BRDI Waste to Wisdom: Results from Preliminary Biomass Briquetting

The Biomass Research and Development Initiative (BRDI) Waste to Wisdom project is studying various pathways to increase the value of forest residuals and decrease transportation costs to bring this underutilized resource into the renewable energy market. Densifying waste biomass into briquettes during forest operations may achieve both of these goals by converting it into a valuable heating fuel that is easily transported due to its high density and low moisture content.

SERC Project Manager Dave Carter operates the briquetter.

SERC Project Manager Dave Carter operates the briquetter.

Last April, SERC engineers, alongside partners from Pellet Fuels Institute and RUF Briquetting Systems, operated a commercial briquetter with a variety of feedstocks at Bear Mountain Forest Products’ manufacturing plant in Cascade Locks, Oregon. Electricity consumption and biomass throughput data were collected in the field, while a pallet containing feedstock and briquette samples was shipped to SERC for material analysis. Back at SERC’s lab, the samples were sent through a suite of tests to assess the quality of each briquette and determine which feedstock properties influence the end product’s characteristics, such as density, durability, grindability, and moisture absorption.

Briquettes produced from chipped biomass exit the briquetting machine.

Briquettes produced from chipped biomass exit the briquetting machine.

Results show that this briquetting system increases the volumetric energy density of chipped biomass by nearly 250%, producing briquettes with an average packing density of 720 kg/m3. Feedstocks with moisture content exceeding 15% produce lower density briquettes, which expand in height after exiting the briquette press. High moisture content, however, does not significantly impact briquette durability. Instead, the feedstock’s particle size distribution has the greatest effect on briquette durability. Feedstocks comprising mainly large particles, especially chipped biomass, do not bind together as well as fine or ground particles. To improve durability, chipped biomass can be combined with sawdust, which increases briquette durability two-fold and results in briquettes with a binding strength similar to those produced from pure sawdust.

These results help frame and guide our future work with biomass densification. In the next stages of this project, the multidisciplinary BRDI research team will investigate whether the upstream energy investments in drying and particle size reduction are worth the payback when bringing briquettes to the heating market.

BRDI Waste to Wisdom: Summer 2015 Testing

Late last spring, the BRDI team began acquiring testing apparatus and field equipment needed for torrefaction, drying, and briquetting of biomass at a test site located on Green Diamond property at Big Lagoon. The area, a demolished mill site, consisted of dilapidated cement, old iron railings, and overgrown shrubs. Drawings had already been prepared for electrical lines, equipment placement, and emergency evacuation locations for the test site, so site set up proceeded quickly.

From right to left: the torrefier trailer, the biomass drying unit, and the homemade chip screener used to sift feedstocks to acceptable chip sizes.

From right to left: the torrefier trailer, the biomass drying unit, and the homemade chip screener used to sift feedstocks to acceptable chip sizes.

The torrifier was a pilot unit custom-built by Norris Thermal Technologies (NTT) and hauled on a trailer over 2000 miles from Indiana. This was the largest piece of equipment on site and was the main focus for our summer testing of feedstocks at various temperatures and dwell times. NTT also provided a drying unit, which was purchased by BRDI for future biochar field-testing. This is the same type of drying unit used in many industries, including food and agriculture. BRDI’s application of the dryer was unique in that it used waste heat from the torrifier to dry the feedstocks to varying degrees of moisture content. The team found that moisture content in the woodchips, hard to control due to the combination of summer rains, early fog, and blazing mid day heat, had a significant impact on torrefaction. Moisture content in samples also affected the briquetting of the woodchips. Dry feedstocks of small particle sizes were observed to form dense briquettes of uniform size. Briquettes made of larger wet chips tended to crumble easily, and if the moisture content was high, the bricks expanded and deformed. In addition, because water is incompressible, too much moisture could damage the process mold and hydraulic pistons used to densify the woodchips into briquettes.

The summer testing team from left to right: Yaad Rana, Andy Eggink, David Carter, Greg Pfotenhauer, Kyle Palmer, Anna Partridge, and Marc Marshall.

The summer testing team from left to right: Yaad Rana, Andy Eggink, David Carter, Greg Pfotenhauer, Kyle Palmer, Anna Partridge, and Marc Marshall.

Overall, testing was successful and the BRDI team has a plethora of samples to analyze in the lab. An exciting year is expected, as analysis is performed in preparation for continued testing using full-scale equipment next summer.

BRDI Waste to Wisdom: Torrefaction Partner Selected

As reported previously, SERC is leading the biomass conversion technology demonstration portion of the Waste to Wisdom project. Waste to Wisdom is examining the entire biomass supply chain, from collection, transportation, and pre-treatment of the material in the woods, to the conversion of the material into energy and other marketable products. Our role is to oversee the testing and evaluation of three biomass conversion technologies: a biochar unit, a briquetter, and a torrefier.

We are pleased to announce that the Norris Thermal Technologies (NTT) of Tippecanoe, Indiana is joining the project as the torrefaction research and development partner. SERC conducted a competitive selection process involving 10 firms currently operating in the biomass torrefaction space. NTT’s proposal stood out due to the readiness of their team’s technology and their ability to field mobile torrefaction systems at two different scales within the project’s budget and schedule constraints.

