Bundling Up BTUs

Northwest forest industry first to witness entry of energy wood harvester into North American market

By Tony Kryzanowski

In the wake of homes and thousands of acres of merchantable timber lost to wildfires, the forest industry now has a new tool to remove slash from the forest and help prevent forest fires. It is called an energy wood harvester, a piece of equipment that essentially is a mobile slash compactor and bundler. The technology was developed and patented by the Timberjack division of John Deere, and it has been used in European forests for the past four years. Over 20 units are currently working in Scandinavia, as well as Spain, Italy and the UK.

Investing in Biomass Energy
Eventually, use of the energy wood harvester could provide North American loggers with another income stream. Slash normally piled and burned is already finding a market, as feedstock for biomass power-generating plants in some places, and in the manufacture of biofuels. The biomass logs manufactured by the energy wood harvester also have potential in erosion control and fish habitat rehabilitation programs. Whether the energy wood harvester can be run profitably, however, remains to be seen. “If a contractor is going to buy this machine, he has to make money running it,” says Bob Rummer, Project Leader with the USDA Forest Service Southern Research Station in Auburn, Alabama.

Purchasing an energy wood harvester requires an investment of about $450,000. Rummer says that in the short term, this tool could make money in niche applications—for example, within a 60-mile radius of an existing biomass power-generating plant where there are significant volumes of slash available. Or it could be put to use in areas where a portion of existing hazardous fuels treatment funds are directed toward supporting the utilization of energy wood. Longer term, as legislation comes into force restricting or banning slash burning, people living in forested areas around the country begin to realize the potential of slash as a renewable and plentiful energy resource, and more biomass power-generating plants are built, the use of the energy wood harvester could become a key component to economically bundle and transport slash to these biomass energy plants.

Trial Run
Northwest loggers were the first to witness the energy wood harvester in action through a series of demonstrations sponsored by the USDA Forest Service and John Deere/Tim-berjack. Rummer says this was an unusual situation where a study to collect data on the energy wood harvester’s performance, as well as an introduction of new technology to North America, happened at the same time. “We wanted to let people kick the tires on the unit,” he says. “Speaking for myself, I can see many applications for this machine.”

He adds that the Northwest was identified as the most likely area where this new technology would take hold, because the region fits a certain profile where use of an energy wood harvester could make both practical and economic sense. For example, considerable volumes of biomass are expected to be generated in the area because of the buildup of small-diameter wood fiber and logging residues from aggressive fire suppression programs. Both Rummer, and Dave Wellman, of Bearhaven Consulting, formerly Timberjack Advanced Harvesting Team Leader for Western North America, say that interest from people at these demonstrations was phenomenal, and embodied a wide spectrum. “There were a lot of people out there that I didn’t expect to see,” says Well-man. In addition to forest industry people and government representatives, the demos also attracted representatives from the National Association of Fire Chiefs and concerned local citizens.

Built to Bundle
Timberjack’s energy wood harvester is designed around the company’s basic 1410D short frame forwarder, with a special rear frame design. Additional software has been added to the forwarder’s standard Total Machine Control (TMC) system to operate the functions needed to compress and bundle slash. “We’re taking what is normally considered a waste product and somewhat of a fire hazard, compressing it, and making a giant fire log or fuel log that can be burned in co-generation plants that produce electricity,” says Wellman. The energy wood harvester solves the transportation problem of packaging fuel at the harvesting site in such a way that the bundles can be easily stored until needed and economically transported directly to biomass power plants, and chipped or crushed when needed. The equipment operator uses a grapple to retrieve slash and place it at the receiving end of the energy wood harvester ’s compression system.

The slash goes through a series of compression processes. The first consists of four rollers, then a fixed compacting unit, and then a third compactor that moves with the bundling ring containing the rolls of twine. Once enough material is compacted to achieve a set diameter, the bundling ring spins twine around the compacted log to hold the compacted material in place. When the bundle reaches its programmed length at the discharge end, it is automatically cut off and the process starts all over again. The computer program can be adjusted to change the length of the bundle, the number of twine wraps and the distance between wraps. “It’s possible to manufacture a log every 1.5 minutes if you have enough material and a skilled operator,” says Wellman. “The machine is fast enough to do that.” In Finland they average between 20 and 30 bundles per hour, depending on the skill of the operator and amount of material available. In many areas where energy wood harvesters are in use, a forwarder gathers the fuel logs and loads them onto standard shortwood log trucks for transport. Each fuel log weighs about 1000 lbs., depending on the dryness of the material.

Saving Energy and Environmentally Sound
From an energy standpoint, burning chips derived from 16 of these bundles will provide the electrical needs for the average family for a year. Looking at it another way, two fuel logs deliver the equivalent energy of a barrel of oil. The energy wood harvester also delivers a number of environmental dividends. The first is reduced soil compaction in the cutblock. “In a lot of areas, the slash is piled with an excavator or log loader, then burned,” says Wellman. “That means more travel on the site and more ground compaction. This machine has very low ground pressure.” Also, that power is being generated from a new, renewable resource, which will add to the overall power grid and reduce the possibility of brownouts and blackouts.

Only two-thirds of the slash is removed from the site. One-third of the cones and branches are left in the cutblock to leave some genetic material behind, to encourage a certain amount of natural regeneration, supply nutrients to the soil, and provide wildlife habitat. Finally, the process of gathering, compacting and bundling the slash into fuel logs is considered carbon dioxide neutral from a global warming standpoint. In other words, no more carbon is released into the atmosphere in the gathering, bundling and burning process than a tree absorbs during its life cycle. Prevention of wildfires, which release a considerable amount of heat and carbon into the atmosphere, is also another positive step in the effort to reduce global warming.

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