Juha Laitila

Productivity of Stump Harvesting for Fuel

Abstract The productivity of harvesting stump and root wood was studied in Norway spruce (Picea abies) stands. The objective was to create productivity models (m3/E0h) for stump wood extraction, stump wood forwarding, and site preparation, in addition to identifying work phases and improvement opportunities in the extraction and forwarding chain. Productivity models were based on time studies with professional operators. The independent variables in stump wood extraction were stump diameter (cm) and the number of stumps per hectare. For forwarding, the independent variables were volume of stump wood removed (m3/ha) and forwarding distance (m). When removing 350 stumps per ha with an average diameter of 40 cm, productivity was estimated at 7.9 m3/E0h. Increasing the number of stumps removed from 350 to 800 stumps per ha, increased productivity to 10.8 m3/E0h. Forwarding productivity was 7.8 m3/E0h with a forwarding distance of 250 m and a load size of 7.0 m3 when removing 60 m3 of stumps per ha.

Forwarding of Whole Trees After Manual and Mechanized Felling Bunching in Pre-Commercial Thinnings

Abstract This paper examines the forwarding productivity of energy wood thinnings. The objectives of the study were to: compare the forwarding productivity following either manual or mechanized felling of whole trees and create productivity models for forwarding. The time consumption of the work phases in forwarding, following manual and mechanized cutting, was formulated by applying a regression analysis, in which the independent variables were cutting removal (m3/ha) and forwarding distance (m). The final calculation unit for time consumption in each of the work elements was second (s) per solid cubic meter (m3). Time studies were carried out using two Timberjack 810B forwarders. According to these results, forwarding productivity following mechanized energy wood cutting was significantly higher compared to productivity after manual cutting. Mechanized cutting by the harvester enables the felling and bunching of whole trees into large grapple loads close to the side of the strip road, which clearly improves the output of forwarding thereby helping to reduce costs. When the forwarding distance was 250 m, accumulation of energy wood was 60 m3/ha, and load size was 6 m3, the forwarding productivity following mechanized cutting was 11.9 m3/E0h and 7.1 m3/E0h after manual cutting.

Productivity of whole-tree bundler in energy wood and pulpwood harvesting from early thinnings

Abstract First thinnings have been neglected to great extent in Finland because of high harvesting costs. The whole-tree bundler (Fixteri) was developed in order to rationalize the integrated harvesting of small-diameter energy wood and pulpwood and to reduce transportation costs through load compaction. The operation of the whole-tree bundler is composed of cutting and compaction processes. In the present study, the productivity level and the performance characteristics of the second version of the whole-tree bundler (Fixteri II) in integrated energy wood and pulpwood harvesting from first thinnings were defined on the basis of a time study. When the mean volume of removed whole trees averaged 20 dm3 at the stand, the productivity of Fixteri II per effective working (E0 excluding delays) hour was 3.4 m3/(E0) and with an average removal of 75 dm3, it was 6.1 m3/(E0). When compared with the first prototype of the whole-tree bundler (Fixteri I), the productivity of Fixteri II was 38–77% higher, depending on the stand density and mean tree volume of the removal. The higher performance level of Fixteri II stemmed mainly from the increase in multi-tree cutting and from the introduction of grapple feeding of the bunches. Furthermore, the better hydraulic capacity of the base machine enabled a higher level of simultaneous working processes.

Variation in age, annual usage and resale price of cut-to-length machinery in different regions of Europe

ABSTRACT The high price of cut-to-length machines requires careful planning of investment in new or second-hand machines. The investment is influenced by machine usage, and is also affected by maintenance, insurance and repair costs, harvesting conditions, number of machine relocations, and availability of working opportunities and employment. In this study, age, size, annual usage and price of the cut-to-length harvesters and forwarders for sale in Europe was investigated, using sales data from the online marketplace. The average age of harvesters was 7.3 years and the average age of forwarders was 7.5 years. The newest machines were on offer in the Northern countries (6.5 and 6.1 years for harvesters and forwarders, respectively). The oldest harvesters were on offer in Western Europe (8.1 years) and Eastern Europe (8.2 years) and the oldest forwarders in Eastern Europe (9.9 years). The average annual use of both harvesters and forwarders were notably high in the Baltic and Northern countries compared to the Western and Eastern Europe. On average, the annual use was 1759 and 1913 h year−1 for the harvesters and forwarders, respectively. The average resale price of harvesters was more dependent on age than total use. For forwarders, both age and total usage had a similar explanatory value. For newer CTL machines, aged between 1 and 5 years, the bigger size class of the machine corresponded to higher price. Older machines did not exhibit such correspondence, whereas the annual usage showed high correspondence on the resale value of the machine.

Using the ComBio decision support system to assess whether energy wood and/or pulpwood should be harvested in young forests

The operational environment of forest-chip procurement in Finland is challenging, because increasing production is raising the costs due to the limited availability of biomass. Integrated harvesting of industrial roundwood and energy wood is one solution to lower the costs of biomass procurement from young forest stands. In addition, integration creates flexibility for operations management because the procurement can be adjusted to meet the current demand for wood biomass. The recovery options of young forest thinning consist of pure industrial roundwood, pure energy wood, and integrated harvesting of both industrial roundwood and energy wood. However, without calculation tools, the outcomes of the alternative recovery options are difficult to see before operations have been carried out, because operational variables such as bucking diameter and bolt length have a direct influence on the accumulation of roundwood and energy wood. This article presents the ComBio decision support system, which can be used to produce information considering biomass recovery options, compare these options, and support selection among them. ComBio’s structure, input data, model estimation procedure, and methods for comparison and decision support are introduced. Finally, a demonstration of ComBio is carried out with sample forest data.

