Harvesting Cellulosic Ethanol

Peter Hemken, head of DuPont Bio-Based Materials, discusses the difficulty of collecting crops for the fuel.

Chemical giant DuPont said Friday it will give Iowa State University $1 million for a research facility that focuses on how farmers can grow, harvest and store biomass needed to make cellulosic ethanol.

The news comes after BP invested $500 million in biofuels research led by the University of California at Berkeley in February and cellulosic-ethanol startup Mascoma teamed up with the University of Tennessee to build a cellulosic-ethanol biorefinery Wednesday.

Cellulosic ethanol is made from nonfood biomass like switchgrass, wood chips and corn cobs. Companies developing alternative fuel haven't yet been able to produce it on a mass scale, or at an affordable price.

But a combination of government backing and heavy venture-capital investment has pushed the technology closer to large-scale production (see Ethanol's Growing Pains and Biofuels Get Financing Downpour). And projects, like the one DuPont is supporting, will help ensure the infrastructure is in place to get the biomass to the biorefinery.

Greentech Media spoke with Peter Hemken, a vice president at DuPont Bio-Based Materials, to get his take on farm-based challenges to making cellulosic ethanol.

These comments come from at sit-down with Hemken at the Fuel Ethanol Workshop in St. Louis in June.

Q: What's so difficult about harvesting biomass waste?

A: A lot of farmers I talk to kind of scratch their head and say, "This is a pretty good idea. But how am I going to collect this?"

If you want to make ethanol out of corn stover, how does one collect the stocks and leaves? Today the farmer leaves them in the field and just takes the grain out.

And then one needs to figure out how to store the cellulosic biomass. Do you bail it and stack it on the ground with a tarp on it, or what?

Q: When it comes to harvesting biomass, what feedstock should we focus on first?

A: Cobs, that's probably the place to start. They are a little easier to collect.

Q: What potential machinery do farmers have to gather biomass, like cobs?

A: Years ago farmers use to pick the whole ear, husk it and the corn picker would toss the whole ear into the wagon. … Farmers would have a pile of cobs there to get rid of.

I don't think we'll go back to that process, but maybe the combines of the future will collect cobs as well as grain as they're going through the field. And then you dump cobs into one wagon, dump grain into another wagon, or something like that.

Q: Could cob collection become so good it damages the soil?

A: I know a number of universities and other organizations are looking at this. You want to leave some of the leaves and stocks on the field in order to help manage erosion control as well as to provide some nutrients back into the soil. Based on the studies I've seen so far, it looks like you want to leave at least half of it.

Q: When do you think celluosic ethanol will finally come into its own?

A: I think we are probably three years away from the first commercial-scale plants.