The 2011 US Billion‐Ton Update 1 estimates that there are enough agricultural and forest resources to sustainably provide enough biomass to displace approximately 30% of the country's current petroleum consumption. A portion of these resources are inaccessible at current cost targets with conventional feedstock supply systems because of their remoteness or low yields. Reliable analyses and projections of US biofuels production depend on assumptions about the supply system and biorefinery capacity, which, in turn, depend on economics, feedstock logistics, and sustainability. A cross‐functional team has examined optimal combinations of advances in feedstock supply systems and biorefinery capacities with rigorous design information, improved crop yield and agronomic practices, and improved estimates of sustainable biomass availability. Biochemical‐conversion‐to‐ethanol is analyzed for conventional bale‐based system and advanced uniform‐format feedstock supply system designs. The latter involves ‘pre‐processing’ biomass into a higher‐density, aerobically stable, easily transportable format that can supply large‐scale biorefineries. Feedstock supply costs, logistics and processing costs are analyzed and compared, taking into account environmental sustainability metrics. © 2013 Society of Chemical Industry and John Wiley & Sons Ltd

The objective of this project is to establish a tiered Technology to Market (T2M) curriculum for basic researchers to project leads to measure the effect of technology transfer skills on project success and impact. The plan will train five researchers in basic technology transfer principles where success will be measured by assessing improvements in T2M skills and knowledge after the training is complete, likely using before and after surveys.

Characterize high and low moisture waste biomass samples found and retrieved from the Box Elder County, Utah region that could be used in an anaerobic digestion process. Combine the analysis coordinated by INL with information available in the literature to generate a report for Procter & Gamble on chemical characteristics of waste materials available in Box Elder County, Utah for use in anaerobic digestion.

P&G intends to replace as much as their current heat and power by renewable energy sources. For 2014, P&G’s total energy including electricity, natural gas and steam is approximately 1,540,000 MMBTU annually (Table 2). The biomass and wastes around P&G facility can be grouped into six categories (Figure 6): (1) Agriculture residue and grass, (2) Refuse (inorganic) solid material, (3) Food waste, (4) Organic waste stream, (5) livestock manure, (6) wastewater and sludge. The six feedstock sources can provide a total energy of 3,520,000 MMBTU per year (Table 10), among which the agriculture residue is the biggest fraction, about 67%, followed by livestock manures 27%. Therefore, the available energy sources around P&G facility are enough to meet their energy needs. These energy feedstocks would be treated by two processes: anaerobic digestion for biogas subsequently for heat and power and thermochemical process (combustion, pyrolysis and gasification) for heat and power (Figure 8 and 9). For AD, a one-stage complete mixing digester is preferable; and fluidized bed reactors are favorable for thermochemical process.

The development of a U.S. bioenergy market and ultimately ‘bioeconomy’ has primarily been investigated with a national focus. Limited attention has been given to the potential impacts of international market developments. The goal of this project is to advance the current State of Technology of a single biorefinery to the global level providing quantitative estimates on how international markets may influence the domestic feedstock supply costs. The scope of the project is limited to feedstock that is currently available and new crops being developed to be used in a future U.S. bioeconomy including herbaceous residues (e.g., corn stover), woody biomass (e.g., pulpwood), and energy crops (e.g., switchgrass). The timeframe is set to the periods of 2022, 2030, and 2040 to align with current policy targets (e.g., the RFS2) and future updates of the Billion Ton data. This particular milestone delivers demand volumes for generic woody and herbaceous feedstocks for the main (net) importing regions along the above timeframes. The regional focus of the study is the European Union (EU), currently the largest demand region for U.S. pellets made from pulpwood and forest residues. The pellets are predominantly used in large-scale power plants (>5MWel) in the United Kingdom (UK), the Netherlands (NL), Belgium (BE), and Denmark (DK).

followed by livestock manures 27%. Therefore, the available energy sources around P&G facility are enough to meet their energy needs. These energy feedstocks would be treated by two processes: anaerobic digestion for biogas subsequently for heat and power and thermochemical process (combustion, pyrolysis and gasification) for heat and power (Figure 8 and 9). For AD, a one-stage complete mixing digester is preferable; and fluidized bed reactors are favorable for thermochemical process.

