur tolerant, and economically scalable to small, distributed bio-gas resources. It is also very efficient using a low power non- thermal plasma. High temperature solid oxide electrolysis has demonstrated efficiency at the thermodynamic limit as shown by analysis and testing at DOE and NASA laboratories, and is unique in its ability to co-electrolyze steam and CO2 directly to syngas. The HTCE stacks use innovations proven for the NASA Mars 2020 project which required exceptional ruggedness and effective high temperature seals. The FT reactor enables economical fabrication of smaller size synthetic fuel plants designed to match the scale of distributed renewable biomass resources. This is achieved with large diameter standard piping combined with a novel internal thermal management structure.The status of the technology elements and the planned engineering demonstration will be presented.This work is supported by the Bioenergy Technologies Office of the US Department of Energy.