Lauri Sikanen

Precision measurement of forest harvesting residue moisture change and dry matter losses by constant weight monitoring

The moisture content of forest-wood chips is one of the most important quality factors for the rapidly growing bioenergy sector. Rising transportation costs and increased use of forest biomass for energy are forcing biomass suppliers towards better moisture-content management in the supply chain. In the literature, numerous studies on natural drying of forest biomass have been conducted based on traditional sampling of piles or weighing. The latest methodology for moisture-change monitoring has been constant weighing of piles in racks built on load cells. In this study, seven piles of logging residues were monitored for between 35 and 85 weeks in Finnish climatic conditions. In addition, two small piles which imitated drying in stand conditions were monitored for 6 weeks. After 8 months of drying, a remarkable dry-matter loss was observed in the logging residue piles.

Estimating the Characteristics of a Marked Stand Using k-Nearest- Neighbour Regression

The purpose of this study was to develop the k-nearest-neighbour method as a wood procurement planning tool. Traditionally, sampling measurement of standing trees has been used to obtain advance information on marked stands. In this study, key figures such as sawtimber/pulpwood ratio in pine and spruce stands, diameter and height distribution in spruce stands, diameter and quality distribution in pine stands, and quality distribution by diameter classes in pine stands were estimated using k-nearest-neighbour regression. The material consisted of 716 stands. Stands were located in the eastern Finland. Information regarding every stand was collected from the information system of one large Finnish timber-procurement organization. The accuracy of the k-nearest-neighbour method was compared with the traditional planning inventory method and stand inventory method. The created model was found to be a useful tool in the planning of wood procurement.

Impacts of logging residue and stump removal on nitrogen export to a stream: A modelling approach

Abstract The use of forest chips for energy can decrease net carbon emissions to the atmosphere, but harvesting logging residues and stumps may have adverse effects on the environment, including changes in nutrient export to water-bodies. The aim of this study was, with the aid of a computer model, to simulate the effects of logging residue and stump removal on nitrogen (N) export from a clear-cut area to a stream. A spatially semi-distributed FEMMA ecosystem model (tool for Forestry Environmental Management) was used to simulate N export from a catchment subject to clear-cutting and four different scenarios of logging residue and stump removal. These scenarios were compared with a conventional clear-cutting scenario, where the logging residues were left on site. Simulations suggested that the logging residue recovery does not decrease N export to the stream. In the model this was explained by a decrease in microbial immobilization, which in the case of conventional clear-cutting reduces net release of N in decomposition and mitigates the export of N. The decrease in immobilization is directly related to the removal of the woody debris from the site. Simulations suggested that harvesting of logging residues in low atmospheric N-deposition areas is not an effective strategy for reducing N loads in water-bodies.

Identifying and rating cultural sustainability indicators: a case study of wood-based bioenergy systems in eastern Finland

Cultural sustainability has become a much discussed topic in the forestry and bioenergy sectors. However, there are not many indicators available for measuring cultural sustainability. In order to identify indicators for the assessment of the cultural sustainability impacts of wood-based bioenergy in eastern Finland, two-phased expert interviews were conducted. The process was supported by a hybrid approach: A qualitative mapping technique was applied when the indicators were identified, and weights for the indicators were set using a quantitative rating technique. The experts identified 49 indicators of cultural sustainability. Most of the generated indicators were relevant for local uses and highlighted the perceptions of the general public. Furthermore, most of the indicators were relevant from the perspective of raw material acquisition. Applying methods of differing backgrounds enabled advanced problem structuring, which allowed the identification of indicators suitable for assessing cultural sustainability of wood-based bioenergy in Eastern Finland. The quantitative rating technique enabled the determination of the importance of the indicators generated. Nevertheless, it seems that the hybrid approaches have many challenges related to the quantitative measuring of the participants’ perceptions. Cultural sustainability indicators should be identified within a case study, since it seems that most of the cultural sustainability indicators are case specific. The process introduced here offers steps for identifying case-specific cultural sustainability indicators; however, the concept of cultural sustainability cannot be strictly defined.

