scholarly journals Economic implications of moisture content and logging system in forest harvest residue delivery for energy production: a case study

2017 ◽  
Vol 47 (4) ◽  
pp. 458-466 ◽  
Author(s):  
Francisca Belart ◽  
John Sessions ◽  
Ben Leshchinsky ◽  
Glen Murphy
Keyword(s):  
Moisture Content ◽  
Energy Content ◽  
Energy Output ◽  
Mixed Integer ◽  
Forest Harvest ◽  
Element Analysis ◽  
Economic Implications ◽  
Cable Logging ◽  
Harvest Residue

The need for improving the cost effectiveness of forest harvest residue utilization for bioenergy production has been widely recognized. A number of studies show that reducing residue moisture content presents advantages for transportation and energy content. However, previous research has not focused on the relative advantages of in-forest drying depending on the residue characteristics from different logging systems, comminution, and equipment mobilization. Residue drying curves were developed using finite element analysis for two primary Pacific Northwest logging systems. These curves were applied to a case study in Oregon in which mixed integer mathematical programming was used to optimize residue delivery to a hypothetical co-generation plant with a generating capacity of 6 megawatt-hours (MWh). Assuming that rear-steered trailers can access cable logging units, approximately 98% of the harvest residue generated by cable logging was delivered to the plant, compared with only 56% of residue generated with a ground-based system, mainly because collection costs incurred with ground-based system residues exceed cost benefits of drier material. By considering the energy content of drier residues, the amount of oven-dried metric tonnes (ODMT) needed to supply the plant can be reduced by 16% without affecting the energy output over a 24-month planning horizon. Lower ODMT demand and shifting to drier material decreases the overall production cost by 20.4%.

Economic implications of grinding, transporting, and pretreating fresh versus aged forest residues for biofuel production

2017 ◽  
Vol 47 (2) ◽  
pp. 269-276 ◽  
Author(s):  
Rene Zamora-Cristales ◽  
John Sessions ◽  
Gevan Marrs
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Economic Effect ◽  
Transportation Cost ◽  
Biofuel Production ◽  
Forest Residues ◽  
Forest Harvest ◽  
Economic Implications ◽  
Harvest Residues ◽  
The Difference

The moisture content in forest harvest residues is a key factor affecting the supply cost for bioenergy production. Fresh harvest residues tend to contain higher amounts of water, thus making transportation inefficient. Additionally, fresh harvest residues contain greater amounts of needles and bark that may reduce the polysaccharide content, thus affecting the production of liquid fuels derived from cellulosic components. In this study, we estimated the downstream economic effect in the supply chain of collecting, grinding, transporting and pretreating fresh versus aged residues. Specifically, we analyzed the effect of feedstock moisture content on grinder fuel consumption, bulk density, bark and needle content, and polysaccharide proportion. Fresh forest harvest residues were 60% moisture content (wet basis) and aged forest residues were 15% moisture content. The bark and needle proportion is 6.1% higher in fresh residue than in aged residue. Polysaccharides were 26% higher in aged residue than in fresh residue. On a dry-tonne basis, the cost of grinding fresh residues was about the same as that of aged residues. However, considering the difference in bulk density on transportation cost and the difference in polysaccharide yield, the value gain for in-field drying ranges from US$29.60 to US$74.90 per ovendry tonne.

scholarly journals Finite Element Analysis to Predict In-Forest Stored Harvest Residue Moisture Content

2017 ◽  
Vol 63 (4) ◽  
pp. 362-376 ◽  
Author(s):  
Francisca Belart ◽  
Ben Leshchinsky ◽  
John Sessions
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Moisture Content ◽  
Element Analysis ◽  
Harvest Residue

Initial Development of Optimum Biomass Pellets

2011 ◽  
Author(s):  
Kyle Eggerstedt ◽  
Xia Wang ◽  
James Leidel ◽  
Krzytoff Kobus
Keyword(s):  
Activation Energy ◽  
Moisture Content ◽  
Energy Content ◽  
Combustion Process ◽  
Ash Content ◽  
Energy Output ◽  
Initial Development ◽  
Beet Pulp ◽  
Multiple Materials ◽  
Biomass Particles

Renewable energy has become a major focus in today’s world of depleting energy resources. Biomass is starting to be utilized because it can be continually created within a reasonable period of time. Biomass particles are pressurized together in a pellet shape. The pellets are fed into a combustion chamber (stove) and burnt to create energy. The objective of this research is to test a range of pellet compositions and investigate their corresponding characteristics in the combustion process in order to maximize their energy output. The pellets investigated include single materials such as wood or various mixtures such as wood and grass. The pellets were tested to check the various criteria including the moisture content, density and energy content. Moisture content was found using a scale and desiccators. A thermogravimetric analyzer (TGA) was used to determine the burning temperature of biomass, its weight composition and ash content. A calorimeter was used to find energy content. The Coats-Redfern Method along with a TGA was chosen for the analysis of the activation energy of biomass pellets. Among four types of pellets tested, the hardwood premium pellets has the lowest ash content of .66%. Premium Pellets also had the best energy content of 19.16 MJ/kg. Beet Pulp Pellets had the lowest activation energy of all the materials with 99.92 kJ/mol activation energy. Overall the hardwood pellets performed the best but could be improved with the addition of other biomasses. An optimum pellet may be created with a mixture of multiple materials.

