BioCycle January 2010, Vol. 51, No. 1, p. 38
Downturn in construction has caused a shortage of woody waste streams, while demand for biomass to produce energy has risen. The net effect has been challenging to wood recyclers in some regions.
Nora Goldstein

FOR several years, mulch producers and composting facilities have seen more competition for feedstocks from biomass power plants and wood pellet manufacturers. In some regions, locally generated wood waste was being processed for export markets as well. And then the construction market plummeted. Demand for lumber tanked, and with it went the availability of by-products such as sawdust and bark. Land clearing stopped in many regions, taking away that source of waste wood for recycling and composting as well. An added pressure in some states is the landfill industry’s continued attempts to repeal bans on disposal of yard trimmings, including wood.
“In addition, there continue to be plans announced for massive biomass power plants,” says John Foote, Vice-President of Sales at Morbark, Inc. “In Georgia and northern Florida alone, they are talking about 650 MW of new biomass power. That is about 8 million green tons of wood fiber per year. Huge pellet mills are being constructed as well. European demand for pellets is much greater than their supply, so we expect to see the export market getting stronger. Our prediction is that when the housing market comes back, even though the supply of wood waste generated by construction-related industries will be greater, the current market value will remain stable, i.e., demand will continue to grow from energy markets. These biomass plants, are great for local economies, including employment and clean energy solutions. However, compost and mulch producers will need to have a game plan in order to secure materials they need to meet processing and product demands.”
On a national level, there isn’t a shortage of woody material. The challenge is how to access it economically. For example, forests in the West, from New Mexico and Colorado to British Columbia, are filled with diseased trees. “Transportation and markets are what become the key factors,” notes Tim Adams, Marketing Manager at Morbark. “When you are transporting wood for energy, you need to maximize the Btus. Chipping whole trees at the source, making the loads as dense as possible, is a good solution. Morbark saw this coming and increased its capacity to manufacture more whole tree chippers.”
Biomass power plants’ need for wood hasn’t been a total negative to composters and mulch producers. “The increase in demand for biomass has helped some composters sell their screened woody overs to the energy market,” says Todd Dunderdale of Komptech USA, Inc.

EQUIPMENT INNOVATIONS TO MEET NEW DEMAND
The shifts in markets for waste wood also have led to shifts in wood processing equipment sales. “The energy market is starting to prefer a chipped product versus a ground product,” says Foote. “Wood chips flow through the system better than shredded mulch. We started seeing a shift in our market away from grinders and toward our chippers.”
Jerry Morey, President of Bandit Industries, also sees a tremendous demand for chipped wood for biomass energy plants. “The majority of these facilities will come on line in 2011 and 2012,” he says. “They will use a conventional size chip versus a finer ground material like sawdust that is used by pellet manufacturers. And I believe the lion’s share of those conventional chips will be made by whole tree chippers processing forest products and urban wood waste.”
To service the pellet manufacturing industry, Bandit introduced a new technology for its Beast Recycler to produce one-quarter-inch minus sawdust-type material (“biosawdust”) from debarked round wood in a single pass. “We have been selling equipment to process materials such as rice straw and sugar cane for use in ethanol production as well as for combustion,” explains Morey. “To use the rice straw, the fibers have to be really short. So we put a special tool into the Beast to process material to a fine consistency and be able to push it through the screen. We then saw application for the tool to produce a fine sawdust for pellet manufacturing.”
He adds that when Bandit was founded in 1983, its market focus was on tree care and land clearing applications. Only recently has the company begun focusing on forest products and energy applications. “This has become a main market for us in the last five years,” says Morey. “Things have changed dramatically with these energy plants coming on line and demand for chippers to process feedstocks for these facilities.”
To service its grinder customers who want to produce chips to sell to energy markets, Morbark introduced the Quick Switch conversion kit. It can be installed on several of the company’s horizontal grinders. For example, the Quick Switch for the 3800 and 4600XL Wood Hogs consists of knives in a staggered pattern. “The unit costs between $25,000 and $45,000, depending on the grinder,” says Foote. “Depending on the settings, wood recyclers can produce over 60 tons/hour of one-quarter-inch material. They are now able to supply local energy and mulch markets within the same day if needed with the same machine.”
Komptech introduced its Crambo Forest model specifically to enable its customers to tap available wood in forests. “This version of our Crambo wood shredder allows the supplier to bring one machine into the forest and produce cogeneration fuel in one pass,” explains Dunderdale. “All the unwanted dirt, rock and needles are left on the forest floor. At the moment, we have seen that funding for many projects to clear diseased wood out of forests has been delayed. And this time of year, harsh winter conditions make processing nearly impossible.”
The diminished supply of land clearing and cleaner construction-related wood streams also has led more wood recyclers to tap mixed construction and demolition (C&D) debris streams. Bandit is introducing a metal extraction device in mid-2010 to remove contaminants prior to processing in the Beast models. The unit will also have application in the shingle recycling industry. Morbark has been testing a slow speed shredder design at a mixed C&D debris processing facility, which has the capability to handle more contaminated feedstocks.

C&D WOOD IN CONTAINER MEDIA
RECENTLY completed research at Washington State University (WSU) in Puyallup showed promising results for wood recycled from construction debris in a container potting media. The study report, “Creating High Value Potting Media from Composts Made with Biosolids and Carbon-Rich Organic Wastes,” by Rita Hummel, Craig Cogger, Andy Bary and Bob Riley of WSU, describes the research findings, which evaluated several carbon-rich feedstocks available in Washington State. According to the report, “the market value of potting media in the Pacific Northwest (Washington, Oregon, Idaho and British Columbia) was recently estimated at $130 million. The main ingredients are nonrenewable resources including sphagnum peat, perlite, and/or vermiculite. Use of locally available renewable resources could provide more sustainably produced potting media while boosting the local economy.”
Biosolids composts have the potential to be a major ingredient in locally produced potting mixes, add the authors. “A large number of carbon-rich materials are available in Washington State, and these could be composted with Class B biosolids to make a Class A product suitable for use in potting mixes. Woody construction debris, land clearing debris and horse manure are abundant in urban areas of western Washington, such as King County … Container growing media must be porous and well drained but at the same time have sufficient water and nutrient retention to sustain and nourish plants.”
Composts were made from King County biosolids (1 part by volume) blended with construction wood (ground and screened construction debris from Recovery 1 in Tacoma, Washington), land clearing debris or horse manure (3 parts by volume). Finished composts were screened (7/16 in.) and blended 1:1 (v:v) with aged Douglas-fir bark to produce potting mixes. They were compared with an industry standard peat-perlite mix. Overall, notes the report, “Experimental biosolids composts with horse manure, construction debris and land clearing debris mixed with Douglas-fir bark performed equal to the peat-perlite control for growing marigold and sweet pepper.”
The construction debris-biosolids compost had the largest coarse fraction and fewer fines compared to the peat-perlite standard, even after mixing with bark. The coarseness of the experimental potting mixes was reflected in their high aeration porosity and low water holding capacity. “Water holding capacity of the experimental media was still within the acceptable range of 20 to 60 percent, but less than the ideal range of 35 to 50 percent,” note the authors. “Aeration porosity was slightly higher than the ideal range of 10 to 20 percent.”
“…The drip irrigation regime may have compensated for the reduced water holding capacity of the experimental mixes. Although plants performed well under the conditions of this study, they may not perform as well under different irrigation systems or management. This suggests that additional work could be done to improve the quality and consistency of the products, perhaps by custom grinding or screening of the woody feedstocks.”