Dimitris Athanassiadis

Energy consumption and exhaust emissions in mechanized timber harvesting operations in Sweden

The study presents an estimation of the energy input and the amount of emissions to air due to fuel, chainsaw and hydraulic oil consumption by heavy duty diesel engine vehicles operating in forest logging operations in Sweden. Exhaust concentrations are given for carbon dioxide, carbon monoxide, nitrogen oxides, hydrocarbons and particulate matter. Three fuel types (rapeseed methyl ester, environmental class 1 and environmental class 3 diesel fuels) and two types of lubricating base oil (mineral- and vegetable-based) were examined. Energy input per unit of timber production (m3ub) was 82 MJ, 11% of which was due to energy consumption during the production phase of the fuel. Emissions during the whole life cycle of the fuels and the base oils are included in the study. The highest CO2 and NOx emissions occurred when rapeseed methyl ester was used as fuel together with rapeseed as base oil for chainsaw and hydraulic oil. The highest HC and CO emissions occurred when environmental class 3 diesel fuel was used.

Fuel, Hydraulic Oil and Lubricant Consumption in Swedish Mechanized Harvesting Operations, 1996

Abstract When subjecting forest products to certification the total environmental load of wood harvesting machinery should also be assessed. In this study fuel hydraulic oil and lubricant consumption in harvesting operations in Sweden has been examined by using machine data acquired through a questionnaire. The objectives of the study were to assess the contractor and forest company owned harvesters’ and forwarders’ average oil consumption in practical harvesting operations in Sweden, ascertain if the ownership and size of the machines give different consumption figures and estimate the use of environmentally acceptable hydraulic oils as well as the amount of oil spilled outdoors. Diesel consumption was found to be 9351/1000 m3 ub for forwarders and 1 1671/1000 m3 ub for single-grip harvesters. Hydraulic, transmission and chainsaw oil consumption was significantly higher in forest company owned harvesters while no significant differences were observed among forwarders. Hydraulic oil spillage was estimated...

Pine and spruce stump harvesting productivity and costs using a Pallari KH 160 stump-lifting tool.

Abstract Even though stumpwood may become a significant part of the future fuel mix for combined heat and power plants in Sweden, the harvesting of stumps after regeneration felling is still only performed on a trial basis. Results from time studies on two, 23 tonne, excavators fitted for stump lifting, together with follow-up data on stump lifting and forwarding, are presented. Lifting, splitting, and piling the stumps accounted for 17, 32, and 32%, respectively, of the total productive work time. A predictive model was developed to estimate operational times and productivities when lifting pine and spruce stumps. Stump diameter, species, and terrain conditions contributed significantly to the fit of the model. The model predicts that productivity of stump lifting in spruce sites with easy terrain conditions and average stump diameters of 20 and 40 cm will be 1.23 and 4.19 oven-dry tonnes (ODT) per productive work hour, respectively. This is 43% higher than in pine sites with difficult terrain conditions and the same diameters. In the follow-up data, the productivity in stump lifting varied from 1.5 to 2.9 ODT per productive work hour while the cost for lifting and extraction to roadside varied from 37.8 to 59.4 €/ODT.

Energy use and emissions due to the manufacture of a forwarder

The aim of the study was to assess the amount of energy input and emissions of CO2, CO, NOx, SOx, N2O, HC, CH4 and particles discharge to the environment in association to the following stages of a forwarders life cycle; (1) material premanufacturing, (2) fabrication of individual components, (3) assembly of the vehicle, and (4) associated transports. The premanufacturing phase accounted for 65% of the total energy consumption, 70% of the CO2 emissions, 95% of CO emissions and 65% of the NOx emissions. Transports showed the smallest contribution to the environmental impact among the forwarder life cycle phases examined.