Feasibility of Excavator-Based Harvester in Thinnings of Peatland Forests

Abstract In the next twenty years in Finland, annual cuttings on peatland forests are foreseen to increase by up to 30 % of the total cuttings. Cost effective harvesting methods on low yield peatland forests coupled with low ground bearing capacity are required. One solution to improve the feasibility of harvesting could be excavators tailored for forestry use and equipped with a harvesting head. In the study, cost competitiveness and productivity of the excavator-based harvester were investigated. The cost analysis focused on operating hours of harvester use, shift arrangements and purchase prices for the base machine and harvesting equipment when the base machine was used partly as a harvester and an excavator. Results were compared to conventional wheeled harvesters. If the base machine is used more than 3 working months as a harvester in addition to normal (6–8 months) excavator work, the harvesting method would be cost competitive compared to purpose-built harvesters (if 1 V and 2 shift arrangements were used). The 25 % increase of the base machine’s and harvester equipments’ purchasing costs did not eliminate the cost competitiveness of harvesting, when harvesting was carried out in 1 V shifts for at least 4 months. It would be feasible and profitable to invest in harvesting equipment for the excavator and therefore diminish the winter lay-days of the base machine by utilizing it in logging operations. Conditions on peatland sites mean that during the winter time the use of the excavator-based harvester is ideal, when the utilisation of all logging machines is at its highest.

Reengineering business processes to improve an integrated industrial roundwood and energywood procurement chain

Procurement systems and supply chains for industrial-scale forest fuel recovery are still immature. Business process improvement techniques can significantly improve system performance. The present study applies business process modeling and reengineering approaches to an integrated industrial roundwood and energywood supply chain in Germany. The existing business process was reengineered. A new business process for integrated industrial roundwood and energywood procurement and two new business processes for future biomass procurement operations were designed using proven best practices. The improvement potential of the new business processes was investigated by determining the organizational and managerial workload of all actors using discrete-event simulation. The results of the discrete-event simulation were then used as a basis for a comprehensive cost calculation. Finally, the cost-saving potential relative to the current practice was determined. The redesign of the current business process provides a cost-saving potential of 20–39% (–2.64 to –5.25 USD/m3). The first biomass procurement process involves a saving potential of 12–53% (–1.60 to –7.20 USD/m3), while the second might even increase the costs by 13% if the probability of failures is high. With decreasing probability of failures, the costs can decrease by up to 32% (+1.76 to –4.27 USD/m3). The study demonstrates that simple and low-cost measures can improve business processes in forest supply chains and achieve considerable cost savings.

Small Scale Pilot Combustion Experiments with Wood Pellets – The Effect of Pellet Length

The primary objective of this study was to observe the effect of pellet length on utility and combustion temperature. Pellets with various lengths were combusted in a pellet stove. Pellet length was found to have a significant effect on the combustion temperature and stability. Increasing the length of pellets from 5.8mm to 13.1mm decreased the average burning temperature by 31% and flue gas temperature by 25%. The major determinants of combustion efficiency derived from pellet length were assessed.

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.

Weather based moisture content modelling of harvesting residues in the stand

Harvesting residues collected from the final cuttings of boreal forests are an important source of solid biofuel for energy production in Finland and Sweden. In the Finnish supply chain, the measurement of residues is performed by scales integrated in forwarders. The mass of residues is converted to volume by conversion factors. In this study, weather based models for defining the moisture content of residues were developed and validated. Models were also compared with the currently used fixed tables of conversion factors. The change of the moisture content of residues is complex, and an exact estimation was challenging. However, the model predicting moisture change for three hour periods was found to be the most accurate. The main improvement compared to fixed tables was the lack of a systematic error. It can be assumed that weather based models will give more reliable estimates for the moisture in varying climate conditions and the further development of models should be focused on obtaining more appropriate data from varying drying conditions in different geographical and microclimatological locations.

Dry matter losses and their economic significance in forest energy procurement

ABSTRACT The value chain of forest biomass for energy always includes storing of the biomass. Biomass in natural conditions is always exposed to biological processes, some of them harmful. Dry matter losses caused by biological processes, such as composting and decaying, were studied by the weight monitoring method. After defining dry matter losses as 0.07–1.52% per month for small size delimbed roundwood under study, the total amount and economic scale of losses were calculated to gain an understanding about the phenomenon from the value chain management point of view. Losses during energy wood storing may be significant even with 3–6 months of storing. With 1-year storing time, economic losses varied between 91,000 and 373,000 euros, if the amount stored is 100,000 m3. The economic losses were 4–17% of the energy wood procurement costs, depending on the storage time, raw material and dry matter loss rate. Energy content of the storage can increase during the 12-month storage period if the dry matter losses are low, which requires careful storage management of energy wood.