http://synbioproject.tech/cpi/applications/isobutanol/
Isobutanol is a four-carbon alcohol that Gevo is developing from renewable feedstock (rather than petroleum) for the chemicals and fuels markets. The chemical is used in the manufacture of isobutyl acetate, which goes into lacquer, paint solvent, and varnish remover. Butanol stores more energy per volume, is less corrosive to pipelines, is more easily separated from water, and can be blended with petrol at higher concentrations than ethanol.
Gevo’s technology engineers enzymes that can convert waste and other cellulosic feedstocks into alternative fuels like isobutanol and butanol, reducing cost over petroleum-based products. According to press reports, the company plans to deploy the isobutanol using a “capital light” approach, which means existing ethanol-producing facilities can be retrofitted to use the chemicals.