UBC Alex Fraser Research Forest 2009 UBC Alex Fraser Research Forest Welcome to our Classroom Productivity and Cost of Producing Forest-Origin Feedstocks for Biofuels: Seven Case Studies Near Williams Lake BC By: Don Skea, RFT and Ken Day, MF, RPF Introduction Production and delivery of feedstock from forestry operations to biofuel plants is a rapidly developing activity in British Columbia. Consumption of wood residues by the bio-energy industry has increased significantly in the past year. At the same time the collapse of the U.S. housing market and subsequent world-wide recession has resulted in production curtailments from the primary wood processors in BC. As a result there are numerous operations securing fibre-supply from a variety of fuel sources throughout the province. Non-hydroelectric renewable energy accounts for about 18% of the provincial energy budget, and the majority of that energy is derived from combustible renewable waste (Evans 2008) -- a contribution that is nearly equal to hydro- electricity. The majority of that contribution comes from the existing pulp industry, with an expanding biomass electrical generation capacity. In Williams Lake, BC there are five major sawmills, a plywood plant, and several wood-based manufacturing industries, all of which generate a significant supply of combustible renewable waste. Two bio-energy enterprises have arisen to eliminate beehive burners and make use of the waste stream from the wood-products manufacturers: EPCOR Power L.P. Pinnacle Pellet Inc. Production curtailments and temporary or indefinite closures have affected all of the manufacturers, and therefore put significant pressure on the bio-energy producers to source raw material from the forest for their processes. This project has tracked 7 case studies in order to understand: Production rates and costs of forest-derived feedstock Operating methods to improve cost efficiency Measurement protocols and conversion rates from raw debris through to delivered feedstock Quality implications to the consumer. • • • • • • Contents Introduction 1 Case Study Descriptions 2 Methods 4 Case Study Data Collection 4 Case Study Implementation 5 Results 6 Discussion 8 Feedstock Quality 8 Significant Lessons Learned 10 Outstanding Issues 13 Recommendations 13 Conclusions 14 References 14 Appendix 1 -- Case Study Reports 15 72 South Seventh Ave. Williams Lake, BC. V2G 4N5 Ph (250)392-2207 Fax (250)398-5708 http://www.forestry.ubc.ca/resfor/afrf/index.htm Acknowledgements: We gratefully acknowledge funding for this work from FPInnovations (FERIC Division) through the Woody Debris Management Program of the Province of B.C. We appreciate the collaboration and support of Wade Watson, RPF and Wayne Clarke, P.Eng. of EPCOR Williams Lake; Craig Lodge, RPF and Harold Berkholtz of Pinnacle Pellet Ltd.; and Brian Hansen and Phil Therriault, RPF of Pioneer Logging. Finally, we are grateful for the collaboration of Dr. Shahab Sokhansanj and Dr. Igathinathane Cannayen of UBC Chemical Engineering, Dr. Kevin Lyons of UBC Forestry, and Jack MacDonald, RPF of FPInnovations. April 30, 2009
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� UBC Alex Fraser Research Forest 2009
UBC Alex Fraser Research ForestWelcome to our Classroom
Productivity and Cost of Producing Forest-Origin Feedstocks for Biofuels: Seven Case Studies Near Williams Lake BCBy: Don Skea, RFT and Ken Day, MF, RPF
Introduction
Production and delivery of feedstock from forestry operations to biofuel plants is a rapidly developing activity in British Columbia. Consumption of wood residues by the bio-energy industry has increased significantly in the past year. At the same time the collapse of the U.S. housing market and subsequent world-wide recession has resulted in production curtailments from the primary wood processors in BC. As a result there are numerous operations securing fibre-supply from a variety of fuel sources throughout the province.Non-hydroelectric renewable energy accounts for about 18% of the provincial energy budget, and the majority of that energy is derived from combustible renewable waste (Evans 2008) -- a contribution that is nearly equal to hydro-electricity. The majority of that contribution comes from the existing pulp industry, with an expanding biomass electrical generation capacity.In Williams Lake, BC there are five major sawmills, a plywood plant, and several wood-based manufacturing industries, all of which generate a significant supply of combustible renewable waste. Two bio-energy enterprises have arisen to eliminate beehive burners and make use of the waste stream from the wood-products manufacturers:
EPCOR Power L.P.Pinnacle Pellet Inc.
Production curtailments and temporary or indefinite closures have affected all of the manufacturers, and therefore put significant pressure on the bio-energy producers to source raw material from the forest for their processes.This project has tracked 7 case studies in order to understand:
Production rates and costs of forest-derived feedstockOperating methods to improve cost efficiencyMeasurement protocols and conversion rates from raw debris through to delivered feedstockQuality implications to the consumer.