This paper analyzes the rural Chinese biomass supply system and models supply chain operations according to U.S. concepts of logistical unit operations: harvest and collection, storage, transportation, preprocessing, and handling and queuing. In this paper, we quantify the logistics cost of corn stover and sweet sorghum in China under different scenarios. We analyze three scenarios of corn stover logistics from northeast China and three scenarios of sweet sorghum stalks logistics from Inner Mongolia in China. The case study estimates that the logistics cost of corn stover and sweet sorghum stalk to be $52.95/dry metric ton and $52.64/dry metric ton, respectively, for the current labor-based biomass logistics system. However, if the feedstock logistics operation is mechanized, the cost of corn stover and sweet sorghum stalk decreases to $36.01/dry metric ton and $35.76/dry metric ton, respectively. The study also includes a sensitivity analysis to identify the cost factors that cause logistics cost variation. Results of the sensitivity analysis show that labor price has the most influence on the logistics cost of corn stover and sweet sorghum stalk, with a variation of $6 to $12/dry metric ton.

Background: Mechanical preprocessing, which includes particle-size reduction and mechanical separation, is one of the primary operations in the feedstock supply system for a lignocellulosic biorefinery. It is the means by which raw biomass from the field or forest is mechanically transformed into an on-spec feedstock with characteristics better suited for the fuel conversion process. Results: This work provides a general overview of the objectives and methodologies of mechanical preprocessing and then presents experimental results illustrating improved size reduction via optimization of hammer mill configuration, improved size reduction via pneumatic-assisted hammer milling and improved control of particle size and particle-size distribution through proper selection of grinder process parameters. Conclusion: Optimal grinder configuration for maximal process throughput and efficiency is strongly dependent on feedstock type and properties, such as moisture content. Tests conducted using a HG200 hammer grinder indicate that tip speed, screen size and optimizing hammer geometry can increase grinder throughput as much as 400%.

The United States has an abundant potential of biomass resources that can be used as bioenergy feedstocks; however, biomass in its raw, “as-harvested” form is not necessarily in a format (low bulk density and high moisture content) that meets the needs for the biofuel or bioenergy industry. Both high production and niche crops must be used together to meet the U. S. Department of Energy (DOE)’s goal to supply 36 billion gallons of renewable transportation fuels by 2022. To reach this goal, the United States must use more than just the common biomass sources such as corn stover, switchgrass, and other high production energy crops; it must also find ways to combine additional feedstocks as well. This study shows that the formulation of mixed feedstocks using niche and high production crops can produce feedstocks that meet the uniform format required by industry. Corn stover, switchgrass, lodgpole pine, and eucalyptus were combined during preprocessing followed by densification into pellets, resulting in a denser, higher energy value, more durable feedstock than the average of these fuels individually. This study also compares the energy consumption involved in preprocessing biomass. In the case of grinding energies for both Stage-I and Stage-II processes, corn stover and switchgrass consumed the least at about 19 and 34 kW hr/ton and 11 and 18 kW hr/ton, respectively, whereas the highest was both woody biomass types at about 94 and 43–49 kW hr/ton. The bulk density of pelletized blended feedstock is about 729 kg/m3 and is higher than what corn stover and switchgrass pelletized individually can achieve. The heating values are highest for woody biomass at about 18.37–19.30 MJ/kg and lowest for corn stover and switchgrass, which were both in the range of 16.74–16.97 MJ/kg. From these results, we can conclude that the physical and energy properties of blended feedstocks are better than just individually pelletized herbaceous biomass.

There is a growing interest internationally to use more biomass for power generation, given the potential for significant environmental benefits and long-term fuel sustainability. However, the use of biomass alone for power generation is subject to serious challenges, such as feedstock supply reliability, quality, and stability, as well as comparative cost, except in situations in which biomass is locally sourced. In most countries, only a limited biomass supply infrastructure exists. Alternatively, co-firing biomass along with coal offers several advantages; these include reducing challenges related to biomass quality, buffering the system against insufficient feedstock quantity, and mitigating the costs of adapting existing coal power plants to feed biomass exclusively. There are some technical constraints, such as low heating values, low bulk density, and grindability or size-reduction challenges, as well as higher moisture, volatiles, and ash content, which limit the co-firing ratios in direct and indirect co-firing. To achieve successful co-firing of biomass with coal, biomass feedstock specifications must be established to direct pretreatment options in order to modify biomass materials into a format that is more compatible with coal co-firing. The impacts on particle transport systems, flame stability, pollutant formation, and boiler-tube fouling/corrosion must also be minimized by setting feedstock specifications, which may include developing new feedstock composition by formulation or blending. Some of the issues, like feeding, co-milling, and fouling, can be overcome by pretreatment methods including washing/leaching, steam explosion, hydrothermal carbonization, and torrefaction, and densification methods such as pelletizing and briquetting. Integrating formulation, pretreatment, and densification will help to overcome issues related to physical and chemical composition, storage, and logistics to successfully co-fire higher percentages of biomass (>40%) with coal.

