Dry Tons Research Articles

Effect of corn stover compositional variability on minimum ethanol selling price (MESP)

A techno-economic sensitivity analysis was performed using a National Renewable Energy Laboratory (NREL) 2011 biochemical conversion design model varying feedstock compositions. A total of 496 feedstock near infrared (NIR) compositions from 47 locations in eight US Corn Belt states were used as the inputs to calculate minimum ethanol selling price (MESP), ethanol yield (gallons per dry ton biomass feedstock), ethanol annual production, as well as total installed project cost for each composition. From this study, the calculated MESP is $2.20 ± 0.21 (average ± 3 SD) per gallon ethanol.

Design and simulation of an organosolv process for bioethanol production

Organosolv pulping can be used as a pretreatment step in bioethanol production. In addition to ethanol, organosolv pulping allows for the production of a pure lignin product and other co-products. Based on publicly available information, conceptual process design and simulation model were developed for an organosolv process. The simulation model was used to calculate the mass and energy balances and approximate fossil-based carbon dioxide (CO2) emissions for the process. With a hardwood feed of 2,350 dry metric tons (MT) per day, 459 MT/day (53.9 million gallons per year) of ethanol was produced. This corresponded to a carbohydrate to ethanol conversion of 64 %. The production rates of lignin, furfural, and acetic acid were 310, 6.6, and 30.3 MT/day, respectively. The energy balance indicated that the process was not energy self-sufficient. In addition to bark and organic residues combusted to produce energy, external fuel (natural gas) was needed to cover the steam demand. This was largely due to the energy consumed in recovering the solvent. Compared to a dilute acid bioethanol process, the organosolv process was estimated to consume 34 % more energy. Allocating all emissions from natural gas combustion to the produced ethanol led to fossil CO2 emissions of 13.5 g per megajoule (MJ) of ethanol. The total fossil CO2 emissions of the process, including also feedstock transportation and other less significant emission sources, would almost certainly not exceed the US Renewable Fuel Standard threshold limit (36.5 g CO2/MJ ethanol).

The sustainable harvesting of Ascophyllum nodosum (Fucaceae, Phaeophyceae) in Ireland, with notes on the collection and use of some other brown algae

Ireland has a long history of seaweed utilisation, with accounts of its use as a food dating to at least the twelfth century. Arramara Teoranta (literally “Seagoods Ltd.”) was established by the Irish Government in the late 1940s to continue the long tradition of sustainable seaweed harvesting in the west of Ireland, which began with kelp ash production from kelp kilns around 1700 and which continued sporadically until 1948. Initially, Arramara purchased dried sea rods (Laminaria hyperborea) and kelp fronds (mostly Saccharina latissima) and these were exported for alginate production in Scotland. Kelps were gradually replaced by Ascophyllum nodosum, a perennial wrack found in the intertidal of the North Atlantic and which is particularly common on sheltered shores in the west of Ireland. This wrack has been cut sustainably by hand in Ireland since at least the late 1940s. Figures for annual production from the main purchaser, Arramara, show that 2,000–7,000 dry weight tons (about 8,000–28,000 wet tons) have been cut in Ireland each year from 1964 to date. Whilst exports for alginate production ceased in 2009, 5,000–6,000 dry weight tons are currently being produced for the animal feed, horticulture, aquaculture, and cosmetics markets.