72 South Seventh Ave. Williams Lake, BC. V2G 4N5 Ph (250)392-2207 Fax (250)398-5708 http://www.forestry.ubc.ca/resfor/afrf/index.htm
Acknowledgements:We gratefully acknowledge funding for this work from FPInnovations (FERIC Division) through the Woody Debris Management Program of the Province of B.C. We appreciate the collaboration and support of Wade Watson, RPF and Wayne Clarke, P.Eng. of EPCOR Williams Lake; Craig Lodge, RPF and Harold Berkholtz of Pinnacle Pellet Ltd.; and Brian Hansen and Phil Therriault, RPF of Pioneer Logging. Finally, we are grateful for the collaboration of Dr. Shahab Sokhansanj and Dr. Igathinathane Cannayen of UBC Chemical Engineering, Dr. Kevin Lyons of UBC Forestry, and Jack MacDonald, RPF of FPInnovations.
April 30, 2009
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Case.Study.Descriptions
1. Grassland restoration project, Knife Creek Block, Alex Fraser Research Forest Block 224 Whole tree logging removed green non-merchantable trees and parts of trees (primarily green Douglas-fir) from 2.7 ha (net area harvested) to a round pile on a landing in anticipation of burning.
2. Tolko Cutting Permit 757 Block WlK067 Clearcut harvest of 16.2 ha of mountain pine bark beetle-affected lodgepole pine by feller buncher and grapple skidder to roadside processing, with post-harvest processing debris piled at roadside in anticipation of burning.
3.(a, b) Williams Lake Municipal Airport fuel reduction treatment Removal of dead lodgepole pine and understory Douglas-fir, leaving a residual stand of primarily Douglas-fir. Whole-tree material was piled at the landing by a forwarder in anticipation of comminution, with dry pine sorted from green Douglas-fir. Comminution was completed in two different operations at different times with different grinders, and so this project has been treated as two separate case studies.
4. Fox Mountain Road fuel reduction treatment. Removal of understory Douglas-fir fuel ladders on 6.2 ha in the IDFdk3, with hand falling and forwarding to roadside by quad with skidding arch or Ford New Holland™ tractor with Farmi™ winch. Comminution on public roadside.
5. 150 Mile Fire Hall fuel reduction treatment. Removal of understory Douglas-fir fuel ladders and dead lodgepole pine from an uneven-aged Douglas-fir stand on 1.4 ha in the IDFdk3. Hand falling with Cat 518™ line skidder to paved parking area.
6. Wildwood Fire Hall fuel treatment. Removal of dead lodgepole pine and thinning of residual lodgepole pine to avoid wind and snow damage, on 1.0 ha in the IDFdk3. Hand falling with Cat 518™ line skidder to landing, sorting dead pine from green pine before comminution.
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Figure 1: Location map of the vicinity of Williams Lake showing seven case study locations where bio-en-ergy feedstock was produced.
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The case studies covered a wide range of equipment employed and project scale. Table 1 summarizes the seven case studies reported in this project.
Table 1: Location and description of seven case studies reported from the vicinity of Williams Lake, BC.
Case Study Description Grinding machine type Truck Type Loads
(count)
Cycle Time (hrs)
1 Alex Fraser Research Forest, Knife Creek Cutblock 224
Vermeer 6000TX horizontal grinder, includes a JD200 LX excavator w/thumb to feed grinder
and load trucks
53 ft high-boy chip van 5 2.6
2Borland Creek, Tolko
Industries Ltd. CP 757 Blk WlK067
Peterson 4710B horizontal grinder, includes two butt-n-top loaders to feed grinder
53 ft high-boy chip van 27 2.9
3a Williams Lake Municipal Airport
Vermeer 6000TX horizontal grinder, includes a JD200 LX excavator w/thumb to feed grinder
and load trucks
53 ft high-boy chip van 13 1.9
3b Williams Lake Municipal Airport
DuraTech 9564 horizontal grinder, includes 1 butt’n’top loader to feed grinder
53 ft high-boy chip van 35 1.5
4 Fox Mtn Fuel Treatment Area
Custom built Beast Bandit 2680 on tri-axle high-way tractor with picker unit
53 ft chip van and
Roll-off bins19 2.6
5 150 Mile Fire Hall Custom built Beast Bandit 2680 on tri-axle high-way tractor with picker unit Roll-off bins 3 3.0
6 Wildwood Fire Hall Custom built Beast Bandit 2680 on tri-axle high-way tractor with picker unit Roll-off bins 4 1.5
Methods
Case.Study.Data.Collection
Harvest information was collected from scale returns, cruise data, site plans and on-site observations.A harvest area that contributed to the piles of debris included in the case study was defined by GPS traverse. The bulk volume of each debris pile was assessed by: - determining the area of the base of the pile by GPS traverse, supplemented with lengths and widths where required - measuring or estimating the height to the peak height (highest point) and to “box height” (as if the pile was compressed into a box with straight sides) - assigning a geometric shape that best describes the form of the pile, either cube, wedge or pyramid - post-processing in a “debris pile calculator” spreadsheetpost-processing in a “debris pile calculator” spreadsheet A qualitative assessment of each pile considering -species content by percentage - product category (i.e. pellet feedstock – dry, no needles; hog chip – green, contains needles and bark; or other – potential for pulp chip. ) - categorizing the pile density as loose – rough piled usually fresh, compact – cured pile sitting for a period of time or
