发电厂森林残留物的三级采购--加拿大Assignment代写范文

加拿大Assignment代写范文:“发电厂森林残留物的三级采购”，这篇论文主要描述的是Electrabel公司是一件比利时的电力生产商，该公司在研究以木材作为燃料的发电系统，在这个火力发电的过程当中需要考虑来自经济和环境等方面的制约因素，我们需要对发电所产生的森林残留资源进行统计，分析产量以及采购运营的成本。

Abstract

This paper presents the methods used to establish a wood-fuel supply chain for coal-/red power plants taking into account wood resources, potential suppliers and /nancial, economic and environmental constraints. The /rst step is a quantitative and qualitative evaluation of forest residues around the power plants. At the next stage, the supply chain characteristics are analyzed. Finally, a combination of forest residue sources and supply chains is selected under the constraints of the multiple criteria of the energy producers. In the present case study, the conclusion of the analysis is that an optimal strategy includes three levels: one base level made up of large-scale loggers harvesting softwood from /nal cuts, one top level made up of medium-scale loggers mainly harvesting hardwoods, and a reserve level made up of small-scale loggers and farmers. Detailed characteristics of these levels are given. ? 2003 Elsevier Science Ltd. All rights reserved. Keywords: Forest residues; Bioenergy; Harvesting; Supply; Strategy; Biomass; Co/ring 1. Introduction The commitments entered into within the framework of the Kyoto Protocol signed by Belgium and its European partners in April 1998, result for Belgium a reduction of 7.5% of emissions of all greenhouse gases compared to the level of 1990 [1]. In the Walloon Region, renewable energy should cover 10% of the total electricity consumption by 2010, with biomass representing 65% of that. However, available resource with no or little demand for, we notice that forest residues represent more than 70% of the potential of dry biomass, equivalent of 7.6 Petajoules per year [2,3]. Forest residues therefore represent a considerable step towards reaching the /xed objectives.This paper is based on a case study carried out for ELECTRABEL, the main Belgian power producer. In order to comply with the new regulations regarding “green” electricity, they were looking to supply two of their old coal-/red power plants with 10% wood coming directly from the forest. The two coal-/red power plants are located in Wallonia (Southern Belgium) along the Meuse. This paper presents the methods used to establish a forest fuel supply chain for coal-/red power plants taking into account wood resources, potential suppliers and /nancial, economic and environmental constraints or wishes.

2. Material and method 材料和方法

This section includes the methodology used to assess the forest residue resource, to characterize the 0961-9534/03/$ -see front matter ? 2003 Elsevier Science Ltd. All rights reserved. PII: S0961-9534(02)00161-7 

402 J.-F. Van Belle et al./Biomass and Bioenergy24 (2003) 401–409 supply chains and to select an optimal supply strategy for the power plants. DiKerent studies have already been carried out in order to calculate delivery costs for wood fuel taking into account multiple parameters. Asikainen et al. [4,5] showed that an important cost factor in wood fuel procurement is the scale of operation. Harvesting machinery is expensive and thus the annual output considerably aKects the costs. In addition, the greater the share of the potential fuel supply recovered, the higher the cost of procurement. The eKect of plant localization was also studied by Graham et al. [6,7]. This study takes into account these factors but tries also to integrate other factors usually not included like social considerations. 

2.1. Evaluation of forest residue sources

In the short term, the supply of forest residues is not constant but Muctuates with the extent of harvesting activities. Annual harvested volume is depending on the forest resource, forest management types, climatic hazards, forest industry characteristics, economic conditions, etc. To estimate quantitatively and geographically forest residue resources in Wallonia, data from the Walloon Permanent Forest Inventory were analyzed [8]. This inventory is based on a grid of permanent plots of about 0:1 ha measured every 10 years. The distance between plots is 1000 m east–west, 500 m north–south, so that each plot represents 50 ha. At the time of the study, only 30% of the inventory had been completed, each plot thus representing 166:67 ha (sc in Eq. (1)). The principal data collected on each plot were: topography, soil and vegetation type, tree circumference at 1:5 m, heights, stand age, structure. All these data were treated to separate the stands into diKerent categories and to calculate the standing volume of commercial wood. In relation to the total wood volume, it is necessary to estimate the volume harvested annually as well as the harvesting method. Logging contractors, forest owners and lumber companies were surveyed to determine the amount harvested, species, forest operations, logging equipment, minimum diameter, etc. This was done in collaboration with the National Federation of Loggers (FEDEMAR) which represents 80% of the volume harvested annually in Belgium. The questionnaire was /lled in by 65% of its members. These /gures were related to the previous estimations and to studies of within-tree biomass components for diKerent species [9–12]. This permits the calculation of forest residue amounts as a percentage of commercial wood harvested, species, type of stands and type of harvesting (frij in Eq. (1)). Eq. (1) gives the amount of forest residues produced yearly by type of stands and type of harvesting:

where Rij is the amount of forest residues produced yearly (dry ton=year), i is type of forest, j is type of harvesting operation, k is trees in a sample plot, l is sample plot, h is individual tree height, d is individual tree diameter, sp is Species, s is sample plot area (ha), wd is speci/c density of wood (dry tons=m3), sc is scaling factor for sample plot (ha), fr is forest residue factor (%). Finally, the results were integrated into a geographic information system to calculate the transport distance to the power plant location. Distances between each forest plots from the grid and the power plant were calculated as the crow Mies and multiplied by a factor of 1.3 taking into account the shape of the network.

