Beetle-kill conundrum

Sara Lynn Grady
December 05, 2014
Written by Sara Lynn Grady
Dec. 8, 2014 - The mountain pine beetle infestation changed the landscape of forestry in British Columbia, visually, environmentally, and economically. Vast coniferous forests – the ones that aren’t a sea of red – have been reduced to what one forester called “stump farms,” and mills accustomed to a somewhat measured supply of timber have, at times, found themselves trying to drink from a fire hose.

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The current state of residual supply has the potential to spark a market – and regulatory – challenge that places pulp mills and pellet mills in direct competition for remaining resources.

One benefactor of the pine beetle invasion, which has devastated an estimated 18.1 million hectares of lodgepole pine forest in B.C.’s north and central interior, is the pellet industry. Response to this abundant source of raw material for pellet manufacturing has varied, and continues to evolve.

For some, the changes were made in harvesting practices; others have integrated new equipment into their mills; other mills were purpose-built based on the abundance of pine beetle material. Even as mills modify their production methods, the supply of beetle-kill waste may be dwindling, passing its useful lifecycle in manufacturing of any kind. However, the pellet industry is accustomed to riding the waves of construction boom-and-bust, regulatory changes, and environmental factors over which it has little, if any, control. As a relatively nascent member of the forestry sector, all it can do is adapt.

The initial wave of mountain pine beetle harvesting filled lumber yards across the province: annual allowable cuts were increased by the provincial government so that Crown licensees could salvage as much mill-worthy material as possible before it rotted in the forest; approximately 95 per cent of B.C.’s forests belong to the province, with five major companies holding control of the 75 per cent under long-term tenure agreement. The resulting sawmill residuals were a boon for pellet mills, and these residuals continue to fuel mills across the province.

The second wave of logging saw a shift in harvesting practices, and a change in raw material available to pellet mills. As pine stands died and degraded, licensees became more – or sometimes less – selective about what they cut down, and what they processed onsite. Pellet mills in the northern interior were no longer receiving chip trucks full of clean bush-grind; instead, they were taking horizontal grinders, like Pinnacle’s Peterson 4710B, to a landing site, grinding the material themselves and trucking it to their plants.

Whether destruction from the pine beetle has met or exceeded projections, the current state of residual supply has the potential to spark a market – and regulatory – challenge that places pulp mills and pellet mills in direct competition for remaining resources. As viable stands of green (still viable as lumber despite pine beetle infestation), red (mostly dead) and grey (completely dead and no use to a sawmill) pine beetle wood diminish within easy reach of logging contractors, the incentive for lumber mills to pay for logging and cartage of an already low-value harvest diminishes as well. Their priority is harvesting sawlogs, and in the remaining stands those are not in abundance. And slash piles, many full of viable pellet material, sit out of range, awaiting burning season rather than a long haul to a pellet mill.

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Pellet mills have had to work closely with logging contractors to get the cleanest possible material from their operations.

For plants like Pacific Bioenergy in Prince George, situated near pine beetle “Ground Zero,” the focus has been on getting clean material from slash piles. This has meant working more closely with logging contractors and their operators at landings; they are accustomed to pushing everything into a burn pile, scraping up rocks and dirt along with the residuals. It has also necessitated discretion when feeding the waste into a grinder: avoiding the material at the bottom of a residual pile, where most of the foreign debris has built up, reduces wear and tear on the grinder, and a cleaner product arrives at the mill. By investing in the labour to sort material before grinding, the company can realize nearly four times the lifespan for roll and die wear, saving maintenance and replacement costs.

Similarly, Pinnacle Pellet invests time working with logging contractors to get the cleanest possible material from landings. Once in their Meadowbank (Strathnaver) mill, however, material is passed through a purpose-built General Kinematics De-Stoner, designed in direct response to the abundance of pine beetle material. Using vibrating action and a series of air knives, fibre is separated and cleaned of dirt, metal, stones and any other foreign objects that may have contaminated the bush grind, based on velocity and density.

Some refinements had to be made for the De-Stoner to work effectively with the logging residuals: while pine beetle waste is traditionally bone dry, some would arrive with excess moisture due to the presence of green wood (such as spruce and balsam from higher elevation clearcuts) in the bush grind. The original finger screens tended to clog due to the excess moisture; screens would get wet as green wood passed through, and then get coated with dust from dry beetle wood, creating caked layers that choked the screens. After some experimentation, General Kinematics switched over to rod screens, which had been designed to manage reclamation of construction waste in wet climates like Florida.

Moisture variance has certainly been a factor for mills using pine beetle residuals, but achieving a consistent particle size remains the greatest challenge for efficient pellet production. Brunette Machinery has introduced the BioSizer, purpose-built to manage the wide variations in species and moisture content, and two of B.C.’s largest mills in the heart of pine beetle country have adopted this new equipment. The standard “hog” mill, operating at 650-750 rpm, has the capability to grind whole logs and sawmill residuals to 3-4” minus dimension. The Brunette BioSizer, used by Pacific Bioenergy and Pinnacle, produces a more consistent, smaller particle ideal for pelletizers – running at 1400 rpm, it generates 1/4” - 3/8” chips that dry more uniformly and efficiently, saving energy and time.

Industry estimates point to another 700 million cubic metres of mountain pine beetle still standing in B.C.’s forests. While northern pellet mills are poised to absorb the residuals from these dead-standing trees, the challenge remains: will the province’s key licensees have the economic will to recover the material so pellet mills can access them? During the initial clearing of pine beetle-kill logging contractors, understandably, harvested the “low hanging fruit” – the stands close to local sawmills and infrastructure. As that radius expands and the returns shrink, pellet mills may have to stand on the sidelines and wait for other motivation, either through market forces or government regulation, before the majors take down the trees.

Equipment manufacturers, like the pellet mills themselves, remain nimble in the face of changing fuel. Having successfully shifted from traditional sources of sawdust and hog fuel to slash piles with varying species, moisture and contaminant content, to processing, albeit infrequently, whole logs, there’s no doubt the biofuel industry will adapt to whatever future fuel becomes available to them.

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