Waste gases as feedstocks for advanced biofuels
Waste gases from energy plants and industrial processes can potentially be captured and converted to advanced biofuels. A number of projects have been developed that capture carbon dioxide and use it for cultivation of algae, which is then converted to biofuels.
Historically, biogas (LFG) produced from landfill sites has been another potential source of renewable energy. However issues such as gas migration, the long lifecycle of landfill sites (requiring many decades of management), the risk of toxic leachates, and a lack of available land mean that increasingly, efforts are being made to reduce the amount of waste material being buried in Europe and globally.
A preferred option now is for Municipal Solid Waste to be separated (at source or waste management centres) into different fractions: putrescible waste, recyclable materials and Solid Recovered Fuel SRF (the fraction of MSW that cannot be recycled e.g. shredded textiles, wood, paper, card and plastics. The SRF and organic waste both have high potential for bioenergy and biofuel production via gasification and anaerobic digestion, respectively.
EU funded projects
Steelanol aims at transforming carbon-rich industrial waste gases into advanced bio-ethanol for use in the transport sector by way of a novel gas-fermentation technology. The technology that will be developed and proven in this project will allow for the capture and reuse of a portion of carbon emitted by the steel industry without need to rebuild the BAT (Best Available Technologies) steel plant while supplying the transport sector with high grade biofuel, that does not compete in any way with food crops or land for food crops. Duration: 2015 -2018.
LanzaTech commercial ethanol facilities
Waste gases from industrial processes are also potential feedstocks for bioenergy and biofuels production. For example, LanzaTech, New Zealand, has developed a method for capturing carbon-rich waste gases from industrial steel production, which are then fermented and chemically converted for use as a jet fuel using microbes (developed via synthetic biology). The technology is being used in conjunction with Swedish Biofuels advanced processes for the conversion of alcohols into drop-in jet fuels.
In December 2014, LanzaTech announced a $60m equity investment from the New Zealand superannuation fund. In April 2015, China Steel Corp, Taiwan announced approval of a $46m (USD) investment in a LanzaTech commercial ethanol facility.
In 2016 the 'Integrated bioprocess for conversion of gaseous substrates to liquids' report, published in the Proceedings of the National Academy of Sciences (PNAS) journal, described the process of converting syngas – synthetic gas that predominantly includes a mixture hydrogen, carbon monoxide and carbon dioxide – into liquid lipids that can be used as fuels.
The bioconversion involves two main steps, the first of which processes syngas into acetic acid (concentrated vinegar) in an anaerobic bioreactor using bacteria. The acetic acid is then used as a substrate for an oil-producing yeast, which aerobically converts it into lipids (Source and read more: Biofuels International).