Equipment manufacturers have made rapid improvements in biomass harvesting and handling equipment. These improvements have increased transportation and handling efficiencies due to higher biomass densities and reduced losses. Improvements in grinder efficiencies and capacity have reduced biomass grinding costs. Biomass collection efficiencies (the ratio of biomass collected to the amount available in the field) as high as 75% for crop residues and greater than 90% for perennial energy crops have also been demonstrated. However, as collection rates increase, the fraction of entrained soil in the biomass increases, and high biomass residue removal rates can violate agronomic sustainability limits. Advancements in quantifying multi-factor sustainability limits to increase removal rate as guided by sustainable residue removal plans, and mitigating soil contamination through targeted removal rates based on soil type and residue type/fraction is allowing the use of new high efficiency harvesting equipment and methods. As another consideration, single pass harvesting and other technologies that improve harvesting costs cause biomass storage moisture management challenges, which challenges are further perturbed by annual variability in biomass moisture content. Monitoring, sampling, simulation, and analysis provide basis for moisture, time, and quality relationships in storage, which has allowed the development of moisture tolerant storage systems and bestmore » management processes that combine moisture content and time to accommodate baled storage of wet material based upon “shelf-life.” The key to improving biomass supply logistics costs has been developing the associated agronomic sustainability and biomass quality technologies and processes that allow the implementation of equipment engineering solutions.« less

This research studied the effects of torrefaction temperature (250-250 degrees C) and time (30-120 minutes) on elemental composition and energy properties changes in corn stover. Torrefied material was analyzed for moisture content, moisture-free carbon (%), hydrogen (%), nitrogen (%), sulfur (%), and higher heating value (MJ/kg). Results at 350 degrees C and 120 minutes indicated a steep decrease in moisture content to a final value of about 1.48%-a reduction of about 69%. With respect to carbon content, the increase was about 23%, while hydrogen and sulfur content decreased by about 46.82% and 66.6%, respectively. The hydrogen-to-carbon ratio decreased as torrefaction temperature and time increased, with the lowest value of 0.6 observed at 350 degrees C and 120 minutes. Higher heating value measured at 350 degrees C and 60 minutes increased by about 22% and the maximum degree of carbonization observed was about 1.21. Further, the regression models developed for chemical composition in terms of torrefaction temperature and time adequately described the process with coefficient of determination values (R-2) in the range of 0.92-0.99 for the elemental composition and energy properties studied. Response surface plots indicated that increasing both torrefaction temperature and time resulted in decreased moisture content, hydrogen content, and the hydrogen to-carbon ratio, and increased carbon content and higher heating value. This effect was more significant at torrefaction temperatures and times >280 degrees C and >30 minutes.

A conventional bale feedstock design has been established that represents supply system technologies, costs, and logistics that are achievable today for supplying herbaceous feedstocks as a blendstock with coal for energy production. Efforts are made to identify bottlenecks and optimize the efficiency and capacities of this supply system, within the constraints of existing local feedstock supplies, equipment, and permitting requirements. The feedstock supply system logistics operations encompass all of the activities necessary to move herbaceous biomass feedstock from the production location to the conversion reactor ready for blending and insertion. This supply system includes operations that are currently available such that costs and logistics are reasonable and reliable. The system modeled for this research project includes the uses of field-dried corn stover or switchgrass as a feedstock to annually supply an 800,000 DM ton conversion facility.

Gas chromatography (GC) is a common method used to analyze gases produced during various chemical processes. Torrefaction, for example, is a method for pretreating biomass to make it more suitable for bioenergy applications that uses GC to characterize products formed during the process. During torrefaction, biomass is heated in an inert environment to temperatures ranging between 200–300°C. Torrefaction causes biomass to lose low-energy condensables (liquids) and non-condensable volatiles, initially in gas form, thereby making biomass more energy dense.

This techno-economic study investigates the production of ethanol and a higher alcohols coproduct by conversion of lignocelluosic biomass to syngas via indirect gasification followed by gas-to-liquids synthesis over a precommercial heterogeneous catalyst. The design specifies a processing capacity of 2,205 dry U.S. tons (2,000 dry metric tonnes) of woody biomass per day and incorporates 2012 research targets from NREL and other sources for technologies that will facilitate the future commercial production of cost-competitive ethanol. Major processes include indirect steam gasification, syngas cleanup, and catalytic synthesis of mixed alcohols, and ancillary processes include feed handling and drying, alcohol separation, steam and power generation, cooling water, and other operations support utilities. The design and analysis is based on research at NREL, other national laboratories, and The Dow Chemical Company, and it incorporates commercial technologies, process modeling using Aspen Plus software, equipment cost estimation, and discounted cash flow analysis. The design considers the economics of ethanol production assuming successful achievement of internal research targets and n(th)-plant costs and financing. The design yields 83.8 gallons of ethanol and 10.1 gallons of higher-molecular-weight alcohols per U.S. ton of biomass feedstock. A rigorous sensitivity analysis captures uncertainties in costs and plant performance. (C) 2012 American Institute of Chemical Engineers Environ Prog, 31: 182-190, 2012