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tight-compressed, also log form - alignment of the pile as either poor (random) or good (same direction) - volume distribution in the pile by percentage of tops, long butts (short logs) or finesComminution was completed by one of several different contractors engaged by the Research Forest or Pioneer Logging to provide feedstock for EPCOR Williams Lake Power Plant or Pinnacle Pellet Williams Lake.The volume of comminuted debris (chips) was calculated by: - determining the area of the base of the pile by GPS traverse - measuring the height to the peak height (highest point) - assigning a geometric shape that best describes the form of the pile as a cone or trapezoid - post-processing in a “chip pile calculator” spreadsheetRatios of biomass removed to area of origin were calculated. - Bulk pile volume was compared to harvest area (m3/ha) - Green Metric tonnes of chips was compared to harvest area (tonnes/ha) and harvest volume (tonnes/m3).Mobilization and de-mobilization time and costs were tracked from time slips and low-bed invoices.Machine charge rates were based upon rate quotes given to the authors by the contractors, and do not necessarily represent actual cost experience.Shift-level productivity of the grinding and loading operations were tracked by productive machine hours from the time card and engine clock.Net green weight of each truck load was measured by weigh scale at the receiving plant.Oven dried weight was estimated by sampling green debris at the loading face, at a frequency of one sample per truckload. Samples were sent to FPInnovations - FERIC or to Researchers at UBC Chemical Engineering for drying to oven-dry condition. Moisture content was calculated by the wet basis according to the following equation: MC%=(Ww-Wd)/Ww where Ww is wet weight and Wd is dry weightStandard measures were adopted GMt is Green Metric tonnes, and ODt is Oven Dried tonnes (ODt = (1-MC) x GMt)
Case.Study.Implementation
Each case study was implemented in concert with operational projects, which provided realistic context and logistical challenges for the project. During the course of this project forest-origin feedstocks for bio-energy graduated from an interesting question to an urgent necessity for Pinnacle Pellet and EPCOR in Williams Lake. This shift was due to a series of curtailments and shutdowns in the local sawmill industry, drying up the supply of sawmill waste that was the principle feedstock for the two bio-fuel consumers. Very soon all of the grinding and trucking contractors available locally were fully booked to provide feedstock to the local plants, an activity that was co-ordinated locally by Pioneer Logging. Case studies 1 and 2 focused on roadside or landing debris that had been piled for burning after processing a commercial sawlog harvest. Materials were not stacked or sorted with grinding in mind. Case study 1 was a grassland restoration treatment described by Koot (2008). Case study 2 was an operational clearcut harvest in the Spokin Lake area at 15 km on the 2300 Road, and became part of a much larger grinding operation conducted by Pioneer Logging.
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The remaining case studies were implemented to remove fuels from interface fuel reduction treatments in the area of Williams Lake, and detailed reports on the stand treatments are available (Day et al. 2009, Day and Rau 2009). These fuel reduction treatments gathered the dead pine and understory fuel ladders, delivering them to roadside or landing for disposal by grinding. Materials were stacked with grinding in mind, and sorted to provide dry pine to Pinnacle Pellet and green Douglas-fir and green lodgepole pine to EPCOR. Effective December 1, 2008 the Province of B.C. made changes to the Interior Appraisal Manual that created an administrative process for consuming forest-origin feedstocks. Post-harvest debris and other whole-tree material became subject to scaling and tenure provisions to comply with that change (Sapinsky and Groves 2008). Therefore each case study completed after December 1 required a tenure arrangement and scaling provisions which delayed implementation. In practise, the changes meant that each case study needed a ‘Forestry Licence to Cut’ issued by the Central Cariboo Forest District, and scaling procedures acceptable to the District Scaler. Stumpage is also payable according to the standard operating procedures generated by Sapinsky and Groves (2008). In each case study the authors:
measured piles after logging; arranged for the comminution and delivery in cooperation with individual contractors or through Pioneer Logging;supervised the grinding and trucking phases; measured piles of chips to determine chip volume before trucking;gathered and shipped 38 litre samples of ground material for feedstock characterization studies by UBC Chemical Engineering (Case studies 1, 2, and 3 only); - samples were gathered systematically from waist height on each chip pile at a ratio of one sample per expected truckload - bins were closed securely and labelled, and shipped to Vancouver by freight truck - samples were stored in their bins in a cold room at near 0°C until they were processed - bulk density of the material was measured by filling a vessel with a sample, tapping the vessel 50 times on a hard surface, measuring the resulting volume of the sample and the green mass of the sample - processing for moisture content was conducted according to standard ASABE S358.2 (American Society of Agricultural and Biological Engineers), which involves drying samples in a convection oven at 105°C for 24 hoursgathered time cards and load description slips from contractors, and obtained load slips from the receiving scale. The receiving scale provided moisture content samples for loads received, and UBC Chemical Engineering provided moisture contents from each sample shipped after grinding.
