Improving the Journey of Biomass from Sunlight to the Pump
Published: Sep. 21, 2009
URBANA - A lot has to happen to a plant from the time it first captures sunlight in a field to being dispensed as fuel at the pump. For corn-to-ethanol, that path is fairly predictable, but for energy crops such as Miscanthus or switchgrass the journey is still through somewhat uncharted territory.
"There's not as much information on energy crops as we have on corn and soybeans and wheat and cotton. So we have to build on those past successes and learn," said University of Illinois agricultural engineer K.C. Ting.
"Energy crops like Miscanthus cut differently; a corn harvester cannot be used to harvest energy crops. Maybe the closest comparison is hay, but that's not a perfect comparison either."
Ting is leading a team of Illinois researchers in a program funded by the energy firm BP in the Energy Biosciences Institute (EBI) — a partnership between the University of California-Berkeley, the Lawrence Berkeley National laboratory, and the University of Illinois.
The program is called Engineering Solutions for Biomass Feedstock Production. A paper about the program was published in a 2009 issue of Resource, a publication of the American Society of Agricultural Engineers.
"We are studying the issues and logistics involved in getting biomass from field production to the gate of the biorefinery. When the truck delivers the biomass to the refinery, that's when our job as agricultural engineers ends," Ting said.
The program breaks down the journey into five tasks -- pre-harvest crop monitoring, harvesting, transportation, storage, and the overall analysis of information.
Every step of the way, there are new challenges and questions unique to energy crops.
"In the pre-harvest crop monitoring, we look at how precision agriculture, remote sensing, can be used to help growers understand how to manage these new crops," Ting said. "Even harvesting has several steps: you have to detach it, you have to gather it, collect it, and resize it. Then you may have to either bale it or compact it. You have to load and unload many times from the field to the biorefinery. And in between you may need to store it. Sometimes the harvest window is small, but biorefineries need a year-long supply of constant high-quantity material. We have to find ways to keep it for a whole year in storage."
Researchers at the University of Illinois use a variety of techniques for pre-harvest crop monitoring. A tower over a hundred of feet high with a multi-spectral camera watches over four nine-acre plots to study the health of the crop, a small unmanned helicopter can fly over crops to acquire images, and a cube-shaped frame with sensors is moved slowly across the crops. "Using these precision agriculture methods, we can help growers monitor crop growth, detect problem areas, and suggest what they need to do. With cotton, if you take an image, you can tell whether it is suffering from drought or insect or disease. But energy crops are so new, there's minimum data," said Ting.
At the refinery end of the chain, Ting said there's more information that is needed. "Can they just accept the whole bale? Unload it at the gate? We need to have a seamless connection."
Like passing a baton in a foot race, Ting explained the need for an interface between the "runners" in the energy crop value chain. The program is examining those interfaces that occur along the way — gathering data that will help find solutions and improve the overall process.
"You can have the best harvesting, storage, and transportation, but how do you link them? Global optimization is as important as local optimization. A lot of research we do is local optimization — trying to optimize a particular task locally, but there's no guarantee that a locally optimized task will give you the best performance overall. Some may be locally optimizing by transferring problems to another stage. 'I don't want to deal with it. Someone else has to deal with it.' The whole system starts to have bottlenecks. Our program looks at the whole system."
Ting used the analogy of constructing a building. "You have lighting, you have air conditioning, you have carpeting. Someone has to come up with an overall blueprint and then resolve the differences. And to enable interfaces to happen seamlessly, you need to identify the information you need. Without information, no one can do anything.
"Certainly we don't want to recreate the wheel. There are already established methodologies and science in handling other kinds of biomass, mostly grains and cottons," he said. "What we are doing is using the same methodology and modifying it to conduct new experiments on energy crops. For example, there's a lot of information on how to store corn and hay. You have to deal with sugarcane within 72 hours. There's a lot of science on how to study the preservation of crops, so we start with that."
Ting said that technologically, it's all doable today. "But it's very expensive and non-optimal. The challenge is how can we do it with the least cost, labor, energy consumption, and greenhouse gases while delivering the highest-quality biomass?
"Unlike research projects, programs are more a theme type of research on a larger scale, for a longer time, and hopefully will have a larger impact," Ting said. "When this kind of important theme is funded, it's expected that it would take ten years to complete, but it's funded in a three year rolling fashion. It's our job to continue to contribute and keep it relevant."
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