Importance of capital cost reduction of chippers and their required productivity

The productivity and chipping cost of a low-investment small mobile chipper were investigated. The effect of capital cost on chipping cost reduction was analyzed by changing the service life of the chipper when assuming a target operational chipping cost set at 250 yen m^?3. Productivity of the investigated chipper was found to be at 23.7 m³ h^?1 in chip volume with fuel consumption at 14.6 L h^?1. The results showed that the chipping cost of the investigated chipper was lower than that of a higher priced and more productive grinder. Neither chipper nor grinder, however, could achieve the assumed target cost of 250 yen m^?3 even if their service lives were extended. It was necessary to withstand the initial grapple loader and the labor costs or raise the grinder’s productivity to 33 m³ h^?1 in order to reach a comparable operational cost target with that of the investigated chipper. Similarly, the grinder would have to reduce its capital cost and fuel consumption to maintain the chipping cost of 250 yen m^?3 ifproductivity could not be improved. Net chipping cost of the investigated chipper was relatively small compared to that of the tub grinder, especially under a shorter service lifespan. The investigation shows that it is feasible for small-scale forestry to introduce a low-investment mobile chipper because it does not require a large amount of material and has a low chipping cost. Moreover, lowering the capital cost or the price of chippers is a more realistic cost savings in the long term.     

Simulation of stump crushing and truck transport of chips

Abstract

The use of stumps for energy production has grown rapidly in Finland and is also commencing in Sweden, the UK and a number of other countries. Practically all stumps are comminuted either at the plant or at terminals, whereas a major part of small-diameter trees and logging residues is chipped at roadside landing. Until now, crushing of stumps has been done with heavy, often stationary, crushers. In smaller plants, construction of a stationary crusher is not economically feasible. In addition, transportation of stumps calls for special trucks, while economical transport distances are short owing to the small payload. Recently, effective mobile crushers suitable for the comminution of stumps, that can also operate as mobile chippers for logging residue and small-diameter trees, have been introduced. They move from landing to landing with the crushed material transported to the end-user by trucks. In this study a discrete-event simulation model was programmed to find optimal set-ups for the supply chain of crushed material made from stumps at different road transport distances. The simulation model was based on the continuous supply of crushed material from landings to a district heating plant. Transportation distances varied from 20 to 120 km, while the number of trucks varied from one to four. It was found that already at 20 km the use of two chip trucks is competitive and after 40 km a third truck should be introduced into the system. Beyond 100 km four trucks would be needed. The results were compared with those obtained from a static spreadsheet model. The static model underestimated the waiting cost in the situation where the productivity of crushing and truck transport was almost balanced.     

自行式剥皮削片联合机的设计

研究并设计了一种适用于林区的自行式剥皮削片联合机,其主要由行走、剥皮、削片和辅助支撑等装置组成,通过柴油发电机提供动力,满足进给、剥皮与削片的动力要求。该机能适应林区生产环境,可就地将小径材及采伐剩余物加工成不含树皮的优质木片,既节省了人工,又降低了运输成本。     

A model to predict productivity of different chipping operations

The chipping operation is an important component of harvesting systems producing biomass and pulp chips. This paper aimed to develop a valid model to predict the productivity of chipping as part of these operations. Over a number of years more than 200 different time studies were conducted on chipping operations in Italy and Australia. Multiple regressions and backward stepwise data analysis methods were applied to develop a productivity prediction equation, considering the following variables: machine power (kW), piece size (m³), crew size, harvesting method, species, tree part, wood condition, wood lay-out, chipping type, propulsion, feeding method, point of chipping, season, location of chip discharge, country (Italy or Australia) and type of operation (biomass chip operation or pulp chip operation). The final productivity model included machine power, average piece size, location of chip discharge and type of operation as significant variables. The internal validation test was conducted using five witness samples from Italy and Australia, which confirmed the validity at α=0.05. Additional international case studies from North America, South America, and central and northern Europe were used to test the accuracy of the model, in which 15 studies confirmed the model's validity and two failed to pass the test.     