2.2. Characterizing supplychains

The many harvesting systems for forest residues most suitable to Belgian conditions (forests, loggers, etc.) were selected for a detailed economic analysis. Hourly cost of equipment was calculated according to Tissot [13] as elaborated in Eqs. (2)–(4) below. The supply cost of system i is

sci =fci +hci +tci +sti; (2)

where the harvesting cost,

hc = [ic(al.1 +ir=100+is=100)+mt +fo + ml ur.1]mc pd.1 (3)

and the transportation cost, tc = [ic(al.1 +ir=100+is=100)+mt +fo + ml ur.1]mc ad as.1cv.1dd: (4)  

J.-F. Van Belle et al. / Biomass and Bioenergy24 (2003) 401–409 403

From the systems available at the time of the study [14–19], seven were selected for more thorough analysis. The selection was done according to the following criteria: . degree of maturity: the technique had to be reliable and well established in other countries, . covering of a wide range of investment costs and yearly productivities in order to /nd supply chains that ful/l the diKerent investment and production capacities of potential suppliers, . good level of acceptability amongst loggers, con/rmed through meetings held with them.

2.3. Selection of residue sources and supplychains

The choice of forest residue supply chains for energy must include more than the /nal cost of fuel delivered at plant, primarily because the resource and the way it can be harvested and processed is very variable. This may have drastic inMuences on the power plant investment and operating costs as well as on the amount of fuel required. The fuel quality required was wood chips of 2–5 cm average length with a maximum of 10 cm. No special requirements for moisture content were speci/ed since it was assumed that the excess heat of the power plant could be used for drying wood fuel. The elements to be considered were the following: Fuel availability: There must be enough forest residues to harvest yearly to provide the 30,000 dry tons of fuel required. Supplyregularity: Although the harvesting of forest residues is an entirely new activity, the electricity producer needs to co-operate with stable and reliable companies.

404 J.-F. Van Belle et al./Biomass and Bioenergy24 (2003) 401–409 Fuel quality: Especially the particle size distribution. Silos, transporting chains and furnace feeders are very sensitive to size of wood chips. Chips which are too large can create “bird nests” or block the feeders. Chips which are too small (/nes) can produce bridges in silos and accelerate self ignition. Price: the objective is to get the fuel at as competitive price as possible. Social, environmental and economic e7ects in the region: The main objective of using wood fuel in the power plant was to comply with renewable energy targets but also to improve the positive public image of the power producer. We had to pay attention to concerns like competition with traditional activities (pulpwood), development of local employment, environmental constraints and fears about sustainability, traQc, etc. Thus a system with high positive eKects may be chosen even if it does not produce fuel at the cheapest price. The two last points may seem counter each other. In order to obtain a competitive price and guarantee the delivery, investing in a capital-intensive supply chain with only a small number of companies could be considered. Nevertheless, the drawback may be the diQculty of /nding partners.

3. Results 结果

3.1. Available forest residue sources

The total amount of forest residues

produced yearly in Wallonia was estimated at around Table 1 400 000 dry tons per year coming especially from the eastern part of the country (provinces of LiRege and Luxembourg). Residues from hardwood trees account for 160 000 dry tons per year and from softwood trees 240 000 dry tons per year with 94 000 tons coming from clearcuts. Fig. 1 shows the variability of forest residue sources and quantities in relation to the distance from a power plant (in this case the power plant located at les Awhirs near LiRege). Since power plants are generally located in urban areas, there are very few forest residues within 25 km. In this case, the main source is located at a distance of 40–70km from the plant.

