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New composites, nanocellulose coatings, liquid fuels are on the horizon
By Joe Rankin
Forests for Maine’s Future Writer
Dwane Hutto is obviously enjoying himself. He has just described a fairly complicated chemical process that started with ground up trees and produced a dark liquid in a vial that he holds high so everyone can see it.
“Guesses what this is?” he asks.
Dwane Hutto shows off a container of “crude oil” made from wood. (Photo: The Rankin File)“Molasses?” someone suggests tentatively.
“Not molasses.” Hutto pauses. “Crude oil. Cool, isn’t it.” Hutto’s voice rises gleefully. He’s project manager for the University of Maine’s Forest Bioproducts Research Institute, but it’s clear he still revels in science’s ability to conjure up neat stuff. Hutto says the liquid essentially contains a mixture of biodiesel, gasoline and jet fuel. And it started out as cellulose from a tree. Cellulose is a basic component of all plants.
It used to be that forest products were pretty basic: firewood, lumber, paper. But the forest products of the future are just as likely to come in a 55-gallon drum, or turn up in a coating made of nanocellulose, or be extruded with plastic to form complex shapes.
It’s a brave new world out there.
The dozen or so members of our group are visiting three sites where that future is being written, the FBRI in Old Town, the University of Maine’s Advanced Engineered Wood Composites Center, and Corinth Wood Pellets. The day-long “Future of Forest Products in Maine Tour” is sponsored by The Nature Conservancy’s Maine Chapter, the Forest Society of Maine, and the Maine Tree Foundation.
First stop is the wood composites center. There staff, faculty and students perform stress testing on lumber and beams, do research to create better composites of wood strands and high-tech adhesives, and research new hybrids of wood and plastics, materials that can be stronger, more weather resistant than wood itself.
Prof. Stephen Shaler explains the ins and outs of creating wood “strands” to make composites. (Photo: The Rankin File)They’re also researching how to use nanocellulose to make stronger and lighter products. In a separate part of the building is the center’s wind testing facility, dedicated to testing the humongous propeller blades – up to 230 feet long – to ensure that they’ll stand up to the stresses of the wind’s they’re designed to harness.
Researchers work on their own projects, they contract to do research, and companies with ideas come here to use the Center’s equipment to see if their bench-top research and prototypes can be successfully scaled up, or simply because they need access to the specialized equipment. It’s a busy place, with 35 staff, 12 faculty members and dozens of graduate and undergraduate students working there.
Everyone is familiar with wood composite materials. Plywood — thin sheets of wood glued together under pressure — is a composite, and it’s been around a long time. Newer, but still old hat, is oriented strand board, commonly known as OSB. Particle board is another. But researchers are always looking at ways to improve on the idea, said Stephen M. Shaler, a University of Maine professor of wood science and an associate director of the Center.
Lumber in its original form is great, especially if it’s free of defects, said Shaler. But sometimes designs call for bigger beams than are available. Or flat panels with special properties. And that’s where composites come in. “That’s the real key with composite materials,” said Shaler. “You get rid of the defects or make them small and disperse them so the material is more uniform and the variability is less.”
The Center will work with any manufacturer to improve the composite process, by trying a different adhesive or additive. For one client they undertook to research what happens when you extract certain sugars from the wood, using heat. The process makes the wood less dense, but it also makes it more brittle, Shaler said.
Working with the U.S. military, the center designed a blast-resistant modular building that could be used by
Checking out the Wood Composites Center’s demonstration blast resistant building. (Photo: The Rankin File)troops at semi-permanent bases. Additional composite ballistic panels provide protection from bullets and shrapnel as well. Larry Parent, the Center’s assistant director, said that key to the structure’s performance in blast tests are standard 2 by 4s edged with a composite tape and wrapped in a non-woven tape. The edgings and wrappings add strength, but also reduce splintering. Splinters can be lethal spears in a blast.
