Switch Grass Can Be a Viable Alternate to Corn for Ethanol

An interesting source of alternative energy is the concept of biofuel from switch grass. Switch grass is a breed of quick growing grass, which has been considered by the US’s Department of Energy (DOE) as being economically sustainable as a much greener alternative source of fuel and could ultimately cut back on petroleum demand as well as no longer using food crops.

Panicum virgatum, otherwise known as switchgrass, is a very common species of bunch grass in North America. Its range extends from prairies in Canada all the way south to Mexico. It has numerous uses including forage cover, game cover and of course a source of bio fuel. It thought to be a very valuable source of liquid fuel and can go far to help America wean itself from petroleum based liquid based fuel. It is not quite as easy to obtain, because like a treasure safely guarded by booby traps, nature has developed its own natural defense for this rich source of a viable substitute for petroleum.

This natural defense present in the switch grass is a tough layer of woody material called lignin. This material is what guards the starch where the material to make ethanol is. A big challenge for our leading scientists in this area is finding an economically viable method of retrieving the polysaccharides from within the lignin and break down this polysaccharide into simpler fermentable sugars that can be chemically converted into liquid fuel or ethanol.

So as usual our scientists have risen to the occasion and come up with quite an ingenious solution to this problem. The scientists have discovered that introducing a variant corn gene into the species, makes some dramatic changes to the starch content of the plant, increasing it drastically (more than double).

This variant gene of the maize species, now corn grass now releases greater amounts of glucose during saccharification (the process of breaking down complex carbohydrates into simple monohydrates) and is now much easier for enzymes to break down; the gene restricts the species from reaching adult stage, hereby preventing the development of lignin. The bio fuel (ethanol) is gotten from the cellulose via either of two methods.

After saccharification, basically in the presence of enzymes (yeasts) and under controlled physical conditions the simple sugars are chemically converted anaerobically into carbon dioxide and ethanol as products of the metabolism. This ethanol is the required biofuel but it still has to go through distillation to obtain the final results of being pure ethanol.

This process does not rely saccharification but using partial combustion, the carbon content is converted into synthesis gas. This process doesn’t go through the usual fermentation with yeast but rather the gases are fermented with a micro organism called Clostridium ljungdahlii. The microorganism ingests the gases and produces ethanol and water.

This method of alternative energy is also fairly new and is still undeveloped in most countries, but I can see this cutting back a great deal on human consumption of liquid fuel from petroleum sources and provide a reliable source of greener fuel. It will also cut down our dependence on food crops such as corn to make ethanol.

Don Levy https://bioenergy.ornl.gov/papers/misc/switgrs.html Bioenergy Feedstock Development Program

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