scholarly journals Behavior of Offshore Pile in Calcareous Sand—Case Study

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady
Keyword(s):  
Load Capacity ◽  
High Stress ◽  
Embedment Depth ◽  
Shear Stresses ◽  
Northern Coast ◽  
Compression Tests ◽  
Calcareous Sand ◽  
Element Analysis ◽  
Mixing Ratios

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt's northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

scholarly journals Bi-objective design-for-control of water distribution networks with global bounds

2021 ◽  
Author(s):  
Aly-Joy Ulusoy ◽  
Filippo Pecci ◽  
Ivan Stoianov
Keyword(s):  
Water Distribution ◽  
Distribution Networks ◽  
Water Distribution Networks ◽  
Mixed Integer ◽  
Global Optimality ◽  
Linear Programs ◽  
Design For Control ◽  
Non Linear ◽  
Feasible Solutions

AbstractThis manuscript investigates the design-for-control (DfC) problem of minimizing pressure induced leakage and maximizing resilience in existing water distribution networks. The problem consists in simultaneously selecting locations for the installation of new valves and/or pipes, and optimizing valve control settings. This results in a challenging optimization problem belonging to the class of non-convex bi-objective mixed-integer non-linear programs (BOMINLP). In this manuscript, we propose and investigate a method to approximate the non-dominated set of the DfC problem with guarantees of global non-dominance. The BOMINLP is first scalarized using the method of $$\epsilon $$ ϵ -constraints. Feasible solutions with global optimality bounds are then computed for the resulting sequence of single-objective mixed-integer non-linear programs, using a tailored spatial branch-and-bound (sBB) method. In particular, we propose an equivalent reformulation of the non-linear resilience objective function to enable the computation of global optimality bounds. We show that our approach returns a set of potentially non-dominated solutions along with guarantees of their non-dominance in the form of a superset of the true non-dominated set of the BOMINLP. Finally, we evaluate the method on two case study networks and show that the tailored sBB method outperforms state-of-the-art global optimization solvers.

Autothermal biodrying of municipal solid waste with high moisture content

2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Agnieszka Zawadzka ◽  
Liliana Krzystek ◽  
Stanisław Ledakowicz
Keyword(s):  
Moisture Content ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Energy Content ◽  
Plastic Material ◽  
Initial Moisture Content ◽  
Tubular Reactor ◽  
Calorific Value ◽  
High Energy ◽  
Total Capacity

AbstractTo carry out autothermal drying processes during the composting of biomass, a horizontal tubular reactor was designed and tested. A biodrying tunnel of the total capacity of 240 dm3 was made of plastic material and insulated with polyurethane foam to prevent heat losses. Municipal solid waste and structural plant material were used as the input substrate. As a result of autothermal drying processes, moisture content decreased by 50 % of the initial moisture content of organic waste of about 800 g kg−1. In the tested cycles, high temperatures of biodried waste mass were achieved (54–56°C). An appropriate quantity of air was supplied to maintain a satisfactory level of temperature and moisture removal in the biodried mass and high energy content in the final product. The heat of combustion of dried waste and its calorific value were determined in a calorimeter. Examinations of pyrolysis and gasification of dried waste confirmed their usefulness as biofuel of satisfactory energy content.

Notch-based speed trajectory optimisation for high-speed railway automatic train operation

2021 ◽  
pp. 095440972110421
Author(s):  
Minling Feng ◽  
Chaoxian Wu ◽  
Shaofeng Lu ◽  
Yihui Wang
Keyword(s):  
High Speed ◽  
Applied Force ◽  
Mixed Integer ◽  
High Speed Railway ◽  
Train Operation ◽  
Train Speed ◽  
Automatic Train Operation ◽  
The Impact ◽  
Trajectory Optimisation

Automatic train operation (ATO) systems are fast becoming one of the key components of the intelligent high-speed railway (HSR). Designing an effective optimal speed trajectory for ATO is critical to guide the high-speed train (HST) to operate with high service quality in a more energy-efficient way. In many advanced HSR systems, the traction/braking systems would provide multiple notches to satisfy the traction/braking demands. This paper modelled the applied force as a controlled variable based on the selection of notch to realise a notch-based train speed trajectory optimisation model to be solved by mixed integer linear programming (MILP). A notch selection model with flexible vertical relaxation was proposed to allow the traction/braking efforts to change dynamically along with the selected notch by introducing a series of binary variables. Two case studies were proposed in this paper where Case study 1 was conducted to investigate the impact of the dynamic notch selection on train operations, and the optimal result indicates that the applied force can be flexibly adjusted corresponding to different notches following a similar operation sequence determined by optimal train control theory. Moreover, in addition to the maximum traction/braking notches and coasting, medium notches with appropriate vertical relaxation would be applied in accordance with the specific traction/braking demands to make the model feasible. In Case study 2, a comprehensive numerical example with the parameters of CRH380AL HST demonstrates the robustness of the model to deal with the varying speed limit and gradient in a real-world scenario. The notch-based model is able to obtain a more realistic optimal strategy containing dynamic notch selection and speed trajectory with an increase (1.622%) in energy consumption by comparing the results of the proposed model and the non-notch model.

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