Results
The results of each case study are described in detail in the Appendices. The scale of each project and equipment type used varied significantly between case studies, resulting in a wide range of cost experiences (Table 2). Because these are all quite different cases, it is not appropriate to seek average costs and productivities across cases, and so none are reported. Moisture content was quite variable, with individual samples ranging from a low of 23% to a high of 47% (Figure 2). Average moisture contents and bulk density seem to vary considerably between case studies (Table 3).
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Table 2: Results of grinding and trucking case studies conducted from October 2008 to March 2009.
6 260± 25 17 17 30 est $93.75 n/a $9.82 $147.95* Moisture content values for case study 1-3a are provided by Dr. Shahab Sokhansanj and Dr. Igathinathane Cannayen of UBC Chemical Engineering, from samples taken from each pile after grinding. Values for case study 3b are in preparation at the time of reporting. Moisture content values for case study 4-6 are estimates based upon scale samples only.
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Figure 2: Moisture content of samples reported by Dr. Shahab Sokhansanj of UBC Chemical Engineering from samples gathered from three case studies. Measurments taken according to standard ASABE S358.2, 2003 (American Society of Agricultural and Biological Engineers).
Table 3: Moisture content and bulk density of samples reported by Dr. Shahab Sokhansanj of UBC Chemi-cal Engineering from samples gathered from three case studies. Measurments taken according to standard ASABE S358.2, 2003 (American Society of Agricultural and Biological Engineers).
Case Study Date Range Number of Samples
Moisture Content (% Wet Basis)
Bulk Density (kg/m3)Collection Drying
Mean Std. Dev. Mean Std. Dev.
1 Oct 28-29/08 Nov. 4/08 5 31.5 4.5 206 312 Mar 10-11/09 Mar 12/09 20 30.2 4.1 174 13
3(a) Jan 15-16/09 Jan 23/09 13 39.1 7.4 212 21
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Discussion
Seven different case studies are reported, ranging from 20 to 896 GMt green mass. The small case studies (4, 5, 6) were treated with a truck mounted self-feeding grinder, with chips deposited directly into roll-off bins, while the larger case studies (1, 2, 3a, 3b) were treated with large horizontal drum grinders fed by a log loader. As one might expect, cost is inversely proportional to project size, because of the efficiency associated with larger projects. When individual case studies are ranked by their total product cost ($/ODt) we find generally decreasing unit costs as a function of increasing green mass (Figure 3). In other words, larger projects cost less per Oven Dry tonne. This is due in large part to the selection of the grinder, and the inefficiency of mobilizing a project for a small volume of debris.The manner of organization on the landing is also likely a significant contributor to the cost of the project. Our lowest-cost experience was found in case-study 3a and 3b, where debris was stacked at the landing with grinding in mind. Landing piles were well organized and readily accessible to the grinder, which minimized the amount of handling to feed the grinder, and maximized grinder throughput. Case study 1 and 2, by comparison, were focused on landing piles that had been stacked for burning, and material needed to be organized before feeding into the grinder. This increased the cost of feeding the grinder and reduced grinder efficiency.
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Figure 3: Seven feedstock case studies ranked by product cost from lowest to greatest show that product cost ($/ODt) is generally inversely related to the green mass of chips produced in a given case study; there are, however, significant departures from that trend. Phase costs ($/GMt) do not translate directly to total product cost ($/ODt) because of the influence of average moisture content and bulk density, which vary by case study.
Feedstock.Quality
Feedstock quality is a primary consideration for the end user. Biomass consumers have built markets, customer relationships and processes that depend upon a reliable feedstock profile. Feedstock that falls outside expected parameters put the enterprise at risk.
CompositionBiomass components have differing feedstock characteristics depending upon their source. For example, wood has different characteristics from bark and from foliage. Some constituents are not
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desirable in some end-users processes. For example bark is undesirable in a wood pellet sold into a domestic market because it causes increased ash production. Delivering feedstock to market that does not match the expected composition will result in poor outcomes.
Moisture ContentMoisture content is the most significant variable in the handling and delivery phases of feedstock supply, and also has major implications in the processing. Water is heavier than biomass, and so each percentage point of moisture shipped with the biomass adds about 3-4 kg/m3 to the bulk density (Simpson 1993, page 8). If we assume that a 16 m (53 ft) high-boy chip van will hold 100 m3 and carries a maximum net weight of 20 tonnes, then the maximum bulk density of the feedstock should not exceed 200 kg/m3 to achieve the maximum energy value in the load (as measured by oven dry mass). However, bulk density of the ground material was measured as varying between 174 and 212 kg/m3 (green weight basis). Feedstock bulk density is sensitive to:
species (Douglas-fir wood has a higher specific density than lodepole pine, for example);growth rate (slow-grown wood has a higher proportion of late wood and therefore higher density);moisture content (both absorbed water and free water in the load); and particle size (coarser grinding yields less compactible feedstock, reducing bulk density).
