Fermentation turns greenhouse gases into useful chemicals

A carbon-negative process that produces industrial-scale quantities of acetone and isopropanol has been developed by researchers in the US. Their work could lead to the replacement of some emissions-heavy chemical production methods with more flexible and environmentally friendly processes.

According to the International Energy Agency, the chemical-production sector is the single largest industrial consumer of oil and gas and the third largest carbon emitter, putting out just short of a gigatonne of carbon dioxide emissions in 2020. Acetone and isopropanol (IPA) are two widely employed commodity chemicals used as industrial solvents and platform chemicals for materials production, with a combined global market worth $10bn. Unfortunately, they are manufactured from fossil resources using highly energy-intensive techniques that release hazardous waste and greenhouse gas (GHG) emissions.

As the climate crisis intensifies, researchers are seeking alternative means to lessen the climate impact of producing these commodities. A newly released paper in Nature Biotechnology offers the first report of high-production-rate, high-selectivity, and industrially scalable production of acetone and IPA through fermentation.

Acetone and IPA are normally produced by propene cracking and reforming, which are energy-intensive processes with no green alternatives. Scientists have developed methods for biomanufacturing substances by the fermentation of sugars. This involves using natural enzymes and micro-organisms to metabolize these sugars and output the desired products. However, the techniques developed to date have low yields and selectivity, making commercialization unfeasible. Instead, the new study considered autotrophic production, using waste resources such as carbon oxides (carbon monoxide or carbon dioxide) from heavy industry, or syngas from biomass resources, as a starting point.