Path tracking in forest terrain by an autonomous forwarder

Abstract Autonomous navigation in forest terrain, where operation paths are rarely straight or flat and obstacles are common, is challenging. This paper evaluates a system designed to autonomously follow previously demonstrated paths in a forest environment without loading/unloading timber, a pre-step in the development of fully autonomous forwarders. The system consisted of a forwarder equipped with a high-precision global positioning system to measure the vehicles heading and position. A gyro was used to compensate for the influence of the vehicles roll and pitch. On an ordinary clear-cut forest area with numerous stumps, the vehicle was able to follow two different tracks, three times each at a speed of 1 m s−1, with a mean path tracking error of 6 and 7 cm, respectively. The error never exceeded 35 cm, and in 90% of the observations it was less than 14 and 15 cm, respectively. This accuracy is well within the necessary tolerance for forestry operations. In fact, a human operator would probably have a hard time following the track more accurately. Hence, the developed systems function satisfactorily when using previously demonstrated paths. However, further research on planning new paths in unknown unstructured terrain and on loading/unloading is required before timber transports can be fully automated.

Characteristics of Swedish forest biomass terminals for energy

Forest biomass terminals provide diverse services to the forest industry: buffer storage, transfers of material between different modes of transport, raw material upgrading, etc. Terminals’ operational costs are highly sensitive to their layout and design. In order to design efficient terminals, it will be essential to understand the current state of forest terminals. To this end, a survey was sent out to companies operating forest terminals for energy in Sweden. The respondents were asked to provide information about their terminals’ areas, volumes of material handled, equipment, inventory methods and age. The terminals were grouped into four size classes according to their surface area. Most terminals covered < 5 ha; terminals in this class accounted for 65% of the country’s total terminal area. In addition, more than half the country’s total forest biomass output was handled at terminals of <2 ha. The extent of paving at terminal size classes varied widely from 28 to 60%. Studied terminals handled 14 different assortments; on average, each individual terminal handled 2.4–4.0 assortments. The most widespread assortment was energy wood which accounted for 63% of the total volume handled. Larger terminals were older, often had better measurement equipment than smaller ones and relied more heavily on third parties to perform inventories. Conversely to big terminals, smaller terminals were more likely to have mobile machinery. Our results provide a detailed overview of the state of Sweden’s forest terminals and will be useful in the design of improved biomass terminals in future.

Bioenergy futures in Sweden - system effects of CO2 reduction and fossil fuel phase-out policies

Bioenergy could contribute both to the reduction of greenhouse gases and to increased energy security, but the extent of this contribution strongly depends on the cost and potential of biomass resources. For Sweden, this study investigates how the implementation of policies for CO2 reduction and for phase out of fossil fuels in road transport affect the future utilization of biomass, in the stationary energy system and in the transport sector, and its price. The analysis is based on the bottom‐up, optimization MARKAL_Sweden model, which includes a comprehensive representation of the national energy system. For the analysis, the biomass supply representation of MARKAL_Sweden is updated and improved by the use of, e.g., forestry forecasting modeling and through construction of detailed biomass supply curves. A time horizon up to 2050 is applied. The results indicate a potential for significantly higher use of bioenergy. In the main analysis scenario, in which CO2 reduction of 80% by 2050 is imposed on the Swedish energy system, the total bioenergy utilization increases by 63% by 2050 compared to 2010. The largest increase occurs in the transport sector, which by 2050 accounts for 43% of the total primary bioenergy use. The high demand and strong competition significantly increase biomass prices and lead to the utilization of higher cost biomass sources such as stumps and cultivated energy forest, as well as use of pulpwood resources for energy purposes.

Assessing Material Consumption Due to Spare Part Utilization by Harvesters and Forwarders

Abstract The aim of this study was to i) develop and examine a methodology to handle spare part utilization data for work machinery for future inclusion into a life cycle assessment study and ii) assess the material consumption per 1000 m3ub harvested and transported to the roadside due to spare part utilization by three types of forest machinery. Thirteen forwarders, 14 single-grip harvesters and 10 two-grip harvesters operating in northern Sweden were followed up by repair records that covered a period from half a year up to 3.5 years. The replaced machine components were sorted in seven material categories - steel and iron, aluminum, other metals (brass, copper), plastics, rubber, glass and batteries. Two scenarios with different assumptions on the consumption of saw chains, guide bars and tires were developed. According to the low scenario about 46 kg of material will be consumed for harvesting and transporting 1000 m3ub to the roadside. The corresponding figure for the high scenario is 58 kg. The total component mass expected to be replaced during the operational lifetime (18000 E15 hours) of the machines was also calculated. According to the low scenario 38- 45% of the mass of a machine will be changed during its operational lifetime. The corresponding figure for the high scenario is 50-56%.