3.2. Supplychain characteristics

The system includes equipment ranging from a small disc chipper mounted on a 75 hp farm tractor up to a truck-mounted tub grinder. Crane-fed drum chippers mounted on forwarders are also included. The investment cost ranges from 45:860 for the least capital-intensive system to 545 366 for the more expensive (Table 2). Yields range from 0:6 dry tons=pmh for the less productive system to 10:4 dry tons=pmh for the more eQcient one. This, in turn, gives a potential yearly production of from 720 to 12 780 dry tons. The most expensive system, working at full cost (and not marginal costs, as it could be with farmers for instance), producesatacostof105 =dry ton

(Table 3). The most eQcient system creates a cost of only 31 =dry ton. Amount of forest residue (tons of dry matter) produced annually by region, species and type of forest operation Broadleaved trees Softwood trees Total Clearcut Thinnings First thinning Total Province Private Public Total Private Public Private Public Private Public LiRege Luxembourg Namur Hainaut Brabant 11 938 27 561 26 956 11 607 1870 12 003 27 713 27 104 11 671 1881 23 941 55 273 54 060 23 279 3751 19 941 33 327 8759 1157 441 9930 16 595 4361 576 219 19 941 33 327 8759 1157 441 19 859 33 190 8723 1152 439 4218 7050 1853 245 93 2109 3525 926 122 47 75 998 127 014 33 381 4409 1680 99 939 182 287 87 441 27 688 5431 Total 79 932 80 372 160 304 63 623 31 681 63 623 63 363 13 459 6729 242 478 402 782 

J.-F. Van Belle et al./Biomass and Bioenergy24 (2003) 401–409 405 0 10.000 20.000 30.000 40.000 50.000 60.000 70.000 Amount of residues (odt) 0 50 100 150 Distance (km) Fig. 1. Amount of residues versus distance. Table 2 Harvesting processes for forest residues – characteristics S1S2 S3 S4 S5 S6S7 Equipment 75 WP 120 WP tractor 150 WP tractor Forwarder Forwarder Tub grinder 150 WP tractor agricultural Disc big disc equipped with equipped with 1 simple big disc tractor with chipper chipper tipper a big chipper a big chipper forwarder chipper tipper disc chipper agricultural trailer small trailer simple forwarder trailer small trailer 70 WP tractor for transport 70 WP tractor tipper trailer tipper trailer Type of chipper Disc chipper Disc chipper Drum chipper Drum chipper Drum chipper Hammer or Disc chipper teeth chipper Type of ground Regular Regular Regular Regular Regular Stringy Regular material 5–50 mm 5–50 mm 10–75 mm 10–75 mm 10–75 mm 10–100 mm 5–50 mm Type of residues Thinnings of Thinnings of Thinnings and Clearcut of Clearcut of Clearcut of Full trees in hardwood hardwood clearcut of hardwood and softwood softwood /rst softwood trees trees hardwood and softwood trees trees trees thinning softwood trees roadside StaK(man) 2 1 2 2 2 × 234 Investment ( ) 45 860 85 520 146 250 371 840 545 370 520 580 146 260 Availability 1200 1200 1200 2000 2000 1200 1200 (h/year) In relation to transport, the same criteria were used as for harvesting systems. Two systems were selected and analyzed (Table 4): a truck with two containers of 35 m3 each and a semi-trailer able to store 70 m3 in its bin. The annual amount transported by these systems ranges from 6750 dry tons for the truck with containers transporting softwood chips to 11 200 dry tons for the semi-trailer with hardwood chips. In Fig. 2, the relationship between the transport cost ( =dry ton) and the amount to be harvested yearly can be seen as well as the spatial intensity of recovery. The higher the quantity needed, the higher the transport cost. The same consequences appear when the recovery rate is lower. The transport cost was found to vary between less than 2:5 =odt up to 19:8 =odt. 

406 J.-F. Van Belle et al./Biomass and Bioenergy24 (2003) 401–409 Table 3 Harvesting processes for forest residues—productivity and costs S1 S2 S3 S4 S5 S6 S7 Cost ( =h) 63.1 63.9 111.2 149.2 198.7 292.5 157.6 Yield (odt/h) Average 0.8 1.2 2.4 3 4 8 2.8 Min 0.6 0.8 1.7 2.1 3.5 5.6 2 Max 1 1.6 3.1 3.9 5.25 10.4 3.6 Yield (odt/year) Average 960 1440 2880 6000 8000 9600 3360 Min 720 960 2040 4200 7000 6720 2400 Max 1200 1920 3720 7800 10 500 12 480 4320 Cost ( =odt) Average 78.9 53.3 46.4 49.7 49.7 40.7 56.3 Min 63.1 40.0 35.9 38.3 37.9 31.3 43.8 Max 105.2 80.0 65.4 71.0 56.8 58.2 78.8 Table 4 Transport system characteristics and costs System Truck and containers Truck and semi-trailer Volume per container Annual turnover 2 × 35 m3 78 000 70 m3 95 440 Annual amount transported 6750 odt softwood 9000 odt hardwood 8400 odt softwood 11 200 odt hardwood Transport cost for softwood Transport cost for hardwood 0:32 0:23 =odt=km return =odt=km return 0:2 =odt=km return 0:15 =odt=km return DiKerent storage options were also analyzed, from open air to roof covered and air fan. The costs depend on storage type and duration of storing. Calculations were made for 3, 6, 9 and 12 months. The costs range from 0:32 =m3 for a 3 month storage in an open air pile to 1:7 =m3 for a 12 month storage in a covered building with air fan.