Energy from biomass is considered carbon-neutral because the carbon dioxide released during its use is already part of the carbon cycle. Increasing the use of biomass for energy can help to reduce the negative CO2 impact on the environment. There are many challenges in using biomass for energy applications, such as low bulk density, high moisture content, irregular size and shape, hydrophilic nature, and low calorific value. In commercial scale operations where large quantities of biomass are needed, these limitations will create problems associated with storage and transportation. Furthermore, grinding raw biomass with high moisture content is very challenging as there is no specific equipment, which can increase costs, and in some cases becomes highly impossible. All of these drawbacks led to the development of some pretreatment techniques to make biomass more suitable for fuel applications. One of these is torrefaction. Torrefaction is the heating of biomass in an inert or reduced oxygen environment. During torrefaction, biomass losses moisture, becomes more brittle, and increases energy density values. Several technologies exist for the torrefaction of biomassfixed bed, bubbling sand bed, screw extruder, and moving bed are the most commonly used. The use of microwaves for the torrefaction of biomass has not been explored at present. In the present study, we looked into the torrefaction of biomass using the established methods as well as by using microwaves and their effect on proximate and ultimate composition. Studies indicated that microwave torrefaction is a good way to pretreat the biomass in short periods of time. A maximum calorific value of 21 MJ/kg is achievable at 6 min residence time as compared to 15 min using the dry torrefaction technique. Increasing the residence time also increased the carbon content where a maximum carbon content of 52.20% was achievable at a lower residence time. The loss of volatiles is comparatively lower as compared to the dry torrefaction technique. Moisture content of microwave torrefied samples was in between 22.5% (w.b).

Torrefaction tests on miscanthus and white oak sawdust were conducted in a bubbling sand bed reactor to see the effect of temperature and residence time on the chemical composition. Process conditions for miscanthus and white oak sawdust were 250–350 °C for 30–120 min and 220–270 °C for 30 min, respectively. Torrefaction of miscanthus at 250 °C and a residence time of 30 min resulted in a significant decrease in moisture—about 82.68%—but the other components—hydrogen, nitrogen, sulfur, and volatiles—changed only marginally. Increasing torrefaction temperatures to 350 °C with a residence time of 120 min further reduced the moisture content to 0.54%, with a significant decrease in the hydrogen, nitrogen, and volatiles by 58.29%, 14.28%, and 70.45%, respectively. Regression equations developed for the moisture, hydrogen, nitrogen, and volatile content of the samples with respect to torrefaction temperature and time have adequately described the changes in chemical composition based on R2 values of >0.82. Surface plots based on the regression equation indicate that torrefaction temperatures of 280–350 °C with residence times of 30–120 min can help reduce moisture, nitrogen, and volatile content from 1.13% to 0.6%, 0.27% to 0.23%, and 79% to 23%, with respect to initial values. Trends of chemical compositional changes in white oak sawdust are similar to miscanthus. Torrefaction temperatures of 270 °C and a 30 min residence time reduced the moisture, volatiles, hydrogen, and nitrogen content by about 79%, 17.88%, 20%, and 5.88%, respectively, whereas the carbon content increased by about 3.5%.

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Transportation can be a prohibitive cost in bringing biomass to a preprocessing location or biofuel refinery. One alternative to transporting biomass in baled or loose format to a preprocessing location is to utilize a mobile preprocessing system that can be relocated to the places where biomass is stored and used to preprocess and densify the biomass, which is then shipped to the refinery as needed. Idaho National Laboratory (INL) has a full-scale process demonstration unit (PDU) that includes a Stage 1 grinder, hammer mill, drier, pellet mill, and cooler with the associated conveyance system components. Testing at bench and pilot scales has been conducted to determine effects of moisture on preprocessing, crop varieties on preprocessing efficiency, and product quality. INLs PDU provides an opportunity to test the conclusions made at the bench and pilot scales on full industrial-scale systems. Each PDU component is operated from a central operating station where data is collected to determine power consumption rates for each step in the process. The power for each electrical motor in the system is monitored from the control station for problems and to determine optimal conditions for system performance. The data can then be evaluated to determine how changes in biomass input parameters (for example, moisture and crop type), mechanical changes (i.e., screen size, biomass drying, pellet size, grinding speed, etc.), or other variations affect the power consumption of the system. Sorgum, in four-foot round bales, was tested in the system using a series of six different screen sizes, including 3/16 in., 1 in., 2 in., 3 in., 4 in., and 6 in. The effect on power consumption, product quality, and production rate were measured to determine optimal conditions.