PROCESSING AND MARKETS
WOOD RESIDUALS FN
I D BG
I USES
N
I SMALL PE
ICES
T
HE PORK industry always brags
that they use everything but the
squeal. Soon, the lumber industry
may be starting to brag that they
are using everything but
t!le leaves.
While the industryisn’t there yet, it
has come a long way from the days
when most of the residuals that
Carrie from its
mills either were consumed in teepee burners or dumped somewhere.
In 1993, more than 110 millioc dry tons
of wood residue were generatedby the primary wood processing plants in the United
States, Of that total, about 25 percent is
bark, 25 percent is sawdust and 50 percent
are trimmings, such as slabs and end cuts.
It is estimated that about 95 percent of
those residuals are putt o some use such as
the production of fiber products (i.e., paper,
particleboard, etc.), fuel o r some other
wood-based product.What remainsis about
1.5 million tons of bark and4.7 million tons
of trimmings and sawdust.
One thing that hasled the wood industry
to utilize so much of its residue isthat it’s a
volume commodity.During theprocessing of
logs into lumber, theU.S. Forest Service estimates thatonly about 63 percentof a harvested tree can be converted into a solid
lumber product, like two-by-fours and dimensional stock. That means one third of
the harvestwould be waste if someother use
weren’t found. Obviously, those in the primary wood processing industry have a real
interest in finding ways to use as much of
the logs as possible. The other stimulus is
the dwindling supply of timber that can be
made into plywood and other products.
While folks in forestry talk about allof the
trees planted each year,
it takes along, long
time to produce a tree trunk that can be
turned into a two-by-twelve or a piece of
hardwood worthy of making a piece of furniture. This has led the industry to develop
products that use smaller pieces of wood or
wood fiber, e.g. plywood, oriented strand
board (OSB) and particleboard.
Given that so much residue from the primary wood processing industry is used,one
might conclude that interest in finding additional markets would be limited. However, nothing could be further from the truth.
BIOCYCLE
With a history of
finding economic
uses for leftovers,
the w o o d
industry explores
sustainable
options for
creating higher
value products.
Jim Glenn
Years ago, companies saw theuse - any use
- of residues as a sound,
economic business
practice. Today, many companies are looking to go beyond low value products suchas
mulch, animal bedding and fuel, and market
t o higher value end users.
Additionally, with
so much material from the primary industries already accounted for, consumers of
wood residue are in need of additional supply from sources such as secondary mills
(furniture manufacturers, etc.), as well as
the C&D and MSW streams.
TO MARKET, TO MARKET
Many markets for residuals from primary
mills and other sourcesof wood by-products
have become well established over the
years, as in the pulp and paper industry,
which is by far the largest user of residual
wood. Chips from primary mills, for instance, accounted for more than a quarter
(33 million tons) of the pulpwood consumed
by the pulp and paper industry 1994.
in
Engineered wood -which includes particleboard and medium density fiberboard
(MDF) - as well as hardboard and insulation board, all are made using small fragments ofwood as their principal building
block. Because of this characteristic, engineered wood products aregood candidates t o
use residuals. In fact, of the estimated 11
million tons of fiber consumed by these products in the U S . during 1993, about 90 percent was residue from mills.
Presently, there are about 50 particleboard mills and another 20 MDF plants in
the United States. Combined, these plants
have more than 6,500 million square feet of
capacity (three-quarters-inch basis), 5,000
million square feet of which is particleboard
capacity. There are plans t o add another
1,000 million square feetof capacity, roughly split between the two. Most of these mills
are located in the southern, far west and
Great Lakes states.
At a recent workshop sponsored by the
New York State Energy Research and Development Authority, “Adding Value to
Wood Residue,” Brent English, an industrial specialist with the U.S. Forest Service’s
- part of
Forest Products Laboratory (FPL)
the U.S. Department of Agriculture - notDECEMBER
1996
35
Given that so much
residue from the
primary wood
processing industry
is used, one might
conclude that
interest in finding
additional markets
would be limited.
However, nothing
could befurther
from the truth.
Fuel pellets made from
wood residue are being
marketed for home use
in energy efficient pellet
stoves.
