This past spring, Georgia-Pacific, the paper-manufacturing giant that brings us such familiar products as Quilted Northern toilet paper, closed down its paper mill in Old Town, Maine — laying off hundreds of workers and dealing a blow to the local economy. With cheaper sources of wood pulp flooding in from countries like Brazil and New Zealand, many American pulp and paper mills are just not making enough money to stay open.
Hemant Pendse, chair of the University of Maine’s Department of Chemical and Biological Engineering, says that there’s a solution – turn mills from simple pulp factories into complete “forest biorefineries” that convert current waste products into valuable ethanol. This would kill several birds with one stone: increase profits, provide a desperately needed source of fuel, and be better for the environment.
According to Pendse, the way wood is being processed now is far from efficient. “Only half of it is actually coming out as pulp. Half of it is either burned or sent to the landfill. And that’s not the way things should be done,” he explains.
He says instead, unused wood should be money in the tank. With funding from the National Science Foundation, the University of Maine is creating a way to refine forest biomass into ethanol fuel.
Wood has three essential components – cellulose, lignin, and hemicellulose. Cellulose makes up the majority and contains valuable fibers that we turn into paper. Lignin releases a lot of energy when burned as fuel, and hemicellulose is usually just treated as a waste product. As Pendse explains though, valuable ethanol can be fermented from the sugars in hemicellulose. Until now, the problem has been that there wasn’t an efficient enough way to purify it from the other wood chemicals that remain after pulping. The UMaine group’s solution — remove the hemicellulose before the pulping process in a clean, water-based way.
Pendse, who heads up the project, says another bonus is that removing the hemicellulose doesn’t affect the quality of wood fiber. That means wood and paper companies could add profits by extracting it from wood before making their usual products.
“There is ethanol on the market that’s already blended with gasoline. That fuel ethanol right now is being produced in the Midwest from corn kernels,” says Pendse. But there are problems with making ethanol from corn, even besides the obvious one that we need it as food. The process of converting corn into ethanol is simply inefficient – you barely get any more energy out as ethanol than you put in as fertilizer, farm work, and the actual conversion process.
“Realistically, you really cannot grow sufficient amounts of corn kernels to meet the demand of the fuel that we would be able to use right now in the US in the next few years,” Pendse says.
Pendse, says it takes so much less energy to grow trees than corn, that ethanol won’t be economically viable unless wood is added to the equation.
“We’re talking about it being 500 percent or 700 percent more energy that you can get as a renewable transportation fuel,” says Pendse. Wood — which Pendse points out is as important a crop in forested states as food crops are in agricultural areas — also has basic advantages as a crop. Trees are abundant and available year-round, and they don’t require fertilizer.
Pendse says that applying these new principles to the way wood is currently processed could prevent mill closings like that of the Old Town Mill.
“While preserving existing operations we can add on additional product lines which will be the fuel ethanol and that help us not only get fuel ethanol but save the jobs that are already there in this industry,” says Pendse.
In the near future, Pendse says they can also use wood to make the chemicals that go into production of plastics instead of relying on foreign petroleum for those as well.
The group’s research is published in Pulp and Paper Canada, in press 2006; Technical Association of the Pulp & Paper Industry (Tappi) Journal, 2004 and funded by the National Science Foundation (NSF).