An Assessment of Thailand’s Biofuel Development

The paper provides an assessment of first generation biofuel (ethanol and biodiesel) development in Thailand in terms of feedstock used, production trends, planned targets and policies and discusses the biofuel sustainability issues—environmental, socio-economic and food security aspects. The policies, measures and incentives for the development of biofuel include targets, blending mandates and favorable tax schemes to encourage production and consumption of biofuels. Biofuel development improves energy security, rural income and reduces greenhouse gas (GHG) emissions, but issues related to land and water use and food security are important considerations to be addressed for its large scale application. Second generation biofuels derived from agricultural residues perform favorably on environmental and social sustainability issues in comparison to first generation biofuel sources. The authors estimate that sustainably-derived agricultural crop residues alone could amount to 10.4 × 106 bone dry tonnes per year. This has the technical potential of producing 1.14–3.12 billion liters per year of ethanol to possibly displace between 25%–69% of Thailand’s 2011 gasoline consumption as transportation fuel. Alternatively, the same amount of residue could provide 0.8–2.1 billion liters per year of diesel (biomass to Fischer-Tropsch diesel) to potentially offset 6%–15% of national diesel consumption in the transportation sector.

Implications of land class and environmental factors on life cycle GHG emissions of Miscanthus as a bioenergy feedstock

AbstractReplacement of fossil fuels with sustainably produced biomass crops for energy purposes has the potential to make progress in addressing climate change concerns, nonrenewable resource use, and energy security. The perennial grass Miscanthus is a dedicated energy crop candidate being field tested in Ontario, Canada, and elsewhere. Miscanthus could potentially be grown in areas of the province that differ substantially in terms of agricultural land class, environmental factors and current land use. These differences could significantly affect Miscanthus yields, input requirements, production practices, and the types of crops being displaced by Miscanthus establishment. This study assesses implications on life cycle greenhouse gas (GHG) emissions of these differences through evaluating five Miscanthus production scenarios within the Ontario context. Emissions associated with electricity generation with Miscanthus pellets in a hypothetically retrofitted coal generating station are examined. Indirect land use change impacts are not quantified but are discussed. The net life cycle emissions for Miscanthus production varied greatly among scenarios (−90–170 kg CO2eq per oven dry tonne of Miscanthus bales at the farm gate). In some cases, the carbon stock dynamics of the agricultural system offset the combined emissions of all other life cycle stages (i.e., production, harvest, transport, and processing of biomass). Yield and soil C of the displaced agricultural systems are key parameters affecting emissions. The systems with the highest potential to provide reductions in GHG emissions are those with high yields, or systems established on land with low soil carbon. All scenarios have substantially lower life cycle emissions (−20–190 g CO2eq kWh−1) compared with coal‐generated electricity (1130 g CO2eq kWh−1). Policy development should consider the implication of land class, environmental factors, and current land use on Miscanthus production.

Influence of Input Biomass Conditions and Operational Parameters on Comminution of Short-Rotation Forestry Poplar and Corn Stover Using Neural Networks

Two kinds of biomass, short-rotation forestry (SRF) poplar and corn stover, were milled with a hammer mill at any combination of several levels of moisture content at mill inlet, wH2O = 7–30%, feeding chip size, 20–50 mm, and under varied operational milling conditions, such as the opening sizes of the internal screen, dtarget = 2–5 mm, and the angular velocity of the hammers, 2000–3000 rpm, to determine their influence on the milling energy consumption and the physical properties of the milled product (moisture content, particle size, bulk density, and angle of repose). The use of neural networks allows one to obtain three-dimensional predictive surfaces for each output variable, which describe tendencies and behavior as a function of the milling conditions. The moisture content at the mill inlet and opening sizes of the screen were found to be the key variables in the process. Specific energy requirements per oven dry tonne of about 28 kWh for poplar and 22 kWh for corn stover were obtained with almost dry biomass (wH2O = 7%) and dtarget = 5 mm, but this energy consumption increases 10-fold under opposite conditions, in which screen blocking was promoted by the high moisture content and the small opening sizes. Under these conditions (wH2O ≈ 30% and dtarget = 2 mm), particle drying can remove half of the initial moisture because of the strong increase in residence time of the particle in the mill chamber but also barely 1% under the opposite milling conditions, with low moisture and bigger opening sizes. Additionally, a bulk density increase between 11 and 98% for poplar and between 89 and 360% for corn stover was registered in relation to the previous chipped form and as a function of the milling conditions. With regard to the angle of repose, a higher moisture content and particle size made the handling behavior worse for both biomasses.