Energy Audit of Wood Harvesting Systems

A computer-based model for the evaluation of energy use in mechanized wood harvesting systems (EnergyCalc) was developed with aid of life cycle analysis methodologies. The system boundaries were determined "from stump to roadside" with wood volume over bark (m³) as the functional unit. The computer model (based on a database system) used a Visual Basic program, and the energy audit was based on fuel and oil consumption, and the energy consumed in the manufacture of the machines and replacement parts. The general scenario from the literature, results from Sweden and a preliminary study from Ireland are presented. In the overall energy audit of mechanized wood harvesting systems in Ireland, fuel consumption was the most significant item (82%), followed by oils (7%) and machine repairs and replacement (11%). The mean energy use from the data for Ireland was found to be 16% higher than the equivalent in Sweden (120 vs 103 MJ m^?3). An energy reduction strategy that has the potential to reduce overall energy consumption for Irish systems by up to 13% was suggested.     

Co-operative forest fuel procurement strategy and its saving effects on overall transportation costs

Abstract

Minimum procurement cost is an essential element for the competitiveness of the forest fuel supply chain. This paper compares one co-operative procurement strategy with several non-co-operative strategies by measuring the cost gap. For a study region consisting of five Austrian provinces, forest fuel supply potential and transportation costs were investigated concerning 28 newly built combined heat and power (CHP) plants. In the case of co-operation, the minimum total transportation cost was derived by solving the corresponding transportation problem. In non-co-operative supply chains, CHP plants compete for forest fuel. This case was illustrated by analysing three different clearly non-co-operative procurement strategies, because CHP plants guard their real supply sources as business secrets. The minimum procurement cost for all CHP plants is provided by the co-operative strategy. It comprises a total transportation cost of €17 million and an average procurement distance of 122 km. Co-operation between CHP plants lowers forest fuel transportation costs by 23% on average and reduces average transportation distances by 26%. The resultant cost-cutting potential stresses the importance of co-operation between CHP plants in order to allocate forest fuel supplies efficiently. Establishing partnerships and working alliances for forest fuel procurement therefore has important management implications for achieving efficiency in forest fuel supplies and strengthening the competitiveness of wood-fuel-based energy production.     

Stochastic simulation of forest fuel sourcing models under risk

Abstract

Climate change effects such as storms and droughts are leading to increased risk of forest damage in central Europe. The aim of this paper was to evaluate forest fuel sourcing models including climate change-induced risks on forest fuel supply. Stochastic risk events, such as storms and bark beetle infestations, were modelled by means of a Monte Carlo simulation, and the economic performance was evaluated for two fuel-sourcing models supplying a single combined heat and power plant (CHP). The first sourcing model depicted a common sourcing model for Austrian CHPs, where only forest chips provided by long- and short-term suppliers were stored. The second sourcing model additionally enabled the storage of salvaged pulpwood to supply forest fuel from the plant's own inventory during shortage periods. Simulation results showed that storing salvage pulpwood as feedstock considerably reduced supply chain risks and resulted in lower procurement costs (1–3% less than normal delivered cost without storing salvaged pulpwood).     

Fuels and fire behavior in chipped and unchipped plots: Implications for land management near the wildland/urban interface

Fire behavior was measured and modeled from eight 1 ha experimental plots located in the Francis Marion National Forest, South Carolina, during prescribed burns on February 12 and February 20, 2003. Four of the plots had been subjected to mechanical chipping during 2002 to remove woody understory growth and to reduce large downed woody debris from the aftermath of Hurricane Hugo in 1989. The remaining four (control) plots were left untreated. The burns were low intensity (mean flame length = 36.2 cm) and slow moving (mean spread rate = 1.18 m min⁻¹). Neither flame length nor rate of spread differed significantly between treatments (ANOVA F's < 0.5, P > 0.7, d.f. = 1,4). Post-burn observations provided somewhat more convincing evidence of treatment effects on fire behavior. According to transect data, only slightly more than half the area in the chip plots burned as compared to upwards of 80% in the burn-only plots. BehavePlus and Hough–Albini (HA) fire models correctly predicted the low intensity, slow moving fires given the observed wind and fuel moisture conditions. Accuracy of BehavePlus predictions depended on the value for fuel height entered in the model. Use of mean fuel height for the fuel depth parameter, as is typically recommended, somewhat overestimated fire hazard in the burn-only plots. However, limiting fuel height to the observed litter depth resulted in roughly accurate predictions. HA predictions for untreated fuels were close to correct even without adjusting fuel depth. When provided with two “high-risk” fuel and fire weather scenarios both models predicted more extreme fire behavior in the untreated fuels. In contrast, chipping appeared to protect against dangerous wildfires as long as fuel heights remained low. Smoke monitoring data from a companion study carried out in the same plots indicated a 60% reduction in smoke particulate production from chipped areas, roughly consistent with predictions of the fire effects model FOFEM. Mechanical chipping is apparently a useful method for limiting fire-hazard and smoke production in long-unburned fuels. However, questions remain concerning the long-term fate of heavy chip fuels and resultant effects on fire and smoke during severe drought.     

