Shang-Tian Yang, a professor of chemical and biomolecular engineering at Ohio State University announced last week at the American Chemical Society meeting that he has engineered a mutant bacterium that doubles his butanol process output.
Readers will recall that butanol is a near direct replacement for gasoline with nearly the same energy density and burning properties. But butanol is a difficult product to source from biomass. Currently butanol is used in chemical processes and as a solvent sourced from petroleum. Even from petroleum butanol is priced at or above $3.00 a gallon before taxes, the lure of a biomass sourced direct replacement is so very tempting.
Normally, bacteria could only produce a limited amount of butanol – perhaps 15 grams of the chemical for every liter of water in production tank – before the tank would become too toxic of butanol for the bacteria to survive. Yang and his colleagues’ mutant strain of the bacterium Clostridium Beijerinckii lives and works in a bioreactor containing bundles of polyester fibers. In that environment, the mutant bacteria produced up to 30 grams of butanol per liter while surviving. This is a doubling level of improvement, but 30 grams is still only 3% by volume.
The new bacterium’s life in the new fibrous bed bioreactor should improve production. The patent abstract states, “The cells are immobilized onto the surface of and within convoluted sheets of a fibrous support material and reactant bearing fluids are caused to flow between the opposing surfaces of such convoluted sheets. . . . The product may be extracted from its aqueous media by high distribution coefficient solvents.” This might be a way to upgrade the butanol output.
But what is left out from the patents and the news releases are the hard data on the proportion of the source carbohydrates upgraded to the butanol product. With ethanol moving inexorably to cellulosic raw material feedstocks, butanol is way behind. It’s not for want of trying though. Butanol at 4 carbon atoms is much less bio friendly stuff for production than the 1 and 2 carbon atom products of methanol and ethanol.
Yang isn’t missing the whole point saying, “Today, the recovery and purification of butanol account for about 40 percent of the total production cost. Because we are able to create butanol at higher concentrations, we believe we can lower those recovery and purification costs and make biofuel production more economical.”
The goal it seems to me would be to get to 100% consumption of the carbohydrates going in, as ethanol production does, which is very close now to getting the whole of the grain and sugar cane carbohydrates made back into fuel.
But the market driving forces might change too fast for butanol. Personal transporters like cars, motorcycles and e-bikes might as a market move too fast for butanol to make a major splash. The fuel cell technology seems destined, the anti carbon crowd notwithstanding, to be headed to light hydrocarbons and alcohols instead of straight hydrogen.
The news from Ohio State is worthwhile. A sustainable source of 4-carbon butanol is going to be a market of some noteworthy size for decades if not centuries to come. But the major efforts with deep pockets are from BP a major oil company and Dupont the huge chemical company who have teamed up to crack a new process. Little news has been coming for a couple of years. A tight listing of the news is here, which includes some of the research and privately financed ventures groups.
Looking out into the future holds one key point, the response by consumers to their need for lower costs for getting the work done. Efficiency and conservation may have taken a recess in the demand destruction of the current recession, but by no means will the recession last or stay entrenched across so much of the world’s economy. That thought puts gasoline and butanol in a darkening future for growth with alternatives likely to see a brighter picture. As wealth building recovers, the chance could be that the gas-guzzler might come back, but more likely the wealth will go to much more efficient and conserving kinds of personal transport vehicles.
An economical high efficiency fuel cell fueled by light alcohols or petroleum at one or two carbon atoms per molecule with a wide operating temperature to recharge batteries or capacitors would signal the end of internal combustion power sets. Where butanol might fit in such a future is more likely to be fuel for heavy equipment and in flight kinds of equipment.
If research can get going with more major caliber kinds of breakthroughs in butanol the internal combustion engines could have much longer roles in powering people’s workloads. By all means a natural source of butanol for chemical supplies is worthwhile. Yet this writer, for all the enthusiasm for continuation of the status quo in preserving and raising living standards, finds the building of new more efficient products more of an economy booster than a continuation of the past’s simple burning to thermal to mechanical powered systems doing the work.
A couple of years ago butanol had a huge opportunity, but the march of technology continues on, leaving butanol pointed to a market that if sense has any input, will shrink in the coming decades unless the optimal fuel cell runs on butanol. Now that might be a research effort that might become important in the coming years if the production issues can be worked out.
Enthusiasm here is high for butanol, it’s just the range and market depth of that applications looks to be narrowing.