Forest-Based Biomass Supply Curves for the United States

Nationwide, county-level supply curves have been estimated for forest-based biomass to evaluate their potential contributions to producing biofuels. This study builds on the estimates of potential supply in the Billion Ton Supply study prepared by the U.S. Department of Agriculture and the U.S. Department of Energy. Forest biomass sources include logging residue, thinnings, other removals, unused mill residue, urban wood waste, and conventionally sourced wood (pulpwood size material). To make the estimates, we assume that lower cost forest biomass will be supplied from integrated harvesting operations that also remove sawlogs and pulpwood. We also assume that such removals can be estimated at the county level in two ways: first, as a portion of recent estimates of logging residues; and second, by simulated thinning operations that use tops, branches, and small trees for biomass. Supply from thinning dense forest stands is assumed to occur over 30 yr. Harvest and stumpage costs are estimated for each of these methods. Final supply estimates for each county assume supply that is half-way between the two estimates. Forest and agricultural biomass supply estimates have been used to indicate that for a cost of $44 per oven dry ton (odt) at forest roadside or farm gate, we could produce produce 20-billion gal of advanced biofuels as called for under the 2007 Energy Independence and Security Act. Forests could provide about 40-million odt to produce 4-billion gal, and agricultural feedstocks could provide about 200-million odt and produce 16-billion gal of biofuel.

Forest Fuel Reduction and Biomass Supply: Perspectives from Southern Private Landowners

Removing excess biomass from fire-hazardous forests can serve dual purposes: enhancing the health and sustainability of forest ecosystems and supplying feedstock for energy production. The physical availability of this biomass is fairly well-known, yet availability does not necessarily translate into actual supply. We assess the perception and behavior of private forestland owners in the southern United States with respect to thinning overstocked forests for bioenergy production. Landowner perception is then integrated with the USDA Forest Service's Fuel Treatment Evaluator to estimate the biomass supply from fuel treatments on non-industrial private timberlands in the region. Due to competing uses for lumber and pulp/paper products, only about one-third of this biomass could be used as bioenergy feedstock. Between 6 and 66% of landowners would consider thinning overstocked forests for bioenergy purposes depending upon whether financial incentives and technical assistance are provided. Accounting for competing uses, landowner willingness, accessibility, and recovery loss, annual feedstock supply from Southern private treatable timberlands is estimated between 0.9- and 11-million dry tonnes (dt). The average production cost is proximately $48/dt. Government cost shares, biomass market development, and technical assistance could significantly stimulate private landowners to procure biomass from fire-hazardous forests while mitigating wildfire risk.

Grand Challenges in Bioenergy and Biofuel Research: Engineering and Technology Development, Environmental Impact, and Sustainability

SPECIALTY GRAND CHALLENGE article Front. Energy Res., 30 September 2013 | https://doi.org/10.3389/fenrg.2013.00004

Input–Output Modeling of Wood-Based Bioenergy Industries in Mississippi

ABSTRACT The southern region of the United States, which includes Mississippi, has abundant forest resources that provide an opportunity to establish a wood-based bioenergy industry in the region. This study estimated the direct, indirect, and induced economic impacts associated with establishment of wood-based bioenergy facilities in Mississippi. Three potential wood-based bioenergy facilities, wood pellets, bio-oil, and methanol-based gasoline, were considered. The requisite cost information pertaining to the construction and operation of selected wood-based bioenergy facilities were obtained from various secondary sources. Construction activities would impact the economy for a shorter period of time. Results showed operation of a wood pellet facility, having an annual production capacity of 75,000 dry tonnes, would contribute 8,282 full- and part-time jobs and US$12 million worth of economic output to the state economy. Likewise, operation of a bio-oil facility, having an annual production capacity of 66,224.5 dry tonnes, would provide 112 new full- and part-time jobs and an economic output of US$13 million. Similarly, an economic output of US$96 million and 795 more full- and part-time jobs would be added to the Mississippi economy by establishing a methanol-based gasoline facility. Clearly, these impacts are likely to draw the attention of policy makers and investors toward developing wood-based bioenergy opportunities in Mississippi.

