Taiwan’s ITRI introduces cellulosic bio-butanol production technology; pathway with highest carbon conversion yield
ITRI (Industrial Technology Research Institute), a Taiwan-based high-tech applied research institution, is introducing ButyFix, a technology for cellulosic bio-butanol production with a negative carbon footprint. ButyFix uses a three-step process: (1) the hydrolysis of cellulose and hemicellulose to release sugars; (2) fermentation of the sugars to produce butyrate; and (3) the chemical conversion of butyrate via esterification and hydrogenation to butanol.
ITRI uses a metal salt/organic acid “eco-solvent” in its hydrolysis process; the crystalline structure of cellulose is first destroyed, forming a soluble ester, which is then hydrolyzed by the organic acid to glucose. The process operates in mild temperatures; benchmarking results cited by ITRI show a 95 wt.% total sugar yield.
ITRI uses proprietary processes to regulate certain genes in specially adapted micro-organism and re-directs the CO2 generated during fermentation to the desired pathway where the CO2 can be re-utilized. This results in high yields of butyrate and eliminates CO2 emissions from the fermentation process.
ButyFix has a theoretical maximum carbon conversion yield of 100%, ITRI says, meaning that all carbon can be fixed in the product by fermentation if the process is optimized. By contrast, all other current fermentation processes for ethanol or butanol production have a theoretical maximum carbon conversion yield of 67% because of two molecular CO2 emitted per glucose molecule consumed.
|ITRI says that ButyFix is the leader in yield. Source: Tong 2013. Click to enlarge.
ITRI has shown it can achieve a butyrate yield of 0.70 g/g-sugar, which is 94% of carbon conversion yield. This carbon yield is 2.67 times of traditional acetone-butanol-ethanol (ABE) process. The same strain can also convert different sugars at relatively high efficiencies.
ButyFix butanol can achieve a transportation-fuel price of US$2.00/gallon, according to ITRI—well below current gasoline and bio-ethanol prices and without government subsidies.
ButyFix is available for licensing to biofuel- and chemical-processing organizations. ITRI received a 2013 R&D 100 Award for this development.
Alex Tong (2013) Introduction to a Disruptive Bio-butanol Technology (presentation at BIT’s 3rd Annual World Congress of Bioenergy-2013 Nanjang, China, 25-27 April 2013)