Sisters forests produce biomass fuel

A project on the Sisters Ranger District is turning logging waste into electricity.

There was a time when the "guts and feathers" of a logging operation - limbs from harvested trees, brush, and other woody debris, known as "slash" - was left behind to rot or collected into burning piles. In some instances it was chipped and spread out on the forest floor.

In the late 1950s the Forest Service experimented with breaking up slash by running it through a flat bed chipper and spreading it out in the forest to add to the biomass. That didn't work out economically, and the energy required (nitrogen and nitrites) to break the wood fiber down into soil wasn't biologically efficient or good for the soil.

It became the responsibility of contractors (loggers) to gather all the slash and leave it in piles. This also caused further problems as topsoil was scraped away and compacted by bulldozers that introduced forest diseases. When hot weather turned cool and a prescription for burning was in effect, Forest Service fire people would set fire to the piles, and that was that, or so they thought.

This was less than desirable, however, as it left areas of scorched soil that was so sterile nothing would live in it for years. Nevertheless, piles that were not burned were quickly taken over by assorted wildlife for shelter. Pine Marten, a variety of rodents, and several bird species moved into them to keep out of harm's way and stay warm and safe in bad weather.

Despite those wildlife values, the vast amount of slash piles eventually became a blight on the landscape and a costly problem to deal with. Enter the Green Thin Stewardship Project on the Sisters District and Melcher Logging out of Sweet Home.

Green Thin is an opportunity to try out new ideas, one of which is grinding up slash and using it for hog fuel in biomass electric generating plants.

Melcher's outfit has the equipment that makes transporting forest slash easy, economical and friendly to the forest. A "forwarder," a small, diesel-powered machine mounted on wide rubber tires - and flexible as a snake - is equipped with a loading boom and large bin. The forwarder transports the debris to a central location. The slash is then piled into huge stacks of up to 800 tons each and ground into hog fuel.

Large chip trucks are used to transport the hog fuel to Roseburg where it is burned to create electricity that powers the mill. Surplus power is put into the grid. The price of electricity makes this a profitable operation, in spite of high fuel costs to transport the product from Sisters to Roseburg.

Concern over the removal of up to 3,000 tons of biomass from the Green Thin site is minimal. Because of unmanaged forests and the suppression of fire after logging in the '40s and '50s, crowding of young trees has created a surplus biomass.

According to foresters, removing the slash as hog fuel helps to keep forest health objectives on track and at the same time provides electricity for homes and income for the wood-products industry.