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.

RePower Humboldt: Biomass-Fired Fuel Cell Power System

The 175 kW biomass-fired fuel cell power system being installed at the Blue Lake Rancheria is nearly complete. The Proton Power gasifier has been installed and gone through initial start-up procedures, including heating up the gasifier to temperature and running the flare. The gas compression system (rotary claw compressor, syngas ballast tank, and reciprocating compressor) has been tested and the control strategy has been confirmed. The Xebec pressure swing adsorption (PSA) hydrogen purifier is installed and ready for testing, and the Ballard PEM fuel cell is in place and has undergone pre-commissioning. Most of the peripheral systems (biomass feed, control, fire alarm and life safety, cooling, and ventilation) are complete or very near completion. Our next steps will be to obtain a fuel with a moisture content no greater than 40% (wet basis); begin making syngas; test and confirm syngas quality; and then fully commission the PSA and fuel cell system, as well as the fully integrated system. We submitted a draft final report to the CEC in March, but work on the system will continue over the next few months until we achieve full system operation and performance testing. Following these activities a revised final report will be submitted.

The Proton Power biomass gasifier installed at the Blue Lake Rancheria.

The Proton Power biomass gasifier installed at the Blue Lake Rancheria.

BRDI Waste to Wisdom: Remote Power Generation and Summer Testing

BRDI-2-webSERC continues work on the BRDI Waste to Wisdom project, a three-year, multidisciplinary project to study pathways to convert forest residuals – or slash piles – into valuable energy and agricultural products at processing sites near timber harvest locations. Many of the potential processing sites do not have access to electricity, so SERC has been analyzing various methods to power this industrial equipment in remote locations. With help from the Environmental Resources Engineering capstone design course, SERC completed a technical and economic feasibility analysis comparing various remote power generation technologies, including waste heat recovery, biomass gasification, solar photovoltaic, and others. The results from this paper study indicate that a biomass gasifier is likely to outperform the other technologies in terms of mobility, cost, reliability, and environmental impact. After presenting these finding to the U.S. Department of Energy, the funding agency for this project, we procured a mobile, 20 kW biomass gasifier (similar to the one in the photo above) from All Power Labs in Berkeley, CA. Once it arrives, we will begin a series of tests to evaluate whether its performance will meet the requirements to operate in the demanding conditions of a forest-landing site.

With the gasifier being fabricated and a torrefier and a briquetter being prepared for shipment, it’s shaping up to be an exciting and eventful spring and summer of biomass fieldwork. SERC will lead the effort to test the torrefier, briquetter, and gasifier generator set at a forest-landing site in Big Lagoon, CA. We will measure the performance characteristics of each machine with a variety of biomass feedstocks recovered from timber harvest operations here in northern California. In addition to testing these machines individually, their synergy in an integrated system will be evaluated by connecting them together. For example, we will conduct experiments to densify torrefied biomass and to evaluate whether the gasifier generator set can reliably provide electricity to the other machines. Having these three commercial-scale technologies at a single site provides a unique testing and demonstration experience.

To prepare for this fieldwork, we have been busy developing the testing matrices, procuring feedstocks, detailing our instrumentation plans, preparing our data analysis tools, and coordinating associated logistical issues. The entire BRDI team is looking forward to a productive season of data collection and analysis that will help address the key issues posing a barrier to recovery and utilization of forest residual waste.

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.

RePower Humboldt: BLR Biomass Facility Ventilation System Design Complete

Model of syngas concentration 5 minutes after a leak with the original (top) and final (bottom) ventilation designs. The pink areas are the zones where the concentration is immediately dangerous due to CO toxicity.

Models of syngas concentrations five minutes after a leak with the original (top) and final (bottom) ventilation designs. The pink areas are the zones where the concentration is immediately dangerous due to CO toxicity.

Last summer, the RePower team began evaluating the proposed ventilation system for the Blue Lake Rancheria (BLR) biomass energy facility. Each phase of the BLR gasification process involves a dangerous gas. First, biomass is processed into a syngas rich in hydrogen and carbon monoxide. This syngas is then processed into pure hydrogen and a waste gas rich in carbon monoxide. In normal operation, the syngas and hydrogen are fully contained, and the waste gas is safely burned in a flare. However, an accidental leak in the system could pose an immediate toxic or explosive danger. The ventilation system must give personnVentilation_Image_2el enough time to safely exit, and must clear hazardous gases from the building after the gasifier system shuts down.