Preliminary calculations show that moisture comprised between 22% and 31% of the bulk density (Table 4), and in two of the three case studies the material exceeded the critical bulk density of 200 kg/m3 (Table 4). This leads us to the conclusion that drier feedstock is more efficient to handle and haul, and we also have operator’s comments that dry material goes through the grinder more efficiently. Table 4 shows that bulk density is not solely determined by moisture content, but clearly an increase in the moisture content will increase the bulk density of the material, and therefore render handling and transport less efficient.However, we understand that feedstock can be too dry, resulting in trouble with material-handling in the receiving plant (too much dust, loss of fine material) and lack of anaerobic digestion that can be an important pre-treatment process.
Table 4: Moisture content, bulk density, and calculated estimates of the mass of the moisture and wood for three.case.studies
Case Study Moisture Content (% Wet Basis)
Bulk Density (kg/m3)
Estimated Mass of Fractions (kg/m3)
Moisture % of bulk
densityMean Mean Moisture Wood
1 31.5 206 47 159 23%2 29.8 174 46 166 22%
3(a) 39.1 212 54 120 31%
ContaminationContamination of feedstock can lead to significant quality control issues in the receiving plant, and must be a primary consideration for the grinding process.
Steel and other metals can damage processing equipment, and should be eliminated from the feedstock. Tire chains and other steel debris can get pushed into piles, grinder teeth can be broken and lost into the feedstock, and cable, saw chain, and other debris can be tossed away into cull piles.
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Dirt and rocks mixed into the infeed material or scooped up during the feeding and loading processes can damage processing equipment, and increase the ash content and clinkering (forming slag from the burning of minerals). These should be minimized.Garbage (e.g. plastic pails, oily rags, greasy material) deposited into the infeed material contaminates the feedstock with unwanted chemical constituents and may cause health concerns.
Biomass feedstock should be handled in the woods as a product with value, and stacked purposefully to minimize its contamination and maximize its quality.
Significant Lessons Learned
GrindingMaterial should be organized with grinding in mind. Working from round piles built for burning is inefficient because the material must be organized during the feeding process, increasing the infeed costs and reducing grinder efficiency. In addition, round piles are low density, meaning that the material to be ground is more dispersed, and grinder must therefore move more often. This ripples out to producing more smaller piles of chips, which decreases loading efficiency and increases losses. It is worth considering the benefit of organizing material in advance of grinding, to align the logs and concentrate the piles. Consider organizing piles in advance of grinding, to build tall piles within reach of the road, for rapid infeed loading and grinding directly into trucks.Wheeled grinders are limiting because they need to stand on a flat road. This limits the traffic that can pass the grinding operation, and means that material stacked back from the road needs to be forwarded to the grinder. Tracked grinders are less limiting because they can walk off the road, and the length of the grinder can accomplish the forwarding of the material to roadside. Moving between piles is easily accomplished with a tracked grinder, but is more difficult with a wheeled grinder using the equipment available on site.It is important to match the grinder configuration to the job underway. Wheeled grinders are best on roadside or semi-permanent central locations, whereas tracked grinders are more suitable for in-bush applications. Grinders are in limited supply, however, and it is not always possible to contract with a specific machine. This causes some difficulty if the work is organized for one type of grinder, but another is used.Grinding screens vary the proportion of fine versus coarse material in the product. Finer grinding has the benefit of increasing the bulk density of the material, making trucking more efficient, but slows the grinding process. Grinder plus infeed loader contract rates are substantially higher than truck rates, so we expect that grinder efficiency is more valuable than trucking efficiency.The size of the machine is an important determination. Larger grinders have higher throughput, but are less manoeuvrable. Smaller machines are best suited to smaller jobs or jobs with frequent movements. Very small hand-fed grinders have very limited application because of the labour cost of feeding the grinder.
Infeed LoadingButt-n-top loaders are superior to a bucket and thumb arrangement because they can rotate the infeed material.Organizing the material for grinding provides greater loading efficiency if the loader can rotate only 90 degrees.
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Grinding Case Study 3a.
Two loaders feeding a grinder.
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Working with two loaders to feed the grinder means that neither loader is operating at best efficiency, because they must each wait for the other to clear the infeed area.Loader operators must be vigilant for contamination -- rocks, steel, garbage, and snow all find their way into and through the grinder, causing damage in the grinder and at the receiving plant.
