Cellulosic technology must use existing cropland — study

Source: Amanda Peterka, E&E reporter • Posted: Wednesday, March 20, 2013

Cellulosic biofuels can become profitable for farmers and help displace oil, but they must use already-available agricultural land, according to a study released by a nonprofit yesterday.

Commissioned by the Council for Agricultural Science and Technology, the study found that encouraging farmers to use agricultural residues and to engage in “double-cropping” would bring the industry further in the short term than relying on planting new acres of switch grass and other perennial energy crops.

“It starts with the residue,” said co-author Bruce Dale, a chemical engineering professor and biofuels expert at Michigan State University. “We use the corn residues and other residues and start building the cellulosic biofuel industry with them.”

While a handful of companies have begun producing cellulosic biofuels at a commercial scale, the industry is still in its infancy, generating 20,000 gallons last year. Once the second-generation biofuels industry reaches the 250-million-gallon mark through using available land, the market can feasibly be expanded to dedicated biofuel crops, Dale said yesterday at a briefing on the study.

“As the costs come down through learning by doing, then more crops start getting planted, dedicated crops for cellulosic biofuels, because you’ve established the markets, supply chains start to become working, technology is established, and people will invest in it,” he said.

The findings are part of a larger look at food, fuel and plant nutrient use during the next 40 years, when global population is expected to expand by nearly 35 percent to more than 9 billion people.

World grain production will need to increase by about 50 percent in that time period, with the largest increases coming in developing countries.

In the United States, the current rate of growth in agriculture is sufficient to meet the increased demand, the report says, but it could put strains on the environment through increases in fertilizer use and other nutrient sources.

Using existing lands for biofuel crops would help lessen the strains of agricultural land on the environment. Agricultural residues such as corn stover provide the greatest opportunity for advanced biofuels in the short term, the authors said.

At least 1.5 billion tons of crop and forest residues is available globally for cellulosic biofuel production. According to a previous study by Dale, there is enough agricultural waste in the world to produce 560 billion liters of ethanol annually, or 70 percent of the energy content of all U.S. gasoline. Adding in production on former land that is abandoned or unused, it would be possible to produce enough biofuel for 750 billion liters of ethanol a year.

Double-cropping, or planting separate winter crops on corn and soybean lands, could also be an early driver of the cellulosic biofuels industry, the study found.

Double crops are currently grown on less than 10 percent of corn acres because they represent a cost to the farmer and not much revenue. Approximately 180 million dry metric tons of double crops could be annually grown on existing U.S. corn and soybean acres if farmers bought into such a management system.

Those crops could become more attractive to farmers if biofuel pretreatment methods produce protein as a byproduct, the authors said. That protein could be converted to animal feed and provide an additional revenue stream.

Such systems render the “food versus fuel” argument null, they argue.

“The analysis of this paper shows that the United States can produce very large amounts of biofuels, maintain domestic food supplies, continue the contribution to the international food stock, increase soil fertility, and significantly decrease greenhouse gas emissions,” the report concludes. “Resolving the apparent ‘food versus fuel’ conflict seems to be more a matter of making the right choices rather than hard resource and technical constraints.”

The study is co-authored by University of California, Berkeley, agricultural economics professor David Zilberman; International Plant Institute Senior Vice President Paul Fixen; and North Carolina State University soil science professor John Havlin.