(21d) Bringing Value to Waste Through Gas Fermentation

Waste gas streams are produced in many process industries, where they are either used as a fuel source, or simply are flared before being released to the atmosphere.  Gas streams rich in carbon dioxide, water, carbon monoxide and/or hydrogen also can be produced through combustion or gasification of solid waste streams such as municipal solid waste, forestry residues, or agricultural residues, where the resulting gas stream is used to produce heat and/or power.  In both of these cases, the main driver is to reduce the waste stream, or to convert a toxic species such as carbon monoxide to something more benign such as carbon dioxide, as well as to extract value by production of power and/or heat.

Biological fermentation of carbon monoxide rich gas streams provides an alternative route to conversion of these waste streams.  The LanzaTech process produces ethanol and other high-value fuel and chemical products from renewable resources that feed on these gas streams.  The carbon monoxide rich gas stream can contain any amount of hydrogen, providing an opportunity to process waste streams from a wide range of industries.  The brings a significant upgrade in value to the carbon in the waste stream as compared to heat or power production, as well as an opportunity to reuse the carbon rather than release it as CO2 to the atmosphere.