Removing too much biomass can deplete nutrients from the soil and possibly increase erosion. Landowners, farmers, loggers and other people involved in the production and harvest of biomass need to be compensated and the price of biomass needs to cover those costs. Researchers from Minnesota and Wisconsin zeroed in on one particular system—small trees and undergrowth in the Superior National Forest—to gauge the environmental and economic costs of removing biomass from the forest.
The study was conducted by Don Arnosti of the Institute for Agriculture and Trade Policy, Dalia Abbas and Dean Current of the University of Minnesota and Michael Demchik of the University of Wisconsin, Stevens Point. “Is biomass harvesting sustainable?” Arnosti says. “That’s a very simple question about a very complex situation. I don’t think it has a simple answer. I guess the simplest answer I could give is that under the right conditions and with the right vision and moderation, the answer is yes. Would I validate people who would say it might be unsustainable in certain circumstances? That answer is also yes.”
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The IATP studies policies on food, trade and sustainability. In 2005, it received a grant to look at the barriers for sustainably harvesting biomass. The organization started looking at biomass resources because it noticed that the region’s pulp and paper industry had started to use more “dirty chips” for fuel. Dirty chips are the result of grinding or chipping whole trees, forest or green waste. They represent a readily available source of supply. However, the chips are of random shapes and sizes which could lead to feeding problems if using automated systems. This will also affect combustion. The contaminants (bark, foliage, dirt and others) will lead to higher ash content. Dirty chips are commonly referred to as “hog fuel” by forest contractors and forest industry personnel.
Some boiler systems (particularly at the larger scale) are designed to burn this type of chip. When using dirty chips it is important to match the boiler system with the supply.
“Back in 2005 biomass was not a hot topic, it became so with higher energy prices,” Arnosti says. “We really got involved in this study because we wanted answers. We wanted to
understand the economic barriers that were controlling the industry and the ecological boundaries of sustainability.”
Fire Prevention and Biomass Collection
The study looked at nine areas being cleared for fuel reduction to prevent forest fires. The material being removed was a mix of balsam fir that had been killed by spruce budworms and aspen in areas where understory balsam firs created ladder fuels that cause devastating crown fires in areas of taller 60- to 80-year-old red and white pines. The treatments varied by site but generally called for the removal of trees and brush smaller than a diameter of 5 or 6 inches at a point 4 feet above the ground. “We partnered with the [U.S.] Forest Service because they were already making fuel management a high priority, especially near urban areas,” Arnosti says. “It turns out that the Superior National Forest has a lot of development like that embedded in the forest. They were developing plans to reduce fuels and were eager to understand how biomass markets and harvest could factor into what, up until then, had been a cut, pile and burn fuel reduction.”
Arnosti says the researchers started out looking for the answer to two questions and quickly found they needed a third answered. They wanted to find out what equipment and techniques a logger would need to efficiently harvest biomass in the forest. The second question was what the ecological impacts of the harvest were. “The third piece that we kind of stumbled into was the administrative complexity—the land management mindset,” he says. “All of the procedures were set up with high-value timber in mind while biomass is a low-value product that probably will have to be harvested below cost. You can’t have loggers bidding to get [the Forest Service] the highest return on the contract when you are doing biomass and really subsidizing the removal.”
The main conclusion of the study was that there are many ways to interrupt a smooth supply of biomass to a market. “I’m not going to say there is only one way to get it right, but there are probably 14 different ways you can screw it up,” Arnosti says. The potential problems fall into the three broad categories captured by the researcher’s questions. “One, the administrators need to have procedures and practices in place that facilitate biomass harvesting,” he says. “Two, the contractors or loggers need to have training or experience in utilizing their equipment to harvest high-volume, low-value material. Finally, biomass markets have been developed with the assumption that the biomass material is going to be free or at a very low cost. That may be true if you are just picking up tops and branches at a timber harvest site, but if you want to get beyond the boom and bust volumes that come with the timber market, you need to recognize that pricing has to be greater than zero.”
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