Production of low carbon fuels and chemicals from biogas through a hybrid thermochemical/biochemical gas fermentation process

Biogas presents a unique feedstock opportunity due its high thermal content and the fact biogas is generally produced from waste organic sources. Currently most biogas is flared or vented due to the collection challenges and limited volume availability. Biogas is being produced from a waste source and is underutilized presenting a distinctive opportunity for low-cost, sustainable waste to energy (WTE).

Gas fermentation is a biological process in which microbes convert climate-active gases, such as methane, carbon monoxide, or carbon dioxide, into low-carbon fuels and chemicals. LanzaTech currently operates a gas fermentation process that utilizes biological renewable resources to convert carbon monoxide to ethanol and other fuel derivatives. Biogas can be readily reformed to syngas through a variety of conventional thermochemical technologies, which can be converted to energy through gas fermentation. Gas fermentation has a number of distinct advantages over conventional thermochemical gas-to-liquid (GTL) routes, including syngas composition flexibility, reduced economic operating scale, and reduced gas clean-up requirements, providing cost and emissions benefits.

The integrated thermochemical/biochemical LanzaTech gas fermentation process waste to energy from biogas is described including process economics and life cycle analyses; there is also active research on the direct fermentation of methane to fuels which will also be described. There are many biogas assets that are currently uneconomical to exploit due to relatively low available volumes and/or high costs of gas collection. Gas fermentation presents an enabling technology for small-scale deployment and accessing sources that are currently uneconomical to process and may be ultimately flared or vented.