He realized, for instance, that an economically viable business that makes biomass fuel on a national scale would need to operate on a local basis to cut transportation costs. It would want to use olive pits and almond waste in California, cotton and tobacco waste in the South, corn in the Midwest, beets in North Dakota, and so on. It wouldn’t want to carry the olive pits from California to Minnesota to process them into pellets or biocrude.
Walker’s plans for Bixby Energy Systems ultimately call for plants around the country, and perhaps the world, that will take in all manner of local materials by truck and convert them to pellets—or to biocrude, which would be further refined at other plants. But even a processing plant every hundred miles doesn’t fully lick the biomass transportation problem, which is one reason Walker loves pyrolysis.
Consider wheat straw, he says. “A great fuel—9,000 BTUs per pound. But it’s so light, so non-dense, that if you fill a 40-foot trailer with it and haul it even 50 miles, the freight costs would kill you. It’s like shipping smoke.”
Ah, but Roger Ruan’s pyrolysis process involves what might be described in layperson’s terms as a kind of microwave oven that is perfectly easy to run. Big ones would go into processing plants, but smaller ones could go into farmers’ barns. Says Walker, “You can put that 40-foot trailer of wheat straw into a bin in your barn, add water, flip a switch, and two hours later it becomes 3.5 barrels of biocrude. There is no cheaper way to ship energy than in a liquid state.”
Indeed, he says, if one of Bixby’s trucks is delivering fuel to heat the farmer’s house and outbuildings, “we can pick up [his biocrude] on the way back. Now we’ve got a two-way haul, which makes it even more practical. We take the biocrude back to our plant and refine it into a fuel. And if we’re not making enough money off that, we can subsidize the operation by processing it further and turning it into polymers for plastics or any of 50 different chemicals.”
This is how Bob Walker thinks about alternative energy. Whether his vision for Bixby Energy Systems comes to pass or not, his thinking has gained the ears of people who believe that the planet is more likely to be saved by a good business plan than by good intentions.
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Pyrolysis 101: taking biomass from solids to gases to liquid biocrude. Pyrolysis—the process by which Bixby Energy Systems intends to convert biomass into liquid biocrude fuel—is pretty easy to understand, at least in broad strokes, when Dr. Roger Ruan explains it: “You basically use some kind of energy source”—he’s worked with microwave energy, for one—“to heat up the biomass and convert the solids into gas, into volatile components. And then some of these volatile components can be condensed to become bio-oil, and the others that cannot be condensed become syngas”—a mix of hydrogen, carbon monoxide, and sometimes methane—“that you can use to generate electricity or burn to generate heat.” He says even at 400 to 600 degrees Celsius, as much as one-fourth of the raw biomass material (minerals and other components) remains in solid form, “char” that has its own uses, in fertilizer, for instance. Ruan, a professor in the University of Minnesota’s Department of Bioproducts and Biosystems Engineering and director of the U’s Center for Biorefining, makes something else clear: Pyrolysis (a heat-based process)—like the hydrolysis and fermentation (water- and enzyme-based) process used to produce ethanol, or the various gasification and bacterial-digestion processes that can also be used to convert biomass—is just one piece of a biorefining approach to renewable energy that needs to be advanced as a whole. Each process has its advantages and limitations in terms of efficiency and costs, and each yields products that complement each other. Biocrude, for instance, needs to be stabilized with an alcohol like methanol or ethanol to become practical for use as a gas-turbine or home-heating fuel. Ruan will report on his biorefining research, including microwave-assisted pyrolysis, at a May 13–15 conference at the university. The program will focus on applications and commercialization of renewable energy research being done collaboratively by the University of Minnesota and University of Life Sciences at Ås, Norway. Watch for more information to be posted. |