The building can be quickly erected using standard carpentry tools. It might not be the Ritz, but for troops in the field it would provide far more protection than bare tents. “If you’re going to be in an area for three months or so you’d probably be housed in a tent,” Parent said. “But if you’re building a temporary base where you’re going to be for three to five years, what you’d like is to build buildings, and that’s what we’ve designed.”
Prototypes were tested with live mortar rounds, Parent told the group. After three generations in development, the concept is ready for market. Parent said the university is looking for a company to take it there. The university would get some small royalties out of it. The building wouldn’t just be a boon for troops in the field, but could be used in areas that are prone to hurricanes or earthquakes. Or perhaps refugee camps.
The Center is well-known for its “bridge in a backpack” technology. It uses rigid composite arch tubes as the foundation for a concrete overstructure. The tubes are lighter, stronger and last longer than concrete girders. They can be easily erected without the heavy equipment required to build regular bridges. And fast. Some bridges built using the technology can be put up in two weeks. The “bridge in a backpack” technology is licensed to Advanced Infrastructure Technologies. So far 12 of the bridges have been built, including seven in Maine. Another half dozen are in the design stage. Parent said the maximum arch now possible is about 70 feet, but “we’re working on something bigger than that.”
Prof. Stephen Shaler (yellow helmet) explains extruded composites. (Photo: The Rankin File)The Center still does testing of regular lumber. Shaler told the group that the center will begin testing Norway spruce lumber soon for structural uses. And the Center recently did stress tests on black locust lumber that’s now being used to build a 400-foot pedestrian bridge underneath New York City’s Brooklyn Bridge as part of a park project.
At the other end of the wood spectrum, the Center is researching potential products and uses of nanocellulose, tiny fibers of cellulose in the nanometer range. That’s tiny. A nanometer is a billionth of a meter. When you’re talking nano-cellulose you’re talking particles up to about 100 nanometers.
“Maine is a real leader in this,” said Shaler. “We have a large project with the U.S. Forest Service where we’re using mechanical and enzymatic means to break the cellulose down.” The Center is not only experimenting with the process, but analyzing the strength, conductivity and other charcteristics of such small scale materials.
At the Advanced Engineered Wood Composites Center they’re mainly concerned with combining wood with other things, such as plastics, to make products.
At the Technology Research Center at Old Town Fuel and Fiber, a part of UM’s Forest Bioproducts Research Institute, they concentrate on breaking down wood into its chemical components and using that to make other products.
“Wood products – pulp and paper – have been around for a long time. Forest bioproducts is the next generation of products, where they can use wood in different ways and get new revenue streams,” said Hemant Pendse, the chairman of UM’s Department of Chemistry and Biological Engineering.
The Technology Center has been a leader in developing wood-derived biofuels, sort of the forestry version of ethanol, which is currently produced from corn grown in the midwestern U.S.
The basic process involves a extracting the sugars from wood chips destined to be turned into pulp, fermenting and distilling the extract, Pendse told the tour group. The process leaves the wood fiber untouched and usable.
A bridge in a backpack under construction. (Photo: University of Maine)Everett Deschenes, the Old Town mill’s manager for fiber and logistics, said the mill already has a pilot plant up and running and “we’re looking at moving that forward in the near future.” Biofuels from wood, he said, could provide a second career for aging or underutilized pulp mills around the world that can be put to work producing it.
“We’re very confident that we can build a demonstration plant, we’re very confident we can build it onto someone else’s digester and produce fuel. Our next hurdle is marketing. We need to compete with cane sugars and other agricultural sugars,” and with the cheap natural gas now on the market, he said.
Meanwhile, the Center is continuing biofuels research along a different line, the one Dwane Hutto was touting with his molasses-colored fuel blend.
In that process, Hutto explained, the cellulose is actually broken down and by a rather complex series of chemical processes ends up being something you could put in your lawnmower. That’s the big picture. For the person who last picked up a chemistry book in high school, following Hutto’s step-by-step explanation is a little daunting. You can get lost fairly easily and end up saying, “Huh?” Suffice it to say he got people’s attention when he told them what the molasses-colored liquid was.