A kinetic study of acid catalysed hydrolysis of sugar cane bagasse to levulinic acid

There is a significant research effort worldwide to identify attractive chemical conversion routes for lignocellulosic biomass to organic (bulk-)chemicals. This study has focussed on the acid-catalysed hydrolysis of sugar cane bagasse for the production of levulinic acid (LA), a platform chemical used for the synthesis of a variety of materials for applications such as fuel additives and polymer and resin precursors. The objectives of this study were to develop a broadly applicable kinetic model for the acid-catalysed hydrolysis of sugar cane bagasse to LA and to determine the optimum reaction conditions for its production. Systematic kinetic experiments were carried out by varying the reaction temperature between 150 and 200°C, and the sulphuric acid concentration between 0.11 and 0.55M. The highest LA yield was obtained at 150°C and 0.55M H2SO4 at 63mol%, which equates to the production of 194kg of LA from 1 dry tonne of sugar cane bagasse. The kinetic model developed was in good agreement with the experimental data and also with the previous kinetic models developed for cellulose and sugar cane bagasse. Our kinetic model, though developed for the sugar cane bagasse, can be applied over a wide range of hydrolysis reaction conditions for lignocellulosic biomass. Based on the optimisation study carried out using our kinetic model, an empirical equation is proposed to predict the LA yield at a particular temperature and acid concentration.

Techno-economic analysis of monosaccharide production via fast pyrolysis of lignocellulose

The economic feasibility of a facility producing monosaccharides, hydrogen and transportation fuels via fast pyrolysis and upgrading pathway was evaluated by modeling a 2000 dry metric ton biomass/day facility using Aspen Plus®. Equipment sizing and cost were based on Aspen Economic Evaluation® software. The results indicate that monosaccharide production capacity could reach 338 metric tons/day. Co-product yields of hydrogen and gasoline were 23.4 and 141 metric tons/day, respectively. The total installed equipment and total capital costs were estimated to be $210 million and $326 million, respectively. A facility internal rate of return (IRR) of 11.4% based on market prices of $3.33/kg hydrogen, $2.92/gal gasoline and diesel, $0.64/kg monosaccharide was calculated. Sensitivity analysis demonstrates that fixed capital cost, feedstock cost, product yields, and product credits have the greatest impacts on facility IRR. Further research is needed to optimize yield of sugar via the proposed process to improve economic feasibility.

Development of a comprehensive plan for utilization of digester gas moves towards energy self-sufficiency in Chicago, USA

The Metropolitan Water Reclamation District (MWRD) of Greater Chicago's Stickney Water Reclamation Plant (SWRP) anaerobically digests approximately 430 dry tons per day (dtpd) (390 dry metric tons per day) of solids and produces 3.4 million ft(3)/day (96 thousand m(3)/day) of biogas from the anaerobic digesters, making it one of the largest municipal digester gas complexes in the world. Installation of new treatment processes, as well as future increases in flows and loads to the plant, are expected to significantly increase production of biologically degradable sludge and biogas. This paper presents a comprehensive planning study that was completed to identify and evaluate alternatives for utilization of this biogas. The best, sustainable approach was identified, taking into consideration economics, social impacts, and environmental impacts. The model results indicate that the most economically favorable scenario involves installing a cogeneration facility to produce electricity on-site, and operating it in conjunction with the plant's existing boilers to satisfy the heating needs of the plant. This scenario also provides the greatest reduction in GHG offsets at the power plants.