Truck LoadingIn case-study 1, 2, 3a and 3b the grinding phase was separated from the loading and trucking phase. This has the advantage of reducing waiting time for the trucks, but has several disadvantages.
An extra machine is required to load the chips from the ground.Depositing chips on the ground increases contamination with dirt, unground wood, and snow.Chip piles standing out in the weather will gain additional moisture through snow or rainfall.
Significant losses of ground material occur in an effort to minimize the contamination of the chips, and the authors estimate that 15 cm left on the ground from the bottom of the pile represents 11% of the chip volume.
Uneven ground surface (ruts, stumps, surface debris etc.) increases both contamination and losses.Chips left on the ground will restrict natural regeneration for a period of years, and may be difficult to plant through, increasing reforestation cost.
High-capacity grinders can fill a truck almost as fast as an excavator with a high-volume cleanup bucket. However, grinding directly into the trucks presents a different set of problems.
Planning ahead is required to organize the debris close enough to the road to be deposited directly into the truck from the grinder, bearing in mind that the truck must stay on the road.The grinder needs to stand perpendicular to the trailer it is filling. For roadside logging blocks, this eliminates the use of wheeled grinders because both grinder and trucks must stand on the road, meaning the truck and grinder are one behind the other. Co-ordination of trucks is critical to minimize grinder downtime while exchanging trailers. It is costly to have the grinder waiting for a trailer to fill, since the grinder plus infeed loader are the most expensive part of operation. A logical solution is to have extra trailers available with a tractor to tend the trailers through the loading phase, to divorce the trucking phase from the grinding phase.
TruckingManoeuvrability for trucks is a significant issue where snow banks, chip piles, grinders and pickup trucks all take up space and block truck access. Empty chip trucks have little weight on the driving wheels, and suffer from poor driving traction.Chip vans have long fixed trailers, which are difficult to turn around and do not back up well on narrow winding roads. Clearing sufficient space to allow trucks to pass each other and grinding or loading operations is important. Frequent turn-arounds are important, and are most productive if the truck can turn around without backing up.
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Unloading walking-floor trailer.
Loading feedstock from the ground, case study 3b.
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Circle routes in the bush are an optimum solution for chip trucks, but potentially increase site disturbance and disturb regenerating cutblock area. They do provide for an efficient queue at the loading site, minimizing loading time and downtime.Chip vans are lightly built and will not withstand rough handling by loaders like log trailers do. Standing on uneven ground can create strains in the chip van for which they are not designed, sometimes making it difficult to close rear doors.Drop-centre chip vans are lightly built and have very limited clearance, but the trailer-and-pup configuration improves their manoeuvrability. Roads must be flat and smooth with minimal vertical deflection to avoid high-centering.Bulk density of the feedstock and volume of the truck are each potentially limiting in the trucking operation. Dry compacted material will have the same volume and (perhaps) weight as wet loose material, but yields much better dry weight (and therefore energy) per trip. Treat the feedstock to minimize moisture content and maximize bulk density to improve trucking efficiency.Moisture content of the feedstock and outside ambient air temperature can combine to freeze chips into the vans. Chip piles that have been ground during warm daytime temperatures are well insulated and contain free water on the surface of the chips. Cold overnight temperatures chill the walls and floor of the chip vans, so that the free water freezes to the walls and floors, causing the chips to stick in the van, just like a child’s tongue on a steel post. The vans become disabled in the unloading area until the chips can be dug out manually.Expect delays at the unloading stage. Waiting in the unloading queue, or waiting for disabled dumping equipment is expected.Small grinding operations require different trucking options, and roll-off bins were employed successfully in case studies 4, 5 and 6. Roll-off bins (30 mRoll-off bins (30 m3) are over half the cost but only one third the volume of a conventional chip van. They work well for small volumes but they are costly.They work well for small volumes but they are costly.work well for small volumes but they are costly. - manoeuvrable over short distances - not economical over long distance – best kept within 20 km radius of the delivery point - works well with variety of smaller chippers/grinders - provide an option to stockpiling on ground between trucks - easy to store at most sites temporarily - reduces scheduling issues - easy to cover for moisture protection - minor issue with contamination – bins spotted on site may invite garbage, check prior to filling - spotting, moving, and pick-up is at the mercy of the trucking contractor
Winter OperationsSnow/ice contamination on both debris and chip piles increases moisture content.Wet material is well chilled during the unloading process, and freezes in the infeed pile at the receiving plant. This material remains very cold and necessitates much greater heat input to dry; reducing the energy efficiency of the processing.Snow plowing is an additional cost to open roads and pull-outs, and snow banks block access to piles and decking space, narrow the roads and hide ditches. Further snow plowing and ‘winging’ snow may bury stacked debris or chip piles.Sometimes its just too cold to operate, causing loss of productivity or equipment breakdown and operator fatigue.
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30 m3 Roll-off bin.
