Cellulosic ethanol target of ISU research projects

While corn has been the source of choice for ethanol productionthus far, many experts say the future of the industry will include various biomass sources, beginning with corn stover.

”Eventually, there will be a transition from corn grain to corn stover to hopefully other forms of biomass,” says Robert Anex, associate director of biorenewables programs at Iowa State University.

”Corn grain is necessary to create a market for ethanol. There needs to be a network before people will invest in (biomass ethanol production),” he says.

For that reason, grants were awarded to several ISU researchers and others to look more closely at corn stover as a biomass for biofuel production.

Anex leads a team of researchers looking into harvest and storage methods, optimal plant genetics and efficient production systems for efficient and sustainable biomass fuel production.

Anex says they they are in the middle of a four-year project.

Researchers are looking at all possible variables of a corn stover biomass ethanol system.

”What is easy to harvest is not always easy to store,” Anex explains. ”The best variety for grain may not be the best variety for grain plus stover harvest.”

Researchers are working on a list of about 100 corn hybrids, ranking high those that would be the most suitable for biomass ethanol.

Anex says hybrids high in cellulous, low in lignin and have abundant foliage would be most suitable. But, they are also noting hybrids that have valuable grain and biomass for ethanol because, in many cases, both materials will be used in valuable markets.

Some researchers are searching for optimal harvesting methods for corn stover.

Stuart Birrell, ISU professor of ag and biosystems engineering, and colleagues developed a dual-system harvester that harvests corn stover and grain at the same time.

A dual system is beneficial because less energy will be used during a single-pass harvest, therefore the total energy value of the resulting ethanol would be higher, Birrell explains.

Also, the system allows farmers to control the amount of material left on the ground for environmental benefits, he says.

For three years, researchers have been working on creating attachments that can be used on existing combines ”” costing farmers $10,000-$15,000 instead of more than $100,000 for a separate stover combine.

”The goal was to create something that wouldn’t be a large additional cost and to get its field capacity up to 80 percent of normal,” Birrell says.

This fall’s test showed the system harvested about 50 percent of the stover at normal speeds.

”One of the benefits is it allows farmers market corn and corn stover separately,” he says.

When it comes to transportation, Birrell says corn stover density is too light to transport efficiently. In that case, he says researchers are looking into transporting a mixture of corn kernels and stover, where it would be separated at a local facility.

Even with the addition of stover in the ethanol mixture, Birrell says processing plants likely will use both materials for biofuel production

In the end, the processing facility most likely will determine the preferred method of harvest, storage and possibly the hybrid planted, he says.

Processors that use a thermo-chemical conversion would prefer drier biomass, but biochemical processors may prefer stover with higher moisture content, Anex says.

”There are a lot of ways to (harvest, handle and deliver biomass). It will be driven by two things: the facility that will buy it, and the other is the region,” he says.

Drier regions in Nebraska may have biomass-ethanol processors that prefer dry deliveries. Corn dries down more readily in this region, and producers may choose to harvest stover after grain, allowing it to dry in the fields.

But, in areas such as Eastern Iowa where the climate is wetter, processors may be prepared to dry stover to optimal levels on site. Farmers then would use a single-pass harvest and deliver to facilities wet, he says.

Anex foresees the transition to corn stover ethanol as only the beginning for biomass. Other small grains and grasses have even greater biomass energy potential, he notes.

He says farmers may end up harvesting corn for feed and biomass energy in fall, followed by planting small grains for harvest in the spring.

The crop cover during winter and early spring is ”dramatically better for the environment,” Anex says and could be a great source for ethanol.

He sees this type of system as a way to get the most out the land for energy production.

”We have had large success with the corn grain ethanol industry, and we are starting to have a cellulosic ethanol industry that will be based on corn stover,” Anex says.

”Once you have that conversion, there are a whole range of other forms of biomass that may be advantageous because they are more economically and environmentally sustainable.”