The impact of road geometry and surface roughness on fuel consumption of logging trucks

Fuel accounts for more than 35% of transport costs in Swedish forestry, and reduced fuel consumption would provide immediate economic and environmental benefits. The objective of this study was to quantify the effect of road gradient, curvature and surface roughness on fuel consumption of a conventional 60-ton logging truck. The study used a 320-km test track on both public and forest roads. The track was driven with various load weights in both dry summer and wet autumn conditions. Fuel consumption data were retrieved from the truck's CAN-bus system, and road data were measured with a profilograph. Average fuel consumption was 71.4?litres/100?km. A regression analysis showed that the most important factor was the interaction between vehicle weight and gradient, explaining the 86% increase between empty and fully loaded truck. In addition, the regression analysis quantified the individual effects of undulation, curvature and surface roughness, explaining the 107% increase in fuel consumption between the highest and lowest road class. Results from the proposed regression model (R² of 84% for a road section length of 1000?m) were consistent with predictions given by the European ARTEMIS model, and the proposed model can be used to improve cost estimation and route selection.     

Thinning and chipping small-diameter ponderosa pine changes understory plant communities on the Colorado Front Range

Novel fire mitigation treatments that chip harvested biomass on site are increasingly prescribed to reduce the density of small-diameter trees, yet the ecological effects of these treatments are unknown. Our objective was to investigate the impacts of mechanical thinning and whole tree chipping on Pinus ponderosa (ponderosa pine) regeneration and understory plant communities to guide applications of these new fuel disposal methods. We sampled in three treatments: (1) unthinned forests (control), (2) thinned forests with harvested biomass removed (thin-only), and (3) thinned forests with harvested biomass chipped and broadcast on site (thin + chip). Plots were located in a ponderosa pine forest of Colorado and vegetation was sampled three to five growing seasons following treatment. Forest litter depth, augmented with chipped biomass, had a negative relationship with cover of understory plant species. In situ chipping often produces a mosaic of chipped patches tens of meters in size, creating a range of woodchip depths including areas lacking woodchip cover within thinned and chipped forest stands. Thin-only and thin + chip treatments had similar overall abundance and species richness of understory plants at the stand scale, but at smaller spatial scales, areas within thin + chip treatments that were free of woodchip cover had an increased abundance of understory vegetation compared to all other areas sampled. Relative cover of non-native plant species was significantly higher in the thin-only treatments compared to control and thin + chip areas. Thin + chip treated forests also had a significantly different understory plant community composition compared to control or thin-only treatments, including an increased richness of rhizomatous plant species. We suggest that thinning followed by either chipping or removing the harvested biomass could alter understory plant species composition in ponderosa pine forests of Colorado. When considering post-treatment responses, managers should be particularly aware of both the depth and the distribution of chipped biomass that is left in forested landscapes.     

保山市高黎贡山周边社区森林能源现状与供需对策

通过对保山市高黎贡山周边社区森林能源现状调查分析 ,结果表明 :该区现有森林资源 192 3万m3 ,每年的薪材消耗量为 16万m3 ,占总资源量的 0 83%。目前可能提供的薪材量为 7 6万m3 ,仅为需求量的 4 7 5%。作为主要薪材来源的杂灌木林 ,每公顷产柴量只有 4m3 ,仅为一般薪炭林产量的 4 3%。依据该区的经济及资源状况、消费结构、薪材供需和经营现状认为 ,要解决社区薪材供需矛盾 ,需要增加科技投入 ,加大低产林分改造力度 ,提高单位面积产柴量 ,限额开山采樵利用 ,加强经营管理技术     

基于STC89C52的车载油耗实时监测系统设计

针对道路运输企业营运车辆运行过程中燃油消耗状态难以监控的实际情况,本文设计了以单片机STC89C52为核心的车载油耗实时监测系统.提出监控系统的总体设计方案,搭建由电源处理模块、单片机主控模块、油耗数据采集模块、GPS定位模块、GPRS无线通信模块和数据存储模块构成的硬件系统,开发系统控制软件和上位机油耗管理软件.该车载油耗实时监测系统操作方便,成本较低,兼容性强,具有广阔的应用前景.能够对营运车辆行车过程中的实时耗油量进行统计分析,结合生产计划进行燃料供给管理工作,能够有效改善道路运输企业的燃油浪费现象,实现节能增效的目的.     

