14 DAY TRIAL // People consider ethanol (biofuel) as being a solution to replace gas as this has reached high prices (up to $3-a-gallon) and the oil resources are finishing, being forecast to drop significantly in 30 years, not mentioning that most petroleum-rich nations are unreliable, non-democratic and unstable nations. Ethanol is currently made of corn grains, but this result is still costly; using the plant's inedible parts (biomass) would make the cost more efficient.
"Converting biomass would add value to the corn residues that are currently not used," said genetic engineer Mariam Sticklen of Michigan State University.
But turning corn leaves and stalks into useful sugars might become complicated and costly. That's why Sticklen's team has genetically engineered corn plants that produce by themselves the enzymes that break down their own tissues. For the moment, three undisclosed companies are interested in the mutant corn.
There are cars in US already running on gasoline mixed with some small ethanol levels (about 10 %). But fermenting corn grain to get ethanol is not sustainable.
"We have a limited amount of corn grain. Even if everyone went on maize-free diets and put every ear of corn into ethanol, it would meet only 15 % of U.S. transportation fuel needs", Sticklen said.
The solution would be employing corn's biomass, made of cellulose, a sugar polymer. To turn cellulose into ethanol, it must be broken down first to glucose by an enzyme named cellulase. Turning glucose into ethanol is the easiest step (in fact, grains' starch is broken down first to glucose, too, but the starch's break down is a much easier process).
In the last 5 years, cellulase technology cost decreased 25 times, due to genetically engineered bacteria that carry the cellulase gene and break down the cellulose.
"Still, cellulose-derived ethanol costs about $2.30 a gallon. To compete with other fuels, the price needs to come down to between $1.00 and $1.50," Sticklen said.
The enzymes are programmed to start digesting the cellulose only when the biomass is crushed up and heated. This technology would make the ethanol production cheaper, but for the moment there are no large-scale cellulose-derived ethanol facilities.
The mutant corn is developed in such a way as to control where the cellulase forms, so that the enzyme won't disintegrate the kernels we eat. Moreover, the cellulase genes do not enter the pollen grains, so that they cannot be transmitted through simple reproduction, nor spread into nearby corn fields.