Modeling Biomass Collection and Woods Processing Life-Cycle Analysis*

Abstract A deterministic spreadsheet model developed in an earlier Consortium for Research on Renewable Industrial Materials (CORRIM) project that calculates cost, fuel, and chemical outputs of forest management and harvesting activities was modified to include logic for systems used to recover forest residue. Two illustrative biomass recovery systems with variations were modeled. A system to recover residues after whole-tree harvesting operations was applied to a representative forest stand in the Inland West. Whole-tree chipping in an early thinning was applied to a representative forest stand in the Southeast United States. Emission factors and life-cycle outputs were developed for the systems through the SimaPro v7.3 model using one if its environmental impact methodologies called TRACI2. Most environmental outputs, including global warming potential, had a direct relationship to fuel consumption of the recovery systems. These outputs were subsequently used as inputs to life-cycle analysis in biofuel conversion facilities. Fuel consumption for recovery of residues from the log landing was 8.10, 12.0, and 16.0 liters per bone dry metric ton (BDmT) at haul distances of 48, 97, and 145 km, respectively. Corresponding fuel consumption for whole-tree chipping and hauling at these distances was 10.5, 16.0, and 21.5 liters/BDmT. Shuttling ground residue from the landing for reload and a subsequent long haul of 145 km increased fuel consumption 32 percent over the residue recovery base case. Shuttling loose residue for centralized processing with a long haul distance of 145 km increases fuel consumption by 86 percent over recovery directly from the landing.

Extraction and recovery of pectic fragments from citrus processing waste for co–production with ethanol

AbstractBACKGROUND: Approximately 0.7 − 1 × 106 dry tons of citrus processing waste (CPW) are produced annually in the United States. CPW is sold as animal feed but often the financial return does not exceed the production cost. Polysaccharides comprise 40% of the total dry matter of which pectin is the major component. CPW was steam treated to extract pectin fragments (PFs) as a value added co–product prior to fermentation of other sugars for biofuels production.RESULTS: PFs were extracted in high yields, along with polymeric arabinans, galactans and arabinogalactans. The extracted polysaccharides ranged in size from small oligomers to polymers of ∼700 000 g mol−1. Acidified treatments led to greater fragmentation of water soluble polysaccharides, but did not enhance fragmentation of pectins to small oligomers (> 30 mer). Methylesterified PFs, arabinans and galactans were recovered by ethanol precipitation while demethylesterified PFs were recovered and purified by precipitation with dilute HCl.CONCLUSION: Steam treatment of CPW provides for rapid, efficient fragmentation of protopectin into highly methylesterified PFs that could be recovered by precipitation. The steaming process for preparation of PFs is environmentally friendly. No toxic chemicals are introduced and the remaining CPW can be used in fermentations to produce ethanol and other compounds. © 2012 Society of Chemical Industry

Technoeconomic assessment of lignocellulosic ethanol production via DME (dimethyl ether) hydrocarbonylation

In this study, a new thermochemical route to produce lignocellulosic ethanol based on DME (dimethyl ether) hydrocarbonylation is proposed and economically assessed. The process is designed and evaluated using current kinetic laboratory data for hydrocarbonylation reactions. Only available technologies or those expected to be available in the short term are considered for the process design, which involves biomass pretreatment and gasification (indirect circulating fluidized bed), gas clean-up and conditioning, methanol synthesis, DME production by methanol dehydration and DME hydrocarbonylation. The process is designed to be both energy self-sufficient and electrical energy neutral. For a plant size of 2140 dry tonnes/day of wood chip (500 MWHHV) the minimum selling price of ethanol (for a 10% rate of return and a biomass price of 66 $/dry tonne) ranges from 0.555 to 0.592 USD2010/L of automotive grade ethanol with fixed capital costs between 333 and 352 M USD2010. Energy efficiency of biomass to ethanol ranges from 44.35 to 45.53% (high heating value basis). These results compare favorably with the “state of the art” production of ethanol via biochemical pathway from lignocellulosic biomass, revealing that the DME hydrocarbonylation route is a promising one that could be cost-competitive in the near future.

