Initial momentum for the idea has faded, however, since the economic downturn, and even though some projects are receiving U.S. DOE funding, little progress has been made, and some of those projects have been modified or have even ceased to exist. An explosion of projects to develop stand-alone biomass power plant proposals across the U.S. has some pulp and paper mills and industry/environmental groups speculating that competition for materials will become stiff, prices will rise and resource sustainability may be a problem.
Instead of focusing on co-locating biorefineries at paper mills for added value, many who are still pursuing the concept are emphasizing the benefits of the pre-existing infrastructure, convenient location and trained employees of recently decommissioned mills—which may or may not continue to make paper, but either way serve as a perfect location for fuel, power and chemical production.
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A Mill’s Real Value
“The biorefinery co-located at a paper mill concept assumes there are waste materials from the paper process that are currently unused and suitable for conversion to fuel, chemicals, steam or electric power,” says Kris Plamann, business development manager for Kaukauna, Wis.-based Baisch Engineering, which serves the pulp and paper, biofuels and biomass industries. “Unfortunately, the modern paper mill is quite adept at recycling and waste utilization. Bark and waste wood are burned in the bark boiler to make steam and electricity. Waste paper (referred to by the industry as broke) is reused to make new paper; lignin and part of the hemicellulose is dissolved and burned in the recovery boiler, again making steam and electricity and recovering valuable chemicals to recycle in the pulping process.”
The capital expenditure for a co-located biorefinery is sometimes dependent on the sale of steam to the biorefinery, Plamann says. If the paper mill shuts down, a significant part of the justification for the biorefinery is no longer viable and the project fails. That doesn’t mean that the concept of locating a biorefinery at the site of a paper mills is a flawed concept, however. “A paper mill site might be just about perfect as the right location for a biorefinery—after the mill has shut down,” Plamann points out. “Don’t think co-located biorefinery; think ready-made biorefinery site.”
Plamann says the real value of the mill isn’t combining the biorefinery with the paper mill, or even producing fuel such as ethanol. “The value is in having power, rail, highways, wastewaster treatment, steam, compressed air, space in the wood yard, trained employees, and everything else already there,” she says. “It may well be that the most valuable site is one where the mill has just recently shut down.”
Gary Bosar, Baisch project manager, agrees. “Frankly, this [concept] hasn’t been pushed hard enough,” he says. “The biggest advantage that mills have is the infrastructure that already exists.”
At the same time, the idea of producing fuel for added value shouldn’t be discounted, and some projects have shifted toward fuels other than ethanol, such as green diesel. “Specialty mills often face the problem of reusing colored broke, especially deep colors,” Plamann says. “Broke is 80 percent pure cellulosic material, and when used as an alternate fuel feedstock, it would probably result in nearly 100 percent yields.”
Everyone is concentrating on wood as the feedstock, because that’s what a mill uses, Plamann says. “However, if we think in terms of cheaper alternatives such as waste paper, paper mill sludge, corn stover, switchgrass and tree trimmings, and use the existing mill facilities to handle them, we could eliminate lots of costs and make them competitive.”
Exploring alternative feedstocks will be essential for some projects to get a green light, especially the ones located in areas where other projects require woody biomass. In some states such as Wisconsin—which is the No.1 papermaking state in the U.S.—competition for woody biomass may be heating up.
Competitor or Companion?
While residents in communities where a large chunk of the population work at failing mills might view biorefineries as an economic savior, when built separately, some paper industry groups view them as a nuisance.
Recently, North American papermaker Domtar Corp. announced it may host We Energies’ $250 million cogeneration biomass power plant at its paper mill in Rothschild, Wis. We Energies estimates the biomass power plant would require approximately 500,000 tons of material per year, consisting of recycled mill waste (bark and sludge residues) from the papermaking process, and waste wood from area forest operations and saw mills.
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