Analyzing time and fuel consumption in road transport of round wood with an onboard fleet manager

Round wood supply in Austria is often affected by different factors such as bottlenecks or oversupply due to changing market, weather and road conditions. An additional factor impacting the complex wood supply chain is the rising transport costs from the landing to the sawmill. Logging trucks are the primary transportation technology used from the forest to the customer??s site. The objectives of this study were to analyze the actual situation and characteristics of typical trucking activities for round wood supply from the region to an Austrian sawmill. The study used time and fuel consumption, proportion of travel on forest roads and average speed on different functional road classes to estimate productivity and costs. Data collection including GPS-tracking was done using fleet management equipment built into the driver??s cabin. The GPS-routes were analyzed in ArcGIS 9.3 based on the national road network and its attributes. The sawmill studied with a yearly demand of 600,000 m³ round wood was located in southern Austria. In total, more than 2,000 round trips operated by seven logging trucks recorded close to 100,000 km. The transport distance from the forest to the sawmill averaged 51 km. The average share on forest roads within a route to the sawmill was 14.2% with an average speed of 13.5 km/h, whereby the forest road is defined as road with minor importance. Transport costs from the forest site to the sawmill with a truck and trailer were ? 11/m³ solid timber based on an average load size of 25 m³. An average 0.77 l of diesel fuel per kilometer was consumed during a round trip including all work phases. A trip to an interim storage location consumed 2.05 l/km due to the number of work phases without driving distance.     

林木生物质原料收集半径分析——以景谷县生物质发电项目为例

结合景谷县生物质发电项目特点,以翔实的调查数据为依据,以成本的经济性为基点,通过分析原料供求现状、估算原料收集成本,构建原料收集成本与收集半径的关系模型,科学地确定了项目的原料收集半径,以期为项目投资运营的可行性提供科学依据。     

Fuel consumption and exhaust emissions in the process of mechanized timber extraction and transport

The paper focuses on the determination of fuel consumption (CO₂ emission) and exhaust emissions such as CO, HC, NO_x, and PM in the process of timber extraction and transport. A complex assessment of fuel consumption and exhaust emissions was performed for the entire, fully mechanized supply chain including, tree felling, delimbing, and bucking with a harvester, timber extraction with a forwarder and transport with a truck. The performed investigations determined unit exhaust emissions (referred to 1 m³ of timber) for the entire technological process and its individual stages. The investigations of the exhaust emissions and fuel consumption were performed under actual conditions of typical forest operations and transport. State-of-the-art portable emissions measurement system equipment was used for the measurements. The fuel consumption was determined through the carbon balance method. The investigations were performed for the process of extraction and transport of pulpwood. The measurements were performed on location in the town of B?bnik?t near Poznań, in a pinewood forest, typical of this part of Europe. The analysis includes the transport of timber to the lumberyard on a distance of 31.4 km. The total fuel consumption for the entire mechanized supply chain was 2.10 dm³/m³. The total exhaust emissions, however, amounted to: CO—8.91 g/m³, HC—1.19 g/m³, NO_x—45.32 g/m³, PM—4.04 g/m³.     

Market impacts of a multiyear mechanical fuel treatment program in the U.S.

We describe a two-stage model of global log and chip markets that evaluates the spatial and temporal economic effects of government-subsidized fire-related mechanical fuel treatment programs in the U.S. West and South. The first stage is a goal program that allocates subsidies according to fire risk and location priorities, given a budget and a feasible, market-clearing market solution. The second stage is a quadratic welfare maximization spatial equilibrium model of individual State and global product markets, subject to the fuel treatment allocation. Results show that the program enhances timber market welfare in regions where treatments occur and globally but has an overall negative economic impact, once fuel treatment program costs are included. The overall cost of a mechanical fuel treatment program, when considering timber market welfare, transport costs, treatment costs, and timber receipts, exceeds $1000 per acre, implying that the long run fire effects and ecosystem net benefits of a treatment program would need to exceed this figure in order to justify widespread implementation.     

