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Cellulosic ethanol plans on track
The path toward second-generation ethanol -- made from cellulosic sources such as crop residues, wood chips, and municipal waste -- has not been smooth, but it is still on track, say experts in the topic.
Claus Fuglsang, head of the bioenergy division of Novozymes (www.Novozymes.com), said at a farm media conference this week in California that if crude oil is above $75 a barrel, a system for turning biomass products such as corn stalks or sawdust can be competitive economically. Novozymes is the largest producer of the enzymes that, when mixed with corn or cellulose, convert starch to sugar. The sugar is then fermented into alcohol.
"It's harder for the enzymes to attack and break apart cellulose," Fuglsang said. "The starch in corn grain is relatively easy to break down, but that's not true of cellulose." For example, he says, the cost of the enzymes is 3 to 4 cents per gallon of ethanol produced from corn. But it may take 50 cents of enzymes to convert cellulose to ethanol. Those enzymes are more specialized, it takes more of them, and it takes longer.
Also, corn grain is about 85% starch, while cellulose can be as low as 30%, further diminishing the efficiency of cellulosic ethanol. And, the ethanol feedstocks are bulky and harder to transport, generally limited to a 50-mile radius from a plant.
Still, Fuglsang is optimistic about cellulosic ethanol. His company has developed a new product called a cellulosic enhancer, GH61, that will break down the cellulose before the enzymes are added, gaining efficiency in the process. When added to new proprietary enzymes developed by Nonozymes, efficiency can be improved by a factor of 1.5, he says, and reduce production costs by as much as 10%. "I think we can get the total production cost for cellulosic ethanol down to $2 per gallon," he says similar to current costs for corn grain-based ethanol.
He also says this year is a big year for cellulosic biofuels. Several commercial plants have broken ground and will begin production with cellulosic feedstocks, enhancing the learning curve. When the new E15 gasoline standard kicks in, it will create the ethanol demand required to push cellulosic efforts forward, he predicts.
Meanwhile, a University of Calfornia-Berkeley researcher is also supporting efforts to develop second-generation biofuels such as cellulosic ethanol. Heather Youngs, a bioenergy analysis expert at the Energy Biosciences Institute of UC-Berkeley (www.energybiosciencesinstitute.org/), told the same media group that she's encouraged about the potential for cellulosic ethanol. She thinks we can hit government targets of 350 million gallons of cellulosic ethanol (out of about 15 billion gallons of total ethanol) by 2015. About a dozen cellulosic plants are in place or being planned now.
California has been a center of objection to the ethanol industry, especially the corn-based business. It's unsustainable, they say, and food should not be made into fuel. Youngs herself is not so strident in her views, saying the economics of corn-based ethanol are good and we have corn in surplus now. But long-term, the day will come when we need all of our corn for food, she says, and hopefully we'll have a different model in place by then for bioenergy. One part of that will include converting waste cellulose-based products to fuel.
In California, her Berkeley group has found that there are 87.7 billion tons of biomass waste produced every year. Only 12% is agricultural crop residue. Half is municipal waste, which she sees as a prime opportunity for turning into biofuel. "Up to now, the discussion about bioenergy has been about land use priorities," says Youngs. "I predict that is going to change to things like water use and resource inputs.
"The first plants for cellulosic ethanol are not the most efficient, but they'll get better as we move forward. And the costs are very expensive, up to half a billion dollars for a 50-million-gallon a year plant. That's a lot of risk."
One problem with cellulosic ethanol is that the the co-products are not as readily usable as distillers' grains from corn ethanol. After cellulose is processed, you are left with lignin, a plastic-like product that resists digestion. Perhaps its best use is to burn it for fuel to power the ethanol plant.