COMPANIES TAKE ADVANTAGE OF
HIGHER ENDUSE PRODUCTS
HILE most wood-based businesses
market much of their own residuals,
many aren’tsatisfied with the return
from low valueproducts such as mulch, animal bedding or boiler fuel. As a result,
some firms aretaking advantage of higher
value markets. One example is the Pallet
Corporation of America(PCA) -a pallet reclaiming company in the Elmira, New York
area- which has been collecting used pallets from a 60 mile radius of its plant then
rebuilding and reselling them since 1992.
Initially, the firm used a tub grinder to process residual lumber generated from its
operation. Not only was that labor intensive, the end product was only good for
boiler fuel or mulch. Withthe help of funds
from the New York State Department of
Economic Development,PCA purchased a
system that allowed it not only to automate
its residuals handling, but also to market
the chim toa local MDF plant.
W
Scraps are conveyed directly from
where the pallets are being reworked to a
slow speed grinder and then into waiting
trailers, explains Jim Sturges of PCA. The
grinder system also is equipped with a
cross belt magnet that removes any tramp
metal contaminants.
Another exampleis a pellet manufacturer who wanted to solve a wood residual
problem. The core business of Hamer Pellet Fuels in Kenova, West Virginia
is lumber.
The firm operates five sawmills, four in
West Virginia and another in Kentucky. Until recently, Hamer sold most of the sawdust it generated to paper mills. Unfortunately, those sales only paid for about half
of the hauling bill. “We were losing about
$100,000 per year,”Jim Hamer says.
In 1990, Hamer began investigating pellet fuels. By 1992, the company started operating two small used mills. “For us, the
first two years were a struggle,” says
Hamer. “We had to get much bigger to
make it profitable.” It recently expanded by
purchasing a larger dryer and is now processing 10 to 12 trailer loads of wood
residue per day. Hamer brings in sawdust
from four of its five mills and purchases
sawdust from three other local mills. h i tially, Hamer marketed pellets through the
same shops that sold the pellet stoves.
While these local stores are still steady
customers, in the last two years larger
building supply stores such as Lowes and
Home Depot, as well as retail outlets such
as Wal Mart, are now the prime movers of
the pellets.
,
percent of the plant’s wood feedstock comes
from pulpwood,with 50 percent coming from
mill residue and the remainder
from pallets,
C & D, and the like.And all of this material
comes from within 100 miles of the plant.
One of the early users of urban wood in
ed that “it’s best if products ‘pull’ the wood.”
That’s certainly what happened in thecase particleboard was Willamette Industries. In
of particleboard and MDF. While demand the early199Os,Northwestern timber shortfor them was stimulated
by a decreased sup- ages caused Willamette to turn to urban
ply of suitable solid woodproducts, in many wood to helpsupply its Eugene, Oregon mill.
instances economics has madewood residu- In 1995, the Eugene plant used more than
60,000 tons of urban wood to manufacture
als the feedstock of choice.
Take the case of Allegheny Particleboard particleboard and MDF. Willamette found
LP in Kane, Pennsylvania. Speaking at the that perhaps thebiggest challenge to using
Adding Value Workshop, Chris Works, the urban wood was the presence of contamiplant’s operations manager, explained that nants. Metal,glass and rocks wreak havoc on
when the facility was built seven years ago, machinery a t both the particleboard mill and
it was designed to consume pulpwood from customers’ plants. Additionally, because its
hardwood species, which at the time had a customers manufacture with such tight
relatively low value. About four years ago, it specifications, even small quantitiesof hard
began to take woodchips and sawdust from or soft contaminants such as rubberor plasregional sawmillsand recently has startedto tic cause defects in thefinished product.
Jeff Fehrs of C.T. Donovan Associates in
add urban wood to the mix. Gravitation toward thesefeedstocks is fueled by economics, Burlington, Vermont, organizers of the
according to Works. Today, only about 35 Adding Value Workshop, notesthat thebest
36
BIOCYCLE
DECEMBER
1996
way to insure that urban
wood is acceptable
t o end users (such as particleboard and
MDF manufacturers) is source separation.
Clean, untreated wood from pallets and dimensional lumber isn’t likelyt o contain potential contaminants, he says.
