Patent ID: 8178329

Claim:
A method for producing a lower alkyl alcohol from anaerobic microbial fermentation of a gaseous substrate, the method comprising: a) culturing microorganisms in a fermentation broth in a reactor vessel and supplying to said reactor vessel said gaseous substrate comprising at least one gas selected from hydrogen, carbon monoxide, and carbon dioxide; b) manipulating partial pressure of each of said at least one gas selected from hydrogen, carbon monoxide, and carbon dioxide in the reactor vessel so that it is thermodynamically feasible to convert said gaseous substrate to greater than or about 5% lower alkyl alcohol of the fermentation broth by volume; and c) said culturing and manipulating steps causing said microorganisms in said reactor vessel to produce the lower alkyl alcohol in the fermentation broth, wherein concentration of said lower alkyl alcohol reaches greater than or about 5% of the fermentation broth by volume.