Electrifying with High-Temperature Water Electrolysis to Produce Syngas from Wood via Oxy-Gasification, Leading to Superior Carbon Conversion Yield for Methanol Synthesis

• Main Authors: Sylvain Larose, Raynald Labrecque, Patrice Mangin
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Applied Sciences
• Subjects: biomass gasification; methanol production; solid oxide electrolysis; regional sustainability; electrification; carbon yield
• Online Access: https://www.mdpi.com/2076-3417/11/6/2672

Due to concerns regarding fossil greenhouse gas emissions, biogenic material such as forest residues is viewed nowadays as a valuable source of carbon atoms to produce syngas that can be used to synthesise biofuels such as methanol. A great challenge in using gasified biomass for methanol production is the large excess of carbon in the syngas, as compared to the H₂ content. The water–gas shift (WGS) reaction is often used to add H₂ and balance the syngas. CO₂ is also produced by this reaction. Some of the CO₂ has to be removed from the gaseous mixture, thus decreasing the process carbon yield and maintaining CO₂ emissions. The WGS reaction also decreases the overall process heat output. This paper demonstrates the usefulness of using an extra source of renewable H₂ from steam electrolysis instead of relying on the WGS reaction, for a much higher performance of syngas production from gasification of wood in a simple system with a fixed-bed gasifier. A commercial process simulation software is employed to predict that this approach will be more efficient (overall energy efficiency of about 67%) and productive (carbon conversion yield of about 75%) than relying on the WGS reaction. The outlook for this process that includes the use of the solid oxide electrolyser technology appears to be very promising because the electrolyser has the dual function of providing all of the supplemental H₂ required for syngas balancing and all the O₂ required for the production of a suitable hot raw syngas. This process is conducive to biomethanol production in dispersed, small plants using local biomass for end-users from the same geographical area, thus contributing to regional sustainability.