Cellulosic Biobutanol from Wheat Straw

I have written before that Butanol is a much more real, viable, and more serious contender as a gasoline replacement fuel than ethanol. There are many reasons for it, not least because it has high energy density, does not mix well and hence transports easily, and burns cleanly.

There are many reasons why I think biofuels still have a long way to go, esp those derived from bio-mass using enzymatic reactions. One key problem is the energy costs expended in the distillation process because the bacteria do not last in alcohol concentrations greater than 10%. hence the alcohol has to be distilled from a 90% water solution. That said, I think the scientific community (and entrepreneurial community) largely agrees that the real success of bio-enzymatic fuels will only happen when cellulosic alcohol problem is cracked. i.e. alcohol is derived by breaking down the complex lignocellulose that make up the bulk of the bio-mass available today for fermentation.

There many companies doing research on cellulosic ethanol: some with brighter futures and/or more influential backers than others. There are even more technologies still in academic labs waiting for the gestation period to be over so they cold be successfully commercialized. But here is some news on a laboratory success story on making butanol from wheat straw, a common and cheap bio feedstock available in many parts of the world. At least two problems remain: (a) reaction time in batch reactors, (b) distillation.

Cellulosic Biobutanol from Wheat Straw

from Green Car Congress by Mike Millikin

Scientists at the USDA Agricultural Research Services (USDA ARS) are exploring the production of cellulosic biobutanol from wheat straw using Clostridium Beijerinckii.

The research is part of a larger, ongoing research project: Cost-Effective Bioprocess Technologies for Production of Biofuels from Lignocellulosic Biomass.

In work to be published in the Journal of Biotechnology, Nasib Qureshi, Badal Saha and Michael Cotta achieved a rate of production of wheat straw hydrolysate to butanol of 214% over that from glucose.

Wheat straw contains about 70% complex carbohydrate that can serve as a low cost feedstock for conversion to fuel ethanol.

Clostridium beijerinckii P260 can utilize five and six carbon sugars present in cellulosic biomass and convert them to butanol. The researchers pretreated wheat straw with dilute sulfuric acid and hydrolyzed it using commercial carbohydrases to lignocellulosic component sugars (glucose, xylose, arabinose, galactose, and mannose) prior to their conversion to butanol.

Hydrolysis, fermentation, and product recovery were combined in a single step using a 2.5-liter bioreactor. Fermentation performance was enhanced by simultaneously recovering products [Acetone-butanol (AB)] from the fermentation broth by gas stripping, thereby avoiding inhibition of the end product.

The reactor operated in a fed-batch mode, and fermentation lasted for more than 500 hours.



2 Responses to Cellulosic Biobutanol from Wheat Straw

  1. Hamza says:

    Mr Zuberi. You seem to doubt ethanol’s viability as an alternative energy fuel. I agree with you. Not only is ethanol inefficient as a fuel, the fact that increased usage of corn based ethanol will drive up food prices is likely to change food security dynamics for millions across the world.

    I’m particularly interested in the the types of biofuels that are relevant to the energy strategies of developing countries. So, I was wondering what your views are on Jatropha? In many countries, particularly in India & parts of Africa (Mali is spearheading the effort), Jatropha is being promoted as an sustainable biofuel. The Jatropha plant can survive (and prosper) in semi arid areas, thus eliminating the need for costly irrigation projects. Most importantly for developing countries, since the plant doesn’t compete for growing space with food crops, , It doesn’t effect the food supply. Since the Jatropha planting effort is being based in semi arid areas of Rajastan in India (and with sind sharing a similar climate), do you see any future for Jatropha in Pakistan? Given the current dire energy situation in Pakistan, it may be a useful exercise to see whether Jatropha based biofuel could be used for development in Pakistan. We could take a leaf out of the biofuel strategies of other developing countries.

    Jatropha in Mali:

  2. I found an article for you bhai, i hope it comes very useful to you. Here is the link http://www.williamkamkwamba.typepad.com/ . In this article the poor people make windmill from recycled materials.

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