First of its kind test focusing on screening woody biomass to produce quality feedstocks

First of its kind test focusing on screening woody biomass to produce quality feedstocksCraig Rawlings and I recently spent two cool, overcast days in Eugene, Oregon observing a test to develop new screening technologies for use in-woods with grinders and chippers. The test, conducted by the Waste to Wisdom project — Task 2 Team — experimented with two screening systems (star and deck) using chipped materials from pulpwood and hog fuel ground from logging slash.

Scroll below to get a closer look at this study, which is part of the efforts to produce quality feedstocks for biomass conversion technologies in the Waste to Wisdom (W2W) project. An in-depth photo essay will be available in the upcoming Waste to Wisdom website, which is expected to launch next month.

About W2W

W2W is a $5.88 million U.S. Department of Energy-funded effort that seeks to find a cost-effective and efficient means to process, transport, and convert leftover forest residues from logging operations and forest thinnings so it can be used in bioenergy and bioproducts. The project lead — Humboldt State University — is accompanied by 15 regional partners, including Forest Business Network, over the 3-year effort.

Waste to Wisdom Feedstock Screening Test

Subtask 2.4: Controlling feedstock size with new screening technologies

This task will develop new screening technologies for use as part of in-woods biomass conversion operations. It will focus on the effects of incorporating these innovations into biomass operations with the intention of improving product quality and meeting particle size requirements for biomass conversion technologies.

Where: Lane Forest Products in Junction City, Oregon

When: January 12–13, 2015

Participating organizations/companies:

  • Forest Operations Research Laboratory, Humboldt State University
  • Peterson Pacific Corporation
  • Lane Forest Products
  • Forest Concepts Inc.
  • Oregon State University

Feedstock info:

  • Chipped materials from pulpwood of primarily small-diameter Douglas fir and some other conifer species
  • Hog fuel ground from logging slash consisting of limbs, branches, tree tops, and chunks
  • Sourced from forest harvesting sites near Eugene, Oregon

Equipment utilized during the two-day controlled experiment:

  • Cat 930G front-end loader with 75 cubic yard “Tink” bucket
  • Truck with hydraulic roll-on/off container lift system
  • Three 30 cubic yard roll off containers
  • Peterson Pacific Model DS6162 track mounted disc screen
  • Peterson Pacific Model S6-E Terra Select track mounted star screen
  • Peterson 5900EL disc chipper set up to produce 7/8” chips
  • Peterson 4710 grinder equipped with outer hammer bits and inner knife bits on the rotor and a combination of three screens of 3-4-4 inches

Primary study objectives are to measure

  1. screening productivity (ton/hour) with three sorts (<5/8″, 5/8″-2″, >2″) for wood chips and hog fuel,
  2. diesel fuel consumption rates (gal/hour and gal/ton) for each screening machine, and
  3. analyze size distributions in the screened 5/8″ – 2″ materials.

The test will focus on the effects of incorporating these innovations into biomass operations with the intention of producing quality feedstocks from forest residues.

What we aim to achieve: Learning about two screening technologies and how they handle wood chips and hog fuel.

Significance: First of its kind test focusing on screening technologies for forest residues from forest harvest, fuels reduction, thinning, and forest restoration activities.

What does this mean for forestland owners and the forest industry? Will address whether or not forest residues are a good source as a biofuel and bioproduct feedstock.

Next steps:

  • Chip and hog fuel screen samples will be analyzed at Humboldt State University’s Forest Operations Research Laboratory
  • HSU researchers will compile a report on the two-day controlled experiment, including screening productivity, machine fuel consumption rates, and analysis of the materials screened

Tom Waddell is Forest Business Network’s Vice President of Sales & Marketing.


  1. Paul Weisner says

    One question I have with this biofuel source is the quality of the fuel. With logging slash, one can have dirt, rocks, needles, and other debris that can cause clinkers and other problems in burners and boilers from these contaminants. From a tour of school biomass heating plants in Montana in 2009, the main complaint I heard from school personnel was that low quality fuels with contaminants caused the most problems in the operations of their heating plants.

    I would imagine that there are biomass burners made for handling these type of fuels with contaminants, or applications that can utilize this type of forest waste.

  2. Tom Waddell says

    Paul, I reached out to Han-Sup Han from Humboldt State University, the organization leading the W2W project, and here is what he had to say:

    I agree. So, our study being done by the W2W team is to produce quality feedstock (uniform in size, low moisture content, and minimum moisture content) from forest residues. To make it happen, we are separating tree tops and small-diameter whole trees from slash piles during timber and thinning operations. Tree tops and slash materials are also arranged on site, so that those materials are not mixed with dirt and have lower moisture contents. Tree tops and small-diameter trees will be chipped while slash materials consisting of mainly limbs/branches and chunks will be ground. Our screening study is to further separate biomass feedstock that meets size specification requirements for biomass conversion techs from chipped/ground materials.

  3. Joe Thomas says

    If the landowner is receiving only .50 per ton,
    It would seem to be a profitable operation to produce fuel pellets ? Of course I do not know the manufacturing cost, but for export contracts, the price of shipping ( on hold ships ) to foreign ports would be relatively a substantial cost per ton. Value of fuel pellets ?