“Wood is nature’s best engineering material. It’s structurally strong,” said Pendse. “We should use wood as wood, but if you can’t do that, use the fiber. If you can’t use it as fiber, go out there and get the chemicals from it. If you can’t use the chemicals, then I would burn it. But to me burning wood is the last on my list.”
In addition to biofuels, the Technology Center, like the wood composites lab, is also looking at nano-cellulose. Hutto showed off different forms of nanocellulose. Oven-dried, he said, it actually turns into a glass which can be formed and milled or pressed into thin sheets “that’s got some really different characteristics to it.”
You can also produce nanocellulose from lignins extracted from wood chips, said Hutto. The lignins are the glues holding the wood fibers together. Normally they would simply be burned. But combined with water, sprayed on a rotating drum supercooled with liquid nitrogen, they form nanocellulose, Hutto said.
An electron microscope photo of nanocomposite fibers. (Photo: University of Maine)“We haven’t figured out how to use it yet. A small sample is about a week’s worth of production,” said Hutto. But “rather than having a value four to five cents a pound as lignin it could be worth $300 to $1,000 a pound as a nano-carbon fiber. “We think it can be used as a conducting material for high-strength polymers,” because it exhibits almost no resistance to electric current or heat, Hutto said.
Like the Advanced Engineered Wood Composites Center, the Forest Bioproducts Research Institute’s Technology Research Center, which opened only last summer, does its own research, but also opens its facilities to other researchers and companies engaged in chasing the forest bioproducts dream.
“This new technology center allows appropriate private sector folks to come here with their own ideas to work with university researchers to take their own work beyond the bench scale, to try something on a reasonable scale and collect the data and take the samples back home, then work on their own applications so they’ll have a competitive edge. That’s the way you create new jobs,” said Pendse. “We already have several small business technology companies working with us.”
While the Technology Research Center at Old Town Fuel and Fiber is working on the forest-derived fuels of the future, Corinth Wood Pellets, our third stop on the tour, is producing the forest-derived fuel of today.
The pellet mill was the first in the state, and has the capacity to punch out up to 50,000 tons a year, Plant Manager Randy Irish told the group as he led us on a tour of the grounds. Wood pellets as fuel came into their own in the late 1990s and in 2005 use, and production, started to surge as the price of fossil fuels spiked. Wood pellets are very popular as a heating source, and use is expected to double in the next five years, according to a report by the Biomass Energy Resource Center.
Corinth Wood Pellet Mill against the sky. (Photo: The Rankin File)Irish said wood chips are screened, ground, dried, screened again, ground again, and then run through a huge extruder that converts what is essentially sawdust into uniform pellets. The pellets, still hot, are held together by the original lignins, but need to be cooled before being bagged or the residual heat would turn them back to sawdust.
Irish said the dryers, crucial to the process, are run with waste from the pellet-making process, making it extremely cost effective. One interesting thing: part of the process includes rounding the sharp edges of the pellet to make it flow through the stove’s feed auger better.
“It creates a nice, hard, durable pellet,” said Irish.
Durable, as long as it’s kept dry. Some retailers have found, to their chagrin, that they can’t leave bags of pellets sitting outside in the rain, even if they are bagged in plastic. The pellets are “basically compressed sawdust looking for moisture,” Irish said. If the contents get wet, what you can end up with is wet sawdust.
Wood fuel pellets, still warm. (Photo: The Rankin File)The tour got good reviews.
Tour participant David Barber reminded Sherry Huber of the Maine TREE Foundation that she “had told me many times that you can make anything out of a tree, but to see it is really interesting. I was impressed. It’s kind of neat.”
Tom Rumpf of The Nature Conservancy said seeing the possibilities is exciting. “It’s great to see this type of R & D taking place in Maine. We have the largest intact forest in the country and this is the way we’re going to keep it intact.. I hope that everyone is successful. It’s the only way we’re going to be competitive in the forest products industry.”
Joe Rankin is a beekeeper and writer on forestry topics. He lives in New Sharon.
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