Logistics of supplying biomass from a mountain pine beetle-infested forest to a power plant in British Columbia

Abstract

The search for alternative energy sources has increased the interest in forest biomass. During the past few years, the severe infestation of the mountain pine beetle (MPB) within the forests of interior British Columbia (BC) has led to huge volumes of dead wood that exceed the capacity of the lumber industry. One way to make the most value of the surplus wood is to use it as the feedstock for bioenergy. The high costs associated with harvest and transport, and uncertainty in supply logistics are issues related to forest biomass utilization. This paper presents the development of a forest biomass supply logistics simulation model and its application to a case of supplying MPB-killed biomass from Quesnel timber supply area (one of the most infested areas in the interior BC) to a potential 300 MW power plant adjacent to the city of Quesnel. It provides values of quantity, cost and moisture content of biomass which are important factors in feasibility study of bioenergy projects. In the case of a conventional harvesting system, the biomass recovered from roadside residues in 1 year will meet only about 30% of the annual demand of the power plant with an estimated delivered cost of Can $45 per oven-dry tonne of woodchips. Sensitivity analyses were also performed.     

Pine and spruce stump harvesting productivity and costs using a Pallari KH 160 stump-lifting tool

Abstract

Even though stumpwood may become a significant part of the future fuel mix for combined heat and power plants in Sweden, the harvesting of stumps after regeneration felling is still only performed on a trial basis. Results from time studies on two, 23 tonne, excavators fitted for stump lifting, together with follow-up data on stump lifting and forwarding, are presented. Lifting, splitting, and piling the stumps accounted for 17, 32, and 32%, respectively, of the total productive work time. A predictive model was developed to estimate operational times and productivities when lifting pine and spruce stumps. Stump diameter, species, and terrain conditions contributed significantly to the fit of the model. The model predicts that productivity of stump lifting in spruce sites with easy terrain conditions and average stump diameters of 20 and 40 cm will be 1.23 and 4.19 oven-dry tonnes (ODT) per productive work hour, respectively. This is 43% higher than in pine sites with difficult terrain conditions and the same diameters. In the follow-up data, the productivity in stump lifting varied from 1.5 to 2.9 ODT per productive work hour while the cost for lifting and extraction to roadside varied from 37.8 to 59.4 €/ODT.     

全树削片的研究

本文概要介绍了国内外全树削片的情况。论述了全树木片的生产、应用、存在的问题、解决的办法和我国开展全树削片的前景。指出，我国在３０多年木片生产的基础上，可开展全树削片试验，进而建造全树削片生产基地，利用扶育伐、低产林改造等林木或营造速生纤维林进行全树削片。它将成为林业企业新的经济增长点。是发展、振兴森林工业，使森工企业走出低谷的一项重要措施。     

Behind the flaming zone: Predicting woody fuel consumption in eucalypt forest fires in southern Australia

Pre-fire woody fuel (diameter > 0.6 cm) structure and its consumption by fire were measured at experimental/prescribed fires and high intensity wildfires in eucalypt forests in southern Australia in order to better understand and model the dynamics of woody fuel consumption. Two approaches were used in model development: (1) a fire or plot level analysis, based on a dataset which includes the proportion of the pre-fire woody fuel load consumed at each fire; and (2) a stage level analysis, based on a dataset where woody fuel consumption was measured at a woody fuel particle level (i.e. pre-fire and post-fire diameter). For the plot level analysis a generalised linear model (GLM) approach identified the Forest Fire Danger Index (FFDI) as the best predictor of the proportion of woody fuel consumed, with an R² of 0.58 and mean absolute error of 10%. The stage level analysis recognised the various combustion stages through which a burning woody particle would pass, but failed to develop an accurate model that predicted the ignition, partial and full consumption of woody fuels based on fuel, fire behaviour and environmental variables. Analysis showed that consumption of woody fuel particles is highly variable and that variation in fire behaviour potentially has a greater impact on woody fuel consumption, than does variation in fuel characteristics (e.g. state of decay, fuel suspension and interactions with other fuel particles). The FFDI GLM provides forest and fire managers with a tool to manage woody fuel consumption objectives and may assist fire managers with forecasting post-frontal fire behaviour. The FFDI GLM may also assist forest and fire managers to better meet land management goals and to comply with air quality and emission targets.