Is Biomass Harvesting Sustainable?

Biomass Magazine
August 25, 2008
By Jerry Kram

Biomass can save the world or so we are told. The twin specters of looming energy shortages emptying our wallets and global warming melting glaciers make finding a solution for our petroleum addiction urgent from both a financial and environmental perspective. However, there is a cost to producing and converting biomass into fuels and electricity.

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.”

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.”

Loggers Adapt Another aspect of the study was trying to capture the logger’s voice, as the study titled one of its chapters. There is a large body of academic literature on removing biomass for energy or forest management, but very little of it comes from the perspective of the operators who actually do the work of cutting the trees and moving them out of the forest. “We found that in many instances existing equipment could be adapted to biomass harvesting,” Arnosti says. “But operating training and experience greatly increased productivity. For example, a particular logger that worked on a number of our tests figured out on his own how to carry two or three times as much biomass in a forwarder as he did at the beginning of the project. He figured it out and it was very different than the techniques he used to forward round wood.” A forwarder is a piece of equipment used to move wood from the cutting area to the collection area.

Abbas did most of the formal interviews with the loggers. She says one of the most profound differences for the loggers is that they had to walk every area before they would bid on clearing and collecting the biomass. Usually experienced loggers, who have worked a particular region, are familiar enough with the costs and paybacks of gathering round wood that they can calculate the expected costs and paybacks just from looking at a map of a timber offering. Gathering biomass was so different for them that they needed to walk the land to understand the pitfalls they would be facing. “It was normal for them to go into an area and extract a larger tree from the site,” she says. “But this was the first time they would enter a site solely to remove the smaller material.”

Arnosti described logging work as something so familiar to the workers they could do it on “semi-autopilot” which allowed them to become very skilled at what they did. Abbas found that one of the skills that made loggers so efficient was that they knew how to fell trees and position them so that the workers moving the trees out of the woods could do so with the least amount of wasted time and effort. For biomass harvesting, the loggers had to relearn these skills. “It was important that operators communicated with each other on the site,” Abbas says. “For example, they learned which machine would follow the next. So the operator would cut the material to be forwarded in a way, even though it would have taken him longer, that made the entire operation more efficient. But if you get a divided operation, where someone is responsible for cutting the material without thinking of the best way to lay it out, then you get a lot of hours of harvesting and that isn’t a very practical option for the loggers.”

At current prices, Arnosti says biomass cannot pay its way out of the woods. Biomass is likely to remain an adjunct to fuel reduction, habitat management or disease control operations and timber harvests. “What I have concluded is that biomass, at least woody biomass will likely forever be a coproduct,” he says. “It cannot be seen as the single reason you are doing land management. In the case of timber, the value of the wood will cover the cost of harvesting it, moving it and delivering it to a market at a profit. Even with today’s high energy prices, and based on our analysis, even if energy prices doubled again, we would find the costs of cutting, processing, transporting and delivering biomass would exceed the market value of that biomass.”

If the Forest Service wants to make biomass harvesting an integral part of its forest management practices, it will have to be more flexible in its regulations. As Arnosti points out, these regulations were developed for high-value round wood timber operations. There were times during the study when operations had to be shut down because the wrong species or wrong size tree was felled. “You can’t just follow the existing guidelines and assume it is going to include biomass harvesting,” Abbas says. “They need to be more practical and open with the loggers.”

Along with the ecological and logistical concerns about the harvesting system, economic questions also had to be answered. If biomass harvesting doesn’t pay for any of the players in the economic chain, then the entire system breaks down. “If you are talking about sustainability, then economics is one of the pieces you have to look at,” Current says. “Right now, with the payments from the Forest Service you can do this economically—in other cases, maybe not.”

Because the material that was collected for the study was usually just burned or bulldozed, there wasn’t much good economic data on what it costs to collect and deliver it to processors. “I think we are still learning how we can make these systems work,” Current says. “One thing we took out of this is that there are many studies that estimate the amount of biomass we can take out of state, private and federal sources, but there is still the question of the economic availability of that amount of biomass. That’s a question we need to look at more closely.”

While some biomass energy business plans assume that there are plentiful supplies of free or low-cost biomass, the owners of that biomass will expect to be paid for it. In some cases, biomass will be cheap because the alternative is paying the high cost to dispose of it in landfills or incinerators. However, that scenario will not be universal. “There are some loggers who are doing this collection now, but there is going to be a price threshold for that,” Current says.

NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is distributed without profit to those who have expressed a prior interest in receiving this information for research and educational purposes.

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