3.3. Residue sources and supplychain selection

Taking into account the forest residues, supply chain and logger characteristics, a strategy was established for supplying 30 000 tons=year (Table 5). It is made of 3 tiers. The /rst one referred to as ‘hard core’ provides the main part of the supply, i.e. 60–70% at a competitive price. This tier would be made up of 3 or 4 large-scale loggers, usually working in softwood clearcuts and harvesting over 60 000 m3 of roundwood yearly. The forest residue harvesting system which suits their conditions best would be a crane-fed drum chipper mounted on a forwarder. Each one would harvest about 6000 dry tons per year, for a total of between 18 000 and 24 000 dry tons per year for the whole tier. Harvesting costs represent about 50 =odt. Transport would be done by truck and semi-trailer, the total cost at mill gate being around 60 =odt, i.e. 3:12 =GJ. If storage, buying price and risk are taken into account, the cost would be increased to 78:7 =odt or 4:12 =GJ. The second tier is made up of smaller-scale loggers who are not be able to invest large amounts or to organize large-scale harvesting. These loggers are usually occupied in hardwood harvesting. This ‘top level’ tier would be made up of 1–3 crews using a crane-fed drum chipper mounted on a tractor. Depending on varying assumptions for raw material cost, the storage costs and risk, the /nal millgate price ranges from 58 to 84:7 =odt, i.e. from 3 to 4:36 =GJ. 

J.-F. Van Belle et al./Biomass and Bioenergy24 (2003) 401–409 407 Transport cost [ /odt] 20 15 10 5 0 0 50.000 100.000 150.000 200.000 250.000 300.000 350.000 400.000 Amount of forest residues [odt] 100 % 75 % 50 % 25 % Recovery rate Fig. 2. Transport cost versus yearly amount and recovery rates. Table 5 Characteristics of the diKerent levels of supply Levels/layer 1 2 3 Hard core Soft core Peak Loggers type Large Medium Small Number 3–4 1–3 10–30 Roundwood logged per year . 60 000 m3 10 000–60 000 m3 . 10 000 m3 Types of logging residues harvested Softwood in clearcut Hardwood in /nal Hardwood in thinning cut or thinning Potential forest residue selling price ( =odt) 0–11.2 0–19.3 0–19.3 Harvesting equipment S4 (S5) S3 S1 (S2) Investment ( ) 371 840 146 260 45 860 Harvesting cost ( =odt) += . 50 += . 46:4 78.9 Amount harvested/logger (odt/year) += . 6000 += . 2880 100–1000 Total amount harvested (odt/year) 18 000–24 000 3000–9000 1000–10 000 Type Semi-trailer Container Container Transport cost ( =odt) 9.9 11.6 11.6 Storage Not necessary Not necessary or Concrete or roadside container Storage cost to reach 30% mc ( =odt) 2.1 1.6 1.6 Average total procurement cost ( =odt) 59.5 58 90.5 Cost per GJof dry matter ( =GJ) 3.1 3 4.7 Total cost with storage, buying 78.7 84.7 120.5 price and risk (10%) ( =odt) Cost by GJof dry matter ( =GJ) 4.1 4.4 6.2

408 J.-F. Van Belle et al./Biomass and Bioenergy24 (2003) 401–409 Finally, a “reserve level” tier would be made up of small-scale loggers or farmers working in thinnings, totally harvesting less than 10 000 m3=year. This group of 10–30 companies would have an individual investment of maximum 45 860 if a tractor is included but normally would use it at marginal cost with a small disc chipper. The production of wood chips would be a marginal by-product. They would harvest between 100 and 1000 dry ton per year on a marginal basis. If the total cost is taken into account, the /nal price would range between 90.5 and 120:5 =odt. Through local storage, this tier would act as a buKer, for rapid supply if one crew failed temporarily in the upper tiers. It would also satisfy externality requirements by providing extra revenues for small-scale loggers and farmers.

4. Conclusions and discussion 总结和讨论

The most economically eQcient option as found by calculation is not always the best alternative. By taking into account other parameters found signi/cant by actors of the bioenergy chain but not directly measurable, the optimal option may appear diKerent and may not be as straightforward than usually found by calculation. In this case study, even if the S3 harvesting system was found the most viable, it was not elected by the majority of the loggers who preferred a more robust system with equipment closer to what they were used to. Social and safety considerations promoted also a third option. Before choosing a strategy for supplying a power plant with a source of biomass (in this case, forest residues), it is crucial before and after economic calculations to interact with the future partners of this procurement chain.

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