MORE MARKETS, HIGHER VALUE?
Even though particleboard didn’t begin
to
exhibit significant commercialization until
the 1960s and MDF wasn’t introduced until
then, today both are well established products and, as describedabove, both are large
sinks for wood residuals. There are,however, otherproducts that offer the promise of a
higher value for the residue or the promise
of markets for residues that don’t meet
stringent specifications.
One of the most encouraging areas is using wood in other types of composites. For
instance, wood has been combined with cement to produce materials broadly classed
as cement-bonded wood composites for more
than 60 years. These composites largely
have been used to improve the acoustics and
insulating properties of the cement, where
strength isn’t a principal concern. Highway
sound barriers are a prime example of this
type of product.
Insul Holz-Beton International, a South
Carolina-based firm, produces a variety of
building products from cement-wood composites, includingFaswallO wallforms, framing blocks and asound barrier. According to
Hans Walter, presidentof the company, the
process uses a1 O : l ratio ofwood waste to cement.
Wood residue is finding ahome as a filler
in numerous plastic products. One market is
the plastic lumber sector, where at least a
few manufacturers are utilizing up to 50 percent wood fiber to strengthen and improve
the workability of the finished product.
A more exciting development isthe useof
wood residue in more traditional plastic
products. Several years ago, FPL identified
the potential of using wood fiber as a reinforcing filler in plastics. Advantages include improving a product’s strength and
dimensional stability, lower materials
in
costs, reduced product weight and less processing time (because the wood allows the
product t o cool faster in themold). However, this work was met with a less than enthusiastic response from the industry. It
w a s a classic Catch-22: plastic compounders (firms that blend various fillers,
additives and plastics)
weren’t interested in
producing an untried compound. Similarly,
plastic product manufacturers, not fully
aware of the advantages and without an adequate supply of wood-filled plastic, weren’t
interested in usingit.
To overcome this situation, the FPL embarked on a demonstration project in 1994
to develop compounding methods for introducing wood fiber into plastics, inform plastics manufacturers about the product, and
Timber shortages
in the Northwest
led Willamette
Industries to utilize
urban wood to help
supply its
particleboard mill
Eugene, Oregon.
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BIOCYCLE
DECEMBER
1996
37
I
Photo courtesv of Strandex Coro.
a modest dip in the sawdust bin.It is more
likely that wood-plastic products aimed at
replacing solid wood, as particleboard does,
have greater potential t o remove sizable
piles of wood residuals. One such product
highlighted at the Adding Value Workshop
is StrandexB, a wood composite profile
made from a blend of 70 percent wood or other cellulose and 30 percent plastic resin.Because of its water resistant properties, it is
used to replace wood in products such as
windows, doors and skylights.
BURNING WOOD, A NEW WAY
Extruded wood-plastic
composites with water
resistant properties canbe
used for products such as
exterior deckingJ
siding
window sills.
and
Making life easier for homeowners has
spawned a new use for wood residuals. While
many people like the idea
of burning wood at
home, the work involved is definitely a hindrance. Over the pastfew years, fuel pellets
demonstrate the useof wood-derived fillers made from wood residue have begun to be
in commercial applications, says Englishof marketed for use inspecially designed pellet
stoves. The pellets offer convenience and
FPL. The product demonstrations ranged
from flower pots toautomobile parts. In all, burning efficiency when compared to cordwood (leaving less than one percent ash).
18 manufacturersconductedtestsonthe
The pellet market hasgrown substantialwood-plastic blends. As described in theaccompanying article ("Recycled Wood and ly over the last several years. During the
Plastic Composites find Markets"), several 1993-94 heating season, pelletsales were escompounders are producing wood derived timated to be 523,000 tons. By 1995-96,
sales from the more than 60 pellet mills in
fillers in various formulations.
While wood derived fillers may find a North America had grown to 654,000 tons.
niche in theplastics industry, fillersaccount According to the Pellet Fuels Institute, the
for less a than four million pound per year retail price for wood pellets ranges from
midwest to$120 per
market. Evenif wood residue captureda siz- about $90 per ton in the
in
ton
that the
still
is only
able portion of that market, northeast.
..
.