FOREST PRODUCTS EQUIPMENT
The Future of Wood and Wood Waste
Low-grade chips and waste wood serve as fuel to power a biomass boiler.
Photos by Brett McLeod, unless otherwise noted.
If wealth promotes waste, then tough times might just be the ticket to resourcefulness. As a professor of forest economics, I often describe efficiency to my students as "the absence of waste." Historically, the forest products industry didn't exactly practice efficiency in the context of minimizing waste. Demand for hemlock bark from tanneries throughout the 19th and early 20th centuries left millions of board feet of logs rotting after the valuable bark was peeled away. Accounts from early New England logging camps describe only taking the bottom log out of trees to avoid dealing with the hassle of limbs and smaller logs. However, times have changed, and as economic and ecological constraints rub closer together, innovation will be the new imperative.
The future of utilizing wood waste is likely to operate in both low-tech and high-tech spheres. Many of the low-tech approaches to utilizing wood waste will sound familiar to some readers, though their application still tends to be localized, with significant growth potential. High-tech solutions, on the other hand, will likely rely on emerging bioenergy markets and engineered wood products.
Somewhat paradoxically, it has been the small mills and wood processing facilities that have responded to wood waste by pioneering new and innovative markets - often out of necessity. One such small mill is Ward Lumber, located in Jay, N.Y. Ward Lumber focuses on white pine products, and it prides itself on 100 percent utilization of wood. The bark is removed, ground and sold in bulk for landscaping. Sawdust is sold as an alternative to straw bedding, and it has gained popularity as a low-cost alternative to straw. In addition to sawdust, planer shavings are used as a livestock bedding material and increasingly as a clean, cost-effective cage lining material for research animals (think mice and birds). Debarked slab wood is sold to International Paper for pulp production. Finally, any remaining residues (e.g., wood chips too big or too small) are used in the dry kilns, saving the equivalent of 225,000 gallons of heating fuel per year.
The substitution of woody biofuels for heating oil is perhaps the greatest change in recent years, and also represents the greatest opportunity for innovative uses of low-grade wood in the future. Many had predicted that woody biofuels, particularly at the residential level, would simply be a fad, as local ordinances imposed heavy regulation on outdoor wood boilers. However, cleaner-burning gasification technology has largely squelched opposition, especially given that the primary alternative, oil, comes with its own long list of external costs imposed on society (think subsidies, human health, the release of stored carbon, etc.).
Living in rural America, it is hard not to question the logic of having giant fuel trucks literally driving through forests of potential bioenergy to deliver petroleum that traveled 8,000 miles by barge and truck. Most estimates put the "real" cost of petroleum fuel around $15 per gallon once the subsidy, health and environmental costs are incorporated.
This biomass boiler is used to heat a school in Vermont.
Perhaps a more practical approach would be to match local fuel sources with local energy demand? In the Northeast, this would mean treating our forests not as factories and warehouses for consumption on the global market, but as local "woodbaskets" capable of meeting local heat and energy needs for both households and municipal buildings, like schools. Such a strategy is also well-aligned with silvicultural objectives that aim to improve forest health by reversing the historical paradigm of high-grading to a new paradigm of low-grading forests to remove suppressed and genetically inferior trees.
While the "woodbasket" concept represents a potential use for addressing local heat and energy needs, woody biofuels can also include liquid fuel replacements for gasoline. The use of corn and other foodstuffs has largely been controversial because it means trading productive agricultural land (and food!) for starch-based ethanol from crops. Woody, cellulosic ethanol may, in part, address this issue because a variety of tree species, including willow and aspen, are able to grow on marginal soils not suited to the cultivation of food crops. In addition to cultivating biofuels, a variety of waste products can also be used, including sawdust, bark, wood chips and even municipal solid waste.
Chips are stored in a hopper and moved into the wood boiler using an auger.
However, despite the promise of cellulosic ethanol derived from low-grade and waste materials, several formidable barriers remain. The first is that few large-scale cellulosic ethanol plants exist. Smaller producers that have attempted to scale up have failed due to limited private sector investing. Many investors note that while wood waste and cellulosic feedstock are inexpensive, the enzymes needed to produce the ethanol are often cost-prohibitive (about $3 in enzymes to make 1 gallon of fuel).
In terms of manufactured wood products used in construction, the trend is to utilize all wood waste - an efficiency goal that is only made possible due to recent advances in wood adhesive technology. The earliest use of wood adhesives was to bind rare wood species as decorative veneers by early Egyptians. These adhesives were protein adhesives derived from natural sources. Today, synthetic binder adhesives are the basis of virtually all wood products derived from wood waste, including particleboard, oriented strand board and medium-density fiberboard. Again, thanks to adhesive technology, more sophisticated engineered wood products such as wooden I-joists and engineered trusses are replacing dimensional lumber.
A practical approach might be to match local fuel sources with local energy demand. In the Northeast, this would mean treating our forests as local "woodbaskets" capable of meeting local heat and energy needs.
While making bigger products with smaller pieces is a fairly easy future to envision for wood waste, there are other factors that make the future of forestry, along with its products and waste, even harder to predict. At some point, one must ask: Where will the wood come from? Large tracts of forestland, particularly in the Northeast, have been broken up into parcels and fragmented. This fragmentation of land ultimately leads to fragmentation of purpose. A 100-acre woodlot quickly becomes 100 1-acre lots. In such cases, not only the wood, but also the associated benefits, ranging from wildlife to water quality, are compromised.
Finally, it is worth noting that predicting the future of anything, especially a volatile industry, is an imperfect art at best. Peering through forest product journals written over the last half-century highlights this fact. Some of the more noteworthy false predictions include the "timber famine" of the 1950s and 1960s, as well as the production gains in Southern pine plantations that failed to come to fruition. Then there is the "paperless society" that, in reality, became the "print everything society."
A 100-acre woodlot quickly becomes 100 1-acre lots. In such cases, not only the wood, but also the associated benefits, ranging from wildlife to water quality, are compromised.
Photo courtesy of Andreas Krappweis/sxc.hu.
However, past is prologue and the future of this industry, including wood waste and low-grade materials, is likely to be a function of being able to see opportunity where others only see waste.
Brett McLeod is an associate professor of forestry and natural resources at Paul Smith's College, located in the Adirondacks of northern New York.