White Papers

On this page, we have been collecting links to relevant empirical and marketing white papers, which could be useful for our customers, partners, and employees.

Demand for biomass to meet renewable energy targets in the United States: implications for land use

Authors: Oliver, Anthony; Khanna, Madhu
Publication date: September 1, 2017
Source: Journal of Urban Cultural Studies, vol. 9, no. 9, pp. 1476-1488(13)
DOI: https://doi.org/10.1111/gcbb.12437
Keywords: Renewable Fuel Standard; Renewable Portfolio Standard; bioelectricity; biofuels; dynamic optimization; partial‐equilibrium model; spatial analysis
Document Type: Research Article
Abstract: Renewable energy policies in the electricity and transportation sectors in the United States are expected to create demand for biomass and food crops (corn) that could divert land from food crop production. We develop a dynamic, open‐economy, price‐endogenous multi‐market model of the US agricultural, electricity and transportation sectors to endogenously determine the quantity and mix of bioenergy likely to be required to meet the state Renewable Portfolio Standards (RPSs) and the federal Renewable Fuel Standard (RFS) if implemented independently or jointly (RFS & RPS) over the 2007–2030 period and their implications for the extent and spatial pattern of diversion of land from other uses for biomass feedstock production. We find that the demand for biomass ranges from 100 million metric tons (MMT) under the RPS alone to 310 MMT under the RFS & RPS; 70% of the biomass in the latter case can be met by crop and forest residues, while the rest can be met by devoting 3% of cropland to energy crop production with 80% of this being marginal land. Our findings show significant potential to meet current renewable energy goals by expanding high‐yielding energy crop production on marginal land and using residues without conflicting with food crop production.

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Recycle, Bury, or Burn Wood Waste Biomass?: LCA Answer Depends on Carbon Accounting, Emissions Controls, Displaced Fuels, and Impact Costs

Authors: Morris, Jeffrey
Publication date: August 1, 2017
Source: Journal of Industrial Ecology, vol. 21, no. 4, pp. 844-856(13)
DOI: https://doi.org/10.1111/gcbb.12437
Keywords: biogenic carbon accounting; biomass combustion; biomass combustion impacts; energy offsets; life cycle assessment (LCA); wood recycling
Document Type: Research Article
Abstract: This study extends existing life cycle assessment (LCA) literature by assessing seven environmental burdens and an overall monetized environmental score for eight recycle, bury, or burn options to manage clean wood wastes generated at construction and demolition activity sites. The study assesses direct environmental impacts along with substitution effects from displacing fossil fuels and managed forest wood sourcing activities. Follow‐on effects on forest carbon stocks, land use, and fuel markets are not assessed. Sensitivity analysis addresses landfill carbon storage and biodegradation rates, atmospheric emissions controls, displaced fuel types, and two alternative carbon accounting methods commonly used for waste management LCAs. Base‐case carbon accounting considers emissions and uptakes of all biogenic and fossil carbon compounds, including biogenic carbon dioxide. Base‐case results show that recycling options (recycling into reconstituted wood products or into wood pulp for papermaking) rank better than all burning or burying options for overall monetized score as well as for climate impacts, except that wood substitution for coal in industrial boilers is slightly better than recycling for the climate. Wood substitution for natural gas boiler fuel has the highest environmental impacts. Sensitivity analysis shows the overall monetized score rankings for recycling options to be robust except for the carbon accounting method, for which all options are highly sensitive. Under one of the alternative methods, wood substitution for coal boiler fuel and landfill options with high methane capture efficiency are the best for the overall score; recycling options are next to the worst. Under the other accounting alternative, wood substitution for coal and waste‐to‐energy are the best, followed by recycling options.

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Size, shape, and density changes of biomass particles during rapid devolatilization

Authors: Per Holmgren, David R.Wagner, Anna Strandberg, Roger Molinder, Henrik Wiinikka, Kentaro Umeki, Markus Broström
Publication date: October 15, 2017
Source: Fuel Volume 206, pp 342-351
DOI: https://doi.org/10.1016/j.fuel.2017.06.009
Keywords: PIV, DTR, Pyrolysis, Biomass conversion
Document Type: Research Article
Abstract: Particle properties such as size, shape and density play significant roles on particle flow and flame propagation in pulverized fuel combustion and gasification. A drop tube furnace allows for experiments at high heating rates similar to those found in large-scale appliances, and was used in this study to carry out experiments on pulverized biomass devolatilization, i.e. detailing the first stage of fuel conversion. The objective of this study was to develop a particle conversion model based on optical information on particle size and shape transformation. Pine stem wood and wheat straw were milled and sieved to three narrow size ranges, rapidly heated in a drop tube setup, and solid residues were characterized using optical methods. Different shape descriptors were evaluated and a shape descriptor based on particle perimeter was found to give significant information for accurate estimation of particle volume. The optical conversion model developed was proven useful and showed good agreement with conversion measured using a reference method based on chemical analysis of non-volatilized ash forming elements. The particle conversion model presented can be implemented as a non-intrusive method for in-situ monitoring of particle conversion, provided density data has been calibrated.