Performance and energy efficiency of alternative comminution principles: Chipping versus grinding

Comminution is a critical process in biomass supply chains and can be conducted with either chippers or grinders. These machines use different work tools(knives and hammers, respectively) and are applied to different feedstock types, but few studies are available on the inherent differences between the two technologies. A versatile grinder, alternatively equipped with hammers and knives, was studied to investigate the effect of tool type on machine productivity, fuel consumption, and product quality.The machine was powered by an agricultural tractor rigged with a flow meter, a torque meter, and shaft revolution meter for determining fuel consumption, power output, and engine speed. Three different feedstock types were processed: discarded pallets, solid logs, and residues from park maintenance, the latter consisting of branches from ornamental tree and shrub species. Depending on feedstock type, the knife configuration was 30–80% (average 50%) more productive than the hammer configuration and required 15–30% (average 24%) less energy per unit of product. Fuel consumption per dry ton was 30–75% (average 52%) higher for the hammer configuration. That held true for all feedstock types. Product quality was better for the knife configuration, except for park maintenance residues. In general, hammers should be limited to product with severe contamination that prevents the efficient use of knives.

A Productivity and Cost Comparison of Two Systems for Producing Biomass Fuel from Roadside Forest Treatment Residues

Abstract Forest operations generate large quantities of forest biomass residues that can be used for production of bioenergy and bioproducts. However, a significant portion of recoverable residues are inaccessible to large chip vans, making use financially infeasible. New production systems must be developed to increase productivity and reduce costs to facilitate use of these materials. We present a comparison of two alternative systems to produce biomass fuel (i.e., “hog fuel”) from forest residues that are inaccessible to chip vans: (1) forwarding residues in fifth-wheel end-dump trailers to a concentration yard, where they can be stored and then ground directly into chip vans, and (2) grinding residues on the treatment unit and forwarding the hog fuel in high-sided dump trucks to a concentration yard, where it can be stored and then reloaded into chip vans using a front-end loader. To quantify the productivity and costs of these systems, work study data were collected for both systems on the same treatment unit in northern Idaho in July 2009. With standard machine rate calculations, the observed costs from roadside to loaded chip van were $23.62 per bone dry ton (BDT) for slash forwarding and $24.52 BDT−1 for in-woods grinding. Results indicate that for harvest units with conditions similar to the test area, slash forwarding is most appropriate for sites with dispersed residues and long-distance in-woods grinder mobilization. For sites with densely piled roadside residues, in-wood grinding is likely to be a more productive and less costly option for residue recovery.

Economics of Thermochemical Conversion of Crop Residue to Liquid Transportation Fuel

An economic analysis of producing Fischer–Tropsch (FT) liquid fuel such as diesel from crop residue is presented. The process is thermochemical based involving fast pyrolysis and autothermal reforming (ATR) followed by FT synthesis. A spreadsheet for estimating economics is presented, which is simple to use and transparent in its input parameters and its output. Plant sizes of 2000, 10 000, and 35 000 dry metric tons (t) per day were calculated at 8% return on capital to require sales prices (exclusive of tax) of $3.30, $2.40, and $2.06 per gallon (gal), respectively. U.S. tax would add another ∼$0.50/gallon. A biomass feed stock cost of $61.20/dry t was assumed. Capital cost for the 2000 dry t/day plant is estimated to be $M231. These estimates, of course, must be regarded as rough, but they suggest that even without the benefit of imposed regulations liquid fuel derived from biomass could be competitive at current price levels. Sale of char produced in the pyrolysis step for soil amendment as a byproduc...

Techno‐economics for conversion of lignocellulosic biomass to ethanol by indirect gasification and mixed alcohol synthesis

AbstractThis 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 nth‐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. © 2012 American Institute of Chemical Engineers Environ Prog, 2012