Fuel consumption and GHG emissions of forest biomass supply chains in Northern Sweden: a comparison analysis between integrated and conventional supply chains

ABSTRACT Forest biomass can be used as source of renewable energy, contributing to mitigate climate change. Currently, forest biomass is one of the most important energy sources in Sweden, accounting for around 20% of the total supply. New demands of forest biomass may be expected due to the European Union energy targets, the previous high oil prices, the energy supply security, and the bioenergy market. However, the supply depends on the intensity of conventional final felling operations. Thus, it is crucial to determine the energy demands of conventional and new forest assortment supply chains and promote those with the highest energy efficiency and least greenhouse gas (GHG) emissions. An attributional life cycle assessment approach was used to evaluate the fuel consumption and GHG emissions associated with the combustion of fossil fuels used in forest operations, transportation and comminution of forest biomass procured via two kinds of supply chains in Northern Sweden: conventional and integrated. The results indicate that most fuel was consumed in transportation processes. The integrated supply chains (in which the harvesting of industrial roundwood is integrated with extraction of forest fuels) are more energy efficient than conventional supply chains, and have the potential to reduce GHG emissions by approximately 13%. Abbreviation: BWT: bundled whole small trees; CTL: Cut-to-length; ET: energy thinning; FF: final felling; FT: first thinning; FU: functional unit; GHG: greenhouse gas; GWP: global warming potential; LCA: life cycle assessment; LR: logging residues; LT: long tops; ODt: oven dry tonne; ORN: Örnsköldsvik (industrial location); PCT: pre-commercial thinning; PL: pulpwood; PM15h: Productive machine hours including delays shorter than 15 min; RS: Rough-delimbed tree sections; SC: stump core; SL: sawlogs; SP: stumps; ST: second thinning; STO: Storuman (industrial location); u.b: under bark; UME: Umeå (industrial location)

Integrated supply of stemwood and residual biomass to forest-based biorefineries

ABSTRACT The demand for forest biomass as raw material for a wide range of products in the developing bioeconomy is expected to increase. Along with a constant pressure on forestry to increase its productivity, this development has led to the search for new procurement methods and new assortments. The present study assessed innovative supply chain practices, with a particular focus on the integrated supply of stemwood and residual tree parts. The assortments considered included tree sections, long tops, saw logs with stump cores and small whole trees from thinnings. The assessment included geographically explicit modelling of the supply chain operations and estimation of supply cost and energy use for three industrial locations in Northern Sweden. The innovative supply chains were compared to conventional, separate, harvest of stemwood and logging residues. We conclude that integrated harvest of tops and branches with stemwood assortments, as well as whole-tree harvest in early thinnings, has a significant potential to reduce the supply cost for the non-stemwood assortments. Stump wood generally remains the most expensive assortment. The energy use analysis confirms earlier research showing that the energy input is relatively small compared to the energy content of the harvested feedstock. ABBREVIATIONS BWT, bundled whole trees; CTL, cut-to-length; ET, energy thinning; FF, final felling; FT, first thinning; LR, logging residues; LT long tops; ORN, Örnsköldsvik; PCT, pre-commercial thinning; PL, pulpwood; RS, roughly delimbed tree sections; SEK, Swedish currency; SFA, Swedish Forest Agency; SL, sawlogs; SNFI, Swedish National Forest Inventory; SP, stumps; SPC stump core; ST, second thinning; STO, Storuman; UME Umeå; WT, whole small trees;