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Break-up is a difficult period with trucks breaking through winter roads, heavy grinders on thawing soils, contamination by mud, long shifts, imminent road bans, and a sense of urgency to complete that pushes workers to fatigue.
.Outstanding.Issues
It would be worthwhile to seek an optimized solution to the fineness of the grinding screen, which increases grinding cost but potentially reduces trucking cost.Specific gravity of the feedstock components is not well documented, and has a significant bearing on the payload capacity and energy out-put of potential wood supplies. A careful investigation of feedstock bulk density and the implications it has to energy output is important.Managing moisture content before and after comminution is important to the cost of production and the value of the material, but we have no experience in the methods of doing so. Investigate tarping options. Develop trucking systems that control truck waiting time but provide empty trailers for loading.Explore opportunities to densify the load while loading is under way, e.g. compaction, shaking, etc.
RecommendationsPlan at harvest stage to facilitate grinding operation
Alignment – butts to road (at time of logging)Plan ahead – think where chip piles need to be, adjacent to road or directly into trailersWithin short reach of loader, extended reach affects productivityMinimize movement and swing of feed loader Maximize height of debris piles – 4-5m – piles take up a lot of ground spaceSort piles at time of logging to maximize product value - Hog fuel - Pellet chip - Pulp chip
Re-pile older debris to maximize grinding operation using butt-n-top loaders to align material and stack it high in large piles.Manage the quality of the feedstock.
Don’t mix snow in with debris – affects moisture contentWatch for deleterious debris such as rocks, metal at time of deckingGrind directly into trucks -- not onto the ground.Cover debris piles to allow drying to equilibrium with ambient air Cover chip piles if left for long term field storage
Consider the fossil-fuel consumption of sourcing feedstock from the bush, and account for that consumption to support claims of carbon neutrality.
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�� UBC Alex Fraser Research Forest 2009
Conclusions
Feedstock production for the bioenergy industry is a new program in British Columbia forestry. At the initial stages the program has focused on the debris piles from earlier logging passes. Interface fuel reduction provides another opportunity to generate biomass within a short distance of bioenergy producers. We have examined seven case studies in the Williams Lake area to determine the cost of feedstock production and delivery, and consider the quality of the feedstock to the consumer. Costs of production have ranged widely, but there is considerable scope to reduce costs and improve quality. It is likely that feedstock production will become a part of normal timber harvesting operations in BC, and we will need to learn quickly to ensure viable operations.
References
Day, K., D. Skea and B. Carruthers. �00�. Mitigating the Effects of Mountain Pine Beetle on Wildfire Hazard within the City of Williams Lake. Contract Report to NRCan. ��pp.
Day, K. and M. Rau. �00�. Mitigating the Effects of Mountain Pine Beetle on Wildfire Hazard within the Cariboo Re-gional District. Contract Report to NRCan. ��pp.
Evans, R.L. �00�. Alternative energy technologies for BC. Pacific Institute for Climate Solutions. UVic. �� pp.
Koot, C. �00�. Grassland Benchmark Restoration at the Knife Creek Block: RP #0�-�� Implementation Report. Con-tract Report prepared for MOFR Cariboo-Chilcotin Range Branch. ��pp.
Sapinsky, S. and V. Groves. �00�. Scaling and billing of material manufactured into hog fuel or chips on the harvest area. BC Forest Service, Southern Interior Forest Region SOP No. REV 0��.
Simpson, W. ����. Specific gravity, moisture content, and density relationship for wood. USDA, For Serv. For. Prod. Lab, Gen. Tech.Rep. FPL-GTR-��. Madison Wisconsin. �� p.
�� UBC Alex Fraser Research Forest 2009
Appendix 1 -- Case Study Reports
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Case Study #1 - Grasslands Location:
Alex Fraser Research Forest, Knife Creek Cutblock 224 Co-ordinates:
Cycle time to plant: 2.6 hours includes chain-up, loading, unloading, trailer prep. (Tarping, un-tarping, unavoidable delays.) Distance to plant: 30.3 km one way
Clearcut with feller-buncher, grapple skidder to roadside. Processing at roadside for sawlog content only. No pulp sort at primary harvest. Logging debris piled for burning.
Comminution:
Peterson 4710B horizontal grinder, includes two excavators to feed grinder Owner: Del Kohnke Contracting., Kelowna, BC
Grinding productivity: 140 ± m3/hour (manufacturer’s suggested rate is 275 m3/hour) Loading productivity: 229 ± m3/hour Cost*: $ 25.77 /GMt grinding only $ 3.66 /GMt loading * includes mob/demob Hauling:
Trailer configuration: 53’ (16.2m) Tri-axle Walking Floor 110 m3 capacity or similar
Cycle time(s): to Pinnacle 2.5 hrs – 36 km and to EPCOR 2.9 hrs – 42 km. Cycle time includes chain-up, loading, unloading, trailer prep. (tarping, un-tarping), unavoidable delays.