A GIS-based comparison of long-distance supply of energy wood for future needs from young forests to the coast of Finland

With increasing demand and competition for forest biomass, the future will see its transportation distances increase in Finland. The aim of the study was to evaluate long-distance transportation solutions and intermodal handling of energy wood for its journey from young forests to a combined heat and power plant in Kokkola, Finland. Via a case study, the costs of various supply chains were estimated on the basis of spatially explicit data. The potentials were estimated from National Forest Inventory data. With GIS assistance, supply points were determined, and supply costs with nine distinct supply chains were calculated for each point on the basis of transport distances and productivity models. Both whole-tree and delimbed stemwood chains were included. The transport modes considered were trains, traditional 60-tonne trucks, and combinations with new high-capacity transport (HCT) vehicles of 68 and 76 tonnes and train transportation. Whole trees were assumed to be transported either as chips or in uncomminuted form to train terminals, whereas delimbed stemwood remained uncomminuted. Use of interchangeable containers was assumed in two of the whole-tree chains. In our study, the whole-tree supply chains did not prove to be competitive with the stemwood chains. Train-based chains proved to be cost-competitive with the traditional truck chain only in very limited areas around the terminals. The costs of the supply chains based on use of HCT vehicles were always lower than the costs associated with the train-based chains. The greatest barrier in long-distance and intermodal transport of forest chips is the high cost of transport by rail.

Alternative operation models for using a feed-in terminal as a part of the forest chip supply system for a CHP plant

The fuel supply of forest chips has to adapt to the annual fluctuations of power and heat generation. This creates inefficiency and unbalances the capacity utilization of the fuel supply fleet in the direct fuel supplies from roadside storages to power and heat generation. Terminals can offer an alternative approach for the fleet management of fuel supplies in terms of smoothing the unbalanced fleet use towards more even year‐round operations. The aim of the study was to compare the supply costs of a conventional direct forest chip supply to an alternative fuel supply with the use of a feed‐in terminal using the discrete‐event simulation method. The influences of the terminal location, terminal investment cost, outbound terminal transport method, terminal truck utilization and quality changes of terminal‐stored forest chips for the fuel supply cost were studied in the case environment. By introducing a feed‐in terminal and a shuttle truck for the transports of terminal‐stored forest chips, the total supply cost was 1.4% higher than the direct fuel supply scenario. In terminal scenarios, the supply costs increased 1–2% if the cost of the terminal investment increased 30%, the distance to the terminal increased from 5 to 30 km or the total annual use of a terminal truck decreased 1500 h. Moreover, a 1 per cent point per month increase in the dry matter loss of terminal‐stored chips increased the total supply cost 1%. The study revealed that with the relatively low additional cost, the feed‐in terminal can be introduced to the conventional forest chip supply. Cost compensation can be gained through the higher annual use of a fuel supply fleet and more secured fuel supply to power plants by decreasing the need for supplement fuel, which can be more expensive at a time of the highest fuel demand.

Hybrid solutions as a measure to increase energy efficiency – study of a prototype of a hybrid technology chipper

ABSTRACT The objectives of this study were to examine the new hybrid technology chipper, Kesla C 860 H in comparison to two conventionally diesel-powered chippers, when chipping conifer pulpwood and logging residues. Productivity, fuel consumption and quality of the chips were measured and analyzed. During the time studies, both the chipper and hybrid system were working well. Chip quality was good and met the demands of small-scale residential boiler users. The average chipping productivity of the hybrid chipper unit was 13.1 oven dry metric tonnes (odt) per effective hour (E0h) when chipping logging residues and 11.3 odt E0h−1 when chipping pulpwood. This was lower than for the conventional chippers which produced 20.1 odt E0h−1 when chipping logging residues and 31.2 odt E0h−1 and 14.0 odt E0h−1 when chipping pulpwood. Fuel consumption of the hybrid chipper was 2.9 litres per odt for logging residues and 3.1 litres per odt when chipping conifer pulpwood, which was slightly lower than for the conventional chippers. Compared to conventional chippers, the hybrid chipper was more energy efficient and consequently produced the least amount of emissions per odt of chips. The productivity results of this study must be considered with care as the chipper and especially the hybrid system are under continuous development, and follow-up studies are needed to determine long-term productivity, fuel consumption and operating costs.

Esitutkimus rankahakkeen keinokuivaukseen perustuvan hankintaketjun kustannuskilpailukyvystä

Seloste artikkelista: Laitila J., Ahtikoski A., Repola J., Routa J. (2017). Pre-feasibility study of supply systems based on artificial drying of delimbed stem forest chips. Silva Fennica vol. 51 no. 4 article id 5659. https://doi.org/10.14214/sf.5659