• Energy Research

A new chipper-truck was developed for extending the benefits of industrial chipping to space- constrained landings, normally inaccessible to industrial operations. The new machine was taken for a European test tour, so that it could be tested under conditions considered typical of Mediterranean, Alpine, Central and Nordic Europe. The same machine and operator were used for all tests, which lasted 65 h and produced over 100 chip containers. Productivity varied between 13 and 19 tonnes of green chips per scheduled hour, inclusive of all delays. Fuel consumption ranged from 1.8 to 2.8 dm3 of diesel per tonne of green chips. Machine utilization ranged from 68 to 89%, and it was highest in the Nordic trials, due to the use of pre-parked containers, which dramatically reduced the occurrence of interaction delays. Regional differences were only related to operational layout and organization, which set the Nordic trial apart from all others. Knife wear and screen size had a major impact on chipper performance. The same accounted for cut length. Production of small chips is only justified when the market offers premium prices for this assortment.

Abstract Maritime transport facilitates trade with bioenergy feedstocks in the Baltic region. The study aims to provide guidance on efficient organisation of logistics at the port of loading for maritime transport of wood chips. The economic effects of using an intermediate terminal as opposed to direct delivery to port were studied, as well as the relationships between production capacity and storage capacity. Discrete-Event Simulation was used to analyse scenarios where a variable part of the volume is handled through the terminal. The total supply cost, including chipping, transportation, storage and handling at inland terminal and port, as well as loading of the ship, varied between €6.73 and 7.85 per MWh in the different scenarios. The volume passing through the terminal had a significant influence on total cost, showing a supply chain cost increase of €0.78 per m3 (approximately €4.67 per dry tonne) for material delivered through the terminal. The difference in storage cost between port and inland terminal determines whether the terminal volumes affect costs, which was shown by a sensitivity analysis. Even so, the terminal offers a possibility to manage uncertainty, both in production rates and in shipping date, and influences the supply network. The main advantage of using a simulation technique for planning production and logistic flows is the visualisation of risks and margins.

Since the late nineteenth century when high-cost equipment was introduced into forestry there has been a need to calculate the cost of this equipment in more detail with respect to, for example, cost of ownership, cost per hour of production, and cost per production unit. Machine cost calculations have been made using various standard economic methods, where costs have been subdivided into capital costs and operational costs. Because of differences between methods and between national regulations, mainly regarding tax rules and subsidies, international comparisons of machine costs are difficult. To address this, one of the goals of the European Cooperation in Science and Technology (COST) Action FP0902 was to establish a simple format for transparent cost calculations for machines in the forest biomass procurement chain. A working group constructed a Microsoft Excel–based spreadsheet model which is easy to understand and use. Input parameters are easy to obtain or possible to estimate by provided rules of thumb. The model gives users a simultaneous view of the input parameters and the resulting cost outputs. This technical note presents the model, explains how the calculations are made, and provides future users with a guide on how to use the model. Prospective users can view the model in the Supplementary Material linked to this article online.

Abstract Declining market prices make it necessary to reduce supply costs of forest chips to ensure profitability in the supply chain and a continued supply of forest chips to the energy industry. Comminution and transport are two of the major contributors to the total costs in the forest fuel supply system. In order to fully utilise truck payloads and reduce transport costs, logging residues are usually chipped at the landing. For the chipping contractor, it is important to maximise the proportion of effective work time in relation to scheduled work time. Currently it is not uncommon that effective work time is less than 50 per cent of scheduled work time, due to chip transports using the chipper, waiting for chip trucks, and other delays. Increased chipper utilisation requires greater coordination between the chipper and the chip trucks transporting the produced chips to the customer. Supply systems have been simulated to examine how transport distance, number of trucks, shift scheduling and chip buffers affect the system costs for a high-performance chipper system. System costs and machine utilisation vary greatly, depending on system configuration. It is always beneficial to have six containers in the buffer on the landing rather than three, and trucks should begin their shifts at one-hour intervals. To maximise chipper use and minimise system costs, four container trucks are needed if the transport distance exceeds 50 km. However, the large seasonal fluctuations in demand for biomass chips makes it hard to fully utilise the potential of the system over the whole year. The study concludes that it is important to regard chipping and chip transport as one operation, not two separate ones, as they are so dependent on each other.

Abstract Storage is an important component in securing the supply chain for forest fuels, but can result in substantial dry matter and energy losses that reduce the economic value of the material. This study examined fuel quality and amount of recovered energy during storage of forest-residue chips stored in a full-scale pile and the effect of covering the pile with a water-resistant, vapour-permeable fabric. Moisture content in the covered part declined continuously during the trial, while mean moisture content in the uncovered part did not change, due to rewetting at the surface. Average dry matter losses after seven months were 5.8% in the covered part and 7.3% in the uncovered part. Combined changes in fuel quality and dry matter decreased the amount of assessable energy (expressed as net calorific value as-received from an initial kg of dry base) by 5.3% in the uncovered part and 0.6% in the covered part. Thus covering the pile with a semi-permeable fabric provides opportunities to store wood chips at lower cost.

Acknowledging the absence of up-to-date empirical data on the value retention, service life and annual use of chipping machinery, in 2017 the authors surveyed the records kept by 50 contractors offering biomass chipping services. The machine fleet and operations in this survey could be taken as representative for most of Europe, where the biomass sector is well established and is facing further expansion. Data collection included the whole chipping unit, comprised of chipper, carrier and loader. Manually-fed units were excluded from the survey. The data pointed at a service life up to and exceeding 10,000 h and 10 years, which relieved any concerns about poor durability. Value retention was good, and may exceed that of other mainstream forestry equipment. Engine power was the main explanatory variable in any models to predict purchase price and productivity. The effect of this variable could explain most of the variability (>80%) in the purchase price and productivity data. Results also pointed at the essential equivalence in price and productivity between PTO-driven (i.e., tractor powered) and independent-engine chippers, once differences in engine power are accounted for. However, the distribution of purchase price between different components of the chipping unit was different between the two unit types, with the chipper accounting for a larger proportion of the total investment in independent-engine units. Machine power was also different, with most PTO-driven units being significantly smaller than independent-engine units, due to the limitations of existing tractors. Furthermore, half of the carriers assigned to a PTO-driven unit were subject to flexible use, i.e., they were not solely used for chipping work.

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 conventiona...

Earlier studies have highlighted the importance of quality and quantity in forest fuel supply chains, since these parameters affect product value and handling properties, but both are constantly changing over time. Great monetary losses can be incurred if forest fuel material has to be delivered to end-users in non-optimal condition, e.g. to meet seasonal fuel demand with its large short-term variations. Thus earlier studies have also highlighted the importance of more information on the forest fuel supply chain. This paper describes development of a model for Weather-driven Analysis of Forest Fuel Systems (WAFFS) that can be used when analysing forest fuel supply chains and that accounts for both active machine activities and passive activities such as quality changes during storage. The aim was to develop a methodology that can be used to evaluate forest fuel supply chain scenarios and analyse various delivery strategies under different conditions. Application of WAFFS to evaluate delivery strategies for forest fuels showed that system improvements were possible when the right biomass was delivered at the right time. The WAFFS model gives an overview of biomass actually stored at different geographical locations and places (heaps or windrows) in terms of both quality and quantity. Delivery strategies actively prioritising biomass storage proved capable of delivering more energy when most needed, thereby improving yearly machine utilisation for contractors in the supply chain.