To test different system designs, the RePower team used a software package from the National Institute of Standards and Technology to model contaminant flow in 3-D. We simulated various leak scenarios and examined how the placement of exhaust fans and intake vents affected the removal of toxic and flammable gases. We were able to improve on the original system design and create a more responsive, and robust system. The final design uses a combination of ceiling fans, wall fans, and floor vents to provide optimum ventilation. Following installation, the ventilation system will undergo a smoke test to validate the model results. Completion of this work will ensure a safe operating environment for the biomass facility.

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.”

RePower Humboldt: BLR Biomass to Energy Project

The design and procurement phases of the BLR Biomass to Energy Project are in full swing and the project team is involved in a flurry of activity. A group of engineers from SERC, as well as staff from Serraga Energy, LLC at the Blue Lake Rancheria (BLR) project site, are meeting weekly to discuss design decisions and move the effort forward. Frequent interactions are also taking place with our technology partners: Proton Power (gasifier), Xebec Adsorption (PSA gas cleanup unit), and Ballard Power Systems (fuel cell). Below is a list of key activities currently underway:

  • site layout is largely completed
  • fire marshal review – first phase is complete
  • site work has begun and will ramp up significantly over the next few weeks
  • gasifier is being fabricated – witness testing will occur in late July with delivery in August
  • PSA design and fabrication are underway – delivery is expected in late August
  • syngas compressor requirements have been specified and quotes have been obtained – orders will be placed in the next couple of weeks
  • fuel cell is on site – installation is slated for July or August
  • central control and monitoring system – design is underway
  • ventilation system – design analysis is underway
  • fuel storage and processing – design is underway
  • electrical service (auxiliary power supply and fuel cell generator/utility interconnection) – electrical engineer and contractor team are working on design, procurement, and the utility interconnect application with Pacific Gas & Electric
BLR site photo

Neil Harris (far right) with electrical and construction experts implementing site design at Blue Lake Rancheria. Photo credit Serraga Energy, LLC.

The next phases of the project will include component installation (summer and early fall 2014), system integration and commissioning (fall 2014), and system operation, data collection, analysis and reporting (late fall and winter 2014/15). Stay tuned for additional updates in upcoming newsletters.

Aqueous Phase Reformation

Researchers at SERC are studying alternative pathways for biomass energy to displace fossil fuels in existing high-efficiency power plants. Chemical reactions can harness waste heat to convert biomass into a hydrogen-rich syngas, displacing fossil fuel consumption. Modeling work at SERC estimates that integrated systems can produce between 5% and 100% of a power plant’s fuel requirement from biomass, depending on the quality of the waste heat resource. If applied to internal combustion engine power plants, blending hydrogen-rich syngas with natural gas additionally reduces untreated nitrogen oxide (NOx) emissions by up to 95% and increases engine efficiency by up to 25%.

Over the past year, SERC’s Dr. David Vernon led a research team to study aqueous phase reformation (APR) of plant-derived sugars to produce a hydrogen-rich syngas. This project, funded by the California Energy Commission, investigated the potential to use this low temperature reformation process to recover waste heat from natural gas power plants. SERC engineers designed, built, and tested a benchtop chemical reactor to convert aqueous sorbitol (C6H14O6) into an energy-rich gas consisting of hydrogen, carbon dioxide, and methane. Sorbitol, a sugar alcohol, was selected as the feedstock because it is easily produced from glucose, a biomass derivative, and reforming sorbitol produces hydrogen at a faster rate than reforming glucose.

Testing was completed in April. Our results showed that APR is able to convert up to 94% of the input sorbitol into a hydrogen-rich gaseous fuel. By synthesizing our own catalysts at SERC, we were able to produce a gas containing 64% hydrogen by volume. Furthermore, the output liquid and gas were found to contain 46% more chemical energy than the input feedstock.

Based on these promising results, we conclude that it is feasible to use APR in waste heat recovery applications. We have applied for additional funding to continue this work. Next, we plan to use crude glycerol, a byproduct of biodiesel production, as the feedstock. Our economic models predict that converting crude glycerol will significantly reduce the lifecycle costs of the system, making this process more cost competitive than other waste heat recovery technologies such as organic Rankine cycles.