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Generalized categorical regression model for size reduction of multiple biomass and grinders

Authors: Manlu Yu, Igathinathane Cannayen
Publication date: 2016
Source: American Society of Agricultural and Biological Engineers, St. Joseph, Michigan
DOI: 10.13031/aim.20162461255
Keywords: Biomass, Energy, Modeling, Machine vision, Processing.
Document Type: Research Article
Abstract: Predicting the energy expended in size reduction process will affect the efficiency of the various conversion processes that biomass feedstocks undergo. Several factors as moisture content, particle size distribution (PSD – using machine vision) of the ground product, and the mechanical shear stress (using universal testing machine) of the stalks are expected to be significant to influence the specific size reduction energy (SRE). Grinding experiments using laboratory grinders and specific SRE measurements using clamp-on power meter were conducted on the selected big bluestem, corn stalks and switchgrass samples at moisture contents of 7%, 14%, and 20% d.b, using a knife mill and a hammer mill (both fitted with 3 different screen sizes). Parameters such as, moisture content, screen size, shear stress, geometric mean length, and uniformity index were selected for the SRE modeling. Best specific SRE models, based on stepwise linear regression of direct five parameters, gave very good (0.85 ≤ AdjR2 â‰¤ 0.97) while that with interactions (7 to 16 parameters) gave excellent (0.979 ≤ AdjR2 â‰¤ 0.999) model performance. Grinder specific generalized models had good performance for knife mill (R2 = 0.86) and hammer mill (R2 = 0.76) models, and a similar comparable performance was obtained for the overall generalized model (R2 = 0.83) that can make predictions irrespective of the crop and grinder used. Procedure outlined in the study for the newly developed generalized models can be applied to more devices and feedstocks. Models of SRE will help in better decisions on handling, processing, and utilization of biomass.

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Biomass pyrolysis—A review of modelling, process parameters and catalytic studies

Authors: Abhishek Sharma, Vishnu Pareek, Dongke Zhang
Publication date: October 2015
Source: Renewable and Sustainable Energy Reviews, Volume 50, pp 1081-1096
DOI:  https://doi.org/10.1016/j.rser.2015.04.193
Keywords: Biochar, Biomass, Hydrodynamic, Kinetics, Modelling, Pyrolysis.
Document Type: Research Article
Abstract: Biomass as a form of energy source may be utilized in two different ways: directly by burning the biomass and indirectly by converting it into solid, liquid or gaseous fuels. Pyrolysis is an indirect conversion method, and can be described in simpler terms as a thermal decomposition of biomass under oxygen-depleted conditions to an array of solid, liquid and gaseous products, namely biochar, bio-oil and fuel gas. However, pyrolysis of biomass is a complex chemical process with several operational and environmental challenges. Consequently, this process has been widely investigated in order to understand the mechanisms and kinetics of pyrolysis at different scales, viz. particle level, multi-phase reacting flow, product distribution and reactor performance, process integration and control. However, there are a number of uncertainties in current biomass pyrolysis models, especially in their ability to optimize process conditions to achieve desired product yields and distribution.

The present contribution provides a critical review of the current status of mathematical modelling studies of biomass pyrolysis with the aim to identify knowledge gaps for further research and opportunities for integration of biomass pyrolysis models of disparate scales. Models for the hydrodynamic behaviour of particles in pyrolysis, and their interaction with the reactive flow and the effect on the performance of the reactors have also been critically analyzed. From this analysis it becomes apparent that feedstock characteristics, evolving physical and chemical properties of biomass particles and residence times of both solid and gas phases in reactors hold the key to the desired performance of the pyrolysis process. Finally, the importance of catalytic effects in pyrolysis has also been critically analyzed, resulting in recommendations for further research in this area especially on selection of catalysts for optimal product yields under varying operating conditions.

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Recycling and recovery routes of plastic solid waste (PSW): A review