NTT's pilot torrefaction unit.NTT will provide a pilot-scale torrefaction unit (see photo at right) for field-testing during the summer of 2015. This unit, which was recently operated alongside two other biomass conversion units in a demonstration sponsored by the Washington Department of Natural Resources, is trailer mounted and will be modified and then delivered to a forest operations site of our choosing near Arcata, CA.

After completion of pilot testing, NTT’s team will build a larger torrefaction reactor of the same design and retrofit it into a shipping container. NTT will then ship this containerized unit to Arcata for testing at a forest operations site and provide an operator for testing. Testing of the larger unit is currently scheduled for the summer of 2016. We are looking forward to continuing our biomass conversion research efforts with such a strong industry partner and we are confident that the torrefaction research objectives of the Waste to Wisdom project will be met through collaboration with NTT.

BRDI Waste to Wisdom

biochar machine2

Biochar unit with instrumentation installed for testing.

In late July, Marc Marshall, Mark Severy, and I traveled to Pueblo, Colorado to conduct testing on a biochar production machine manufactured by Biochar Solutions Incorporated (BSI). The purpose of our three-week trip was to collect experimental data for use in evaluating stand-alone operation (i.e. without an external source of energy to power the process) of the biochar unit as part of the BRDI project.

Infrared image of biochar unit flare during operation.

Infrared image of biochar unit flare during operation.

Biomass conversion technologies (BCTs), such as the BSI biochar machine, can create higher market-value products in near-woods environments, justifying the transport of these products to market. This in turn could allow fuels reduction and forestry residual management projects to be implemented in greater numbers thereby reducing greenhouse gas emissions and the risk of catastrophic wildfires. One of the goals of the BRDI project is to explore whether stand-alone operation of BCTs improves the economic and environmental benefits of removing slash and other woody residues from the forest.

We spent the first week in Pueblo installing instrumentation on the machine and setting up the data acquisition system. During the second and third weeks, we conducted experiments producing biochar with various biomass feedstocks.The variations in feedstock included tree species, particle size, anatomical distribution, percent contamination, and moisture content. Additional experiments led to design changes in the feedstock drying system and the air injection system for the flare.

The machine generates significant heat while operating (see photo at right). Some of this thermal energy is used for drying feedstock and some is used to preheat fresh air that is injected into the flare for complete combustion. Beyond the heat used for those purposes, there is a significant amount of high quality thermal energy that could potentially be used to generate electricity to power the machine at a forest landing site. Over the coming months, we will analyze the data and evaluate technologies that could be paired with the biochar machine to generate process electricity for stand-alone operations in near-woods environments.

Forest Biomass Energy: Looking for the Big Picture

This spring SERC embarked on a major forest biomass energy research project in partnership with Humboldt State University’s forestry department and researchers, entrepreneurs, and natural resource management agencies from a number of western and midwestern states. The “Waste to Wisdom” project will examine the entire supply chain of biomass, including collection, transportation, and pre-treatment of the material in the woods, as well as conversion of the material into energy and other marketable products using a variety of emerging technologies. Experts in economics, life cycle analysis, and environmental impacts will assess and compare the different biomass pathways.

BRDI-group

Mike Alcorn, chief forester for Green Diamond Resource Company, shows the BRDI research team a site where material is collected for use at Humboldt County’s biomass power plants.

The project officially launched with a kick-off meeting at HSU on May 13 and 14. The project’s thirteen principal investigators as well as several other stakeholders gathered to meet one another and discuss how to coordinate the many components of this complex effort. The meeting included a trip to a nearby timber harvest site on Green Diamond Resource Company land where state-of-the-art technology and logistics are being used to gather, chip, and haul slash for use in Humboldt County’s biomass power plants.

BRDI PIs

SERC director Arne Jacobson, U.S. Forest Service economist Ted Bilek, and HSU forestry professor Han-Sup Han will lead BRDI’s three research teams.

SERC’s role in the project is to oversee the testing and evaluation of three different types of biomass conversion technologies (BCTs): a biochar unit, a torrefier, and a briquetter. Biochar is solid, carbon-rich biomass that has been treated at high temperature, above 500°C, and is used principally as a soil amendment. Torrefaction takes place at a lower temperature, near 300°C, producing a solid fuel that can be directly substituted for coal in existing power plants. Briquettes are made near ambient temperature by compressing finely ground biomass and can be used in place of cordwood in biomass-fired heating and power generation systems. An important goal of Waste to Wisdom is to adapt each of these BCTs for mobile, stand-alone use at remote sites where utility service is not available. Decentralized deployment of these BCTs could be an economically viable alternative to the costly collection and transportation of raw biomass from far-flung timber harvest and wildland fuel reduction sites.

The $7.45 million, three-year project is sponsored by the U.S. Department of Energy through the Biomass Research and Development Initiative (BRDI) program, jointly supported by the U.S. Department of Agriculture. Each of the collaborating partners is making a cost share contribution to the project’s total budget. SERC’s share of the federal funding is $900,000, to which the lab is adding $185,000 worth of labor, equipment, and facility use.

SERC director Arne Jacobson will act as principal investigator for the BCT evaluation component of Waste to Wisdom. “We are excited to be involved in this project. We have a great set of partners, and we look forward to a successful effort.”