Destination: Pinnacle Pellet (Williams Lake); EPCOR Williams Lake Power Plant (Williams Lake)
Owner(s): Cariboo Shavings 13 loads GMt from weigh scale
$ 7.63/GMt Truck configuration: highway tractor
Trailer configuration: 53’ (16.2m) Tri-axle Walking Floor 110 m3 capacity or similar Cycle time(s): to Pinnacle 1.9 hrs – 13.9 km and to EPCOR 1.8 hrs – 10.7 km. Cycle time includes chain-up, loading, unloading, and trailer prep. (tarping, un-tarping), unavoidable delays.
Destination: Pinnacle Pellet (Williams Lake); EPCOR Williams Lake Power Plant (Williams Lake) Product:
EPCOR – Williams Lake Power Plant hog fuel 11 loads 294 GMt Moisture content: 39.1%wet
Oven Dry Tonnes: 179 ODt
Figure 1 Dead Pine Overstory
Figure 2 Untreated on left - treated on right
Figure 3 Dry pine sort (Pile #2)
Figure 4 Grinding dry pine (Pile #3)
Figure 5 Hog piles (Pile #1)
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Case Study #3b – Williams Lake Airport Location: Williams Lake Regional Airport Co-ordinates: UTM: zone 10 563432E 5782436N Latitude: 52° 11’ 19” Longitude: 122° 04’ 19” Ecology: Biogeoclimatic zone: IDF subzone: dk3 Site series: 01 Forest Inventory Label: FPl, 100 year old stand Geography: aspect: flat slope: <5% average elevation: 930m Description: Harvest area – 6.72 ha Cruise: 119 m3/ha harvestable volume
Species content: 71% Douglas-fir, 19% Lodgepole pine, 5% Spruce, 4% Aspen Condition: Two sorts
dry – 30%estimate MC, dry pine green – 39.1%estimate MC, understory Douglas-fir Harvest Type: Partial cut – remove dead or dying pine, reduce density of smaller trees harvested winter 2009 Comminution:
Duratech 9564 horizontal grinder, includes one butt’n’top loader to feed grinder and one excavator with clean-up bucket to load trucks
Owner: Del Kohnke Contracting, Kelowna, BC Grinding productivity: 158 m3/hour (max. output 300 m3/hour)
Owner(s): unknown 35 loads 870 GMt from weigh scale
$ 6.33 /GMt Truck configuration: highway tractor
Trailer configuration: 53’ (16.2m) Tri-axle Walking Floor 110 m3 capacity or similar Cycle time(s): to Pinnacle 1.9 hrs – 13.9 km and to EPCOR 1.8 hrs – 10.7 km. Cycle time includes chain-up, loading, unloading, and trailer prep. (tarping, un-tarping), unavoidable delays.
Destination: Pinnacle Pellet (Williams Lake); EPCOR Williams Lake Power Plant (Williams Lake)
EPCOR – Williams Lake Power Plant Hog fuel 26 loads 674 GMt Moisture content: 41.7%wet
Oven Dry Tonnes: 393 ODt
Figure 1 Dry pine deck (Pile #3)
Figure 2 Green hog deck (Pile #2)
Figure 3 Grinding green hog deck (Pile #2)
Figure 4 Front pile is ground dry pine; back piles are green hog
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Case Study 4 Fox Mountain Fuel Treatment Location: Fox Mountain Road Co-ordinates: UTM: zone 10 560800E 577670N Latitude: 52° 08’ 21” Longitude: 122° 06’ 38” Ecology: Biogeoclimatic zone: IDF subzone: dk3 Site series: 01 Forest Inventory Label: F, 160 year old stand Geography: aspect: Southwest slope: 6% average elevation: 924m Description: Harvest area: 6.4 ha Cruise: n/a
Sawlog volume: n/a Bulk debris: 507± m3 in 18 small piles
Species content: 95% Douglas-fir, 1% Lodgepole pine, 4% Aspen Condition:
green - 40%estimate MC, harvest winter 2009, predominantly understory Douglas-fir and aspen
Harvest Type: Partial cut – remove dead or dying Douglas-fir, reduce density of smaller trees Comminution: Truck mounted Beast Bandit 2680 horizontal grinder with picker unit Owner: EVS Wood Reduction, Kelowna, BC
Green - 40%estimate MC, harvest winter 2009, predominantly lodgepole pine and aspen Harvest Type:
Partial cut – remove dead or dying pine, reduce density of smaller trees Comminution: Truck mounted Beast Bandit 2680 horizontal grinder with picker unit Owner: EVS Wood Reduction, Kelowna, BC
Green - 40%estimate MC, harvest winter 2009, predominantly lodgepole pine and aspen Harvest Type: Partial cut – remove dead or dying pine, reduce density of smaller trees Comminution: Truck mounted Beast Bandit 2680 horizontal grinder with picker unit Owner: EVS Wood Reduction, Kelowna, BC
