Biogas Methane as a feedstock for sustainable bio-processing

This is a Biotechnology and Biological Sciences Research Council (BBSRC) Anaerobic Digestion Network Seeding Catalyst Award project.
The Aim: To explore the feasibility of use biogas methane as a feedstock to produce chemical commodities using methane consuming bacteria as a process organism in gas fermentation.
The Need: Biogas methane, the main product of anaerobic digestion (AD), is an energy-rich feedstock with an energy density of 55.7 MJ/kg at 1.013 bar, 15 ºC. Raw AD biogas is roughly 60% methane and 29% CO2 with trace elements of H2S. The methane concentration is insufficient for direct use as fuel gas for machinery and the H2S is highly corrosive to the mechanical components. Considerable money and effort has to be expended in the purification of methane and for its combustion to generate electricity.
The Solution: We convert biogas methane through a biological process to the polymer, polyhydroxybutyrate (PHB), which can be easily converted into a wide variety of different plastics. From a business standpoint, it makes more sense to use methane as a feedstock than to burn it for power production. PHB sells for $3 to $4 a kilogram on today’s market, while methane burned for electricity production would return as little as 40 to 80 cents a kilo.