Authors: S.M. Al-Salem, P. Lettieri, J. Baeyens
Publication date: July 2009
Source: Waste Management, Volume 29, Issue 10, October 2009, pp 2625-2643
DOI:  https://doi.org/10.1016/j.wasman.2009.06.004
Document Type: Review
Abstract: Plastic solid waste (PSW) presents challenges and opportunities to societies regardless of their sustainability awareness and technological advances. In this paper, recent progress in the recycling and recovery of PSW is reviewed. A special emphasis is paid on waste generated from polyolefinic sources, which makes up a great percentage of our daily single-life cycle plastic products. The four routes of PSW treatment are detailed and discussed covering primary (re-extrusion), secondary (mechanical), tertiary (chemical) and quaternary (energy recovery) schemes and technologies. Primary recycling, which involves the re-introduction of clean scrap of single polymer to the extrusion cycle in order to produce products of the similar material, is commonly applied in the processing line itself but rarely applied among recyclers, as recycling materials rarely possess the required quality. The various waste products, consisting of either end-of-life or production (scrap) waste, are the feedstock of secondary techniques, thereby generally reduced in size to a more desirable shape and form, such as pellets, flakes or powders, depending on the source, shape and usability. Tertiary treatment schemes have contributed greatly to the recycling status of PSW in recent years. Advanced thermo-chemical treatment methods cover a wide range of technologies and produce either fuels or petrochemical feedstock. Nowadays, non-catalytic thermal cracking (thermolysis) is receiving renewed attention, due to the fact of added value on a crude oil barrel and its very valuable yielded products. But a fact remains that advanced thermo-chemical recycling of PSW (namely polyolefins) still lacks the proper design and kinetic background to target certain desired products and/or chemicals. Energy recovery was found to be an attainable solution to PSW in general and municipal solid waste (MSW) in particular. The amount of energy produced in kilns and reactors applied in this route is sufficiently investigated up to the point of operation, but not in terms of integration with either petrochemical or converting plants. Although primary and secondary recycling schemes are well established and widely applied, it is concluded that many of the PSW tertiary and quaternary treatment schemes appear to be robust and worthy of additional investigation.

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Biomass Drying and Dewatering for Clean Heat & Power

Authors: Carolyn J. Roos, Ph.D.
Publication date: September 2008 (Rev.October 2013)
Source: WSU Extension Energy Program
Document Type: White Paper
Abstract: As prices for biomass fuels increase, it is especially important to use them efficiently. In both incineration and gasification, biomass drying increases efficiency and improves operation. This guide provides general information about drying biomass fuels, one element of getting the most out of biomass-fired combined heat and power projects.

Even maintaining a flame in a boiler can be difficult if the fuel is too wet. While some types of gasifiers can tolerate higher moisture contents, most biomass gasifiers require less than 20% moisture content for operation. In addition, biomass often requires pelletization, which may require even lower moisture contents than are required by gasifiers and boilers.

Dryer types used in drying biomass fuels include rotary, conveyor, cascade, and flash dryers. When selecting a dryer and designing a system, it is important to consider many factors in addition to energy efficiency, such as environmental emissions and operation and maintenance concerns. Overall efficiency may be improved by sizing the boiler and dryer together, incorporating other energy efficiency measures, taking advantage of heat recovery from the boiler or gasifier and other waste heat sources in the facility. Dryers and boiler stack economizers can be used in conjunction with each other in some systems to take maximum advantage of recovered heat from the boiler. Heat may also be
recovered from the dryer for use in the facility.

Wet feedstocks can be dewatered prior to drying by drying beds, filters and screens, presses, and centrifuges. Alternatives to thermal drying and dewatering should also be considered. Moist feedstocks might be mixed with drier materials to achieve an acceptable moisture content of the mixture. Some lower moisture feedstocks can be sufficiently dried simply by storing in a covered area and turning periodically. Others, such as rice stalks or sawdust from cabinet shops, do not need drying at all.

As a renewable energy source, biomass-fired energy systems may qualify for financial incentives depending on location. Avoided carbon emissions can also be traded on exchanges such as the Chicago Climate Exchange.

While this guide may be used to begin a preliminary analysis, a professional engineer and other professionals with experience in biomass drying should be consulted for the design of a particular project.

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Physical and mechanical properties of particleboard bamboo waste bonded with urea formaldehyde and castor oil based adhesive

Authors: Ivaldo De Domenico Valarelli, Rosane Ap. Gomes Battistelle, Marcus Antonio Pereira Bueno, Barbara Stolte Bezerra, Cristiane I. de Campos, Manoel C. de S. Alves
Publication date: March 2014
Source: Matéria (Rio J.) vol.19 no.1 Rio de Janeiro Jan./Mar. 2014
DOI: http://dx.doi.org/10.1590/S1517-70762014000100002
Document Type: Research Paper
Abstract: This study evaluated the physical and mechanical characteristics of particleboards made of bamboo waste from the species Dendrocalamus giganteus bonded with two different types of adhesives: urea-formaldehyde (UF) and a castor oil based adhesive (M). Thus, eight types of particleboards were produced in the proportions of 6%, 8%, 10% and 12% for each adhesive. The results showed that particleboards produced with UF and M adhesives had acceptable behavior for physical tests according to the Brazilian standard NBR 14810. The results attained in mechanical tests (MOR and MOE), for all particleboards, were below the requirements for structural usage. This indicates that the residue of bamboo is a feasible raw material alternative for particleboards produced for non structural purposes, such as liners, partitions and other uses for internal seal. Regarding the adhesives, the particleboards produced with UF particleboards showed superior results for both physical and mechanical characteristics, when compared to M particleboards with the same percentage of adhesive.
Keywords: particleboard; recycle materials; composites; adhesives; castor oil based adhesive

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