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Polymers reinforced with virgin carbon fibers (VCF) are being used to make spar caps of wind turbine (WT) blades and polymers with glass fibers (GF) to make skins of the blade components. Here, we assess the life cycle environmental performance of the hybrid blades with spar caps based on VCF and the shells and shear webs based on RCF (recycled CF) composites (RCF-hybrid). The production of the WT blades and associated reinforced polymers is assumed to occur in Sweden, with their uses and end-of-life management in the European region. The functional unit is equivalent to three blades in an offshore WT with the market incumbent blades solely based on the GF composite or the hybrid option. The RCF-hybrid blades offer 12-89% better environmental performance in nine out of 10 impact categories and 6-26% better in six out of 10 impact categories. The RCF-hybrid blades exhibit optimum environmental performance when the VCF manufacturing facilities are equipped with pollution abatement systems including regenerative thermal oxidizers to reduce ammonia and hydrogen cyanide emissions; spar caps are made using VCF epoxy composites through pultrusion and resin infusion molding, and the blade scrap is mechanically recycled at the end of life. The energy and carbon payback times for the RCF-hybrid blades were found to be 5-13% lower than those of the market incumbents.

A number of factors affect the success, or otherwise, of any technological innovation. In this paper, we consider factors that affect the success of innovations in the context of forest machinery manufacturing (FMM). We report the results of a study that seeks to determine the relative importance of 19 different factors affecting the success of innovations in the FMM sector. The first stage of the study makes use of the analytic hierarchy process to determine the relative importance (weights) of these factors, based on the responses of 15 decision makers (DMs) employed by different FMM companies. The study then considers three different ways of weighting the responses of DMs, based on different assumptions about how the responses of outliers—those DMs whose views differ significantly from the majority—should be handled. The first method assumes that the responses of all DMs are of equal value. The second assumes that the influence of outliers' responses should be reduced and makes use of a Euclidean distance metric to determine the weight that should be ascribed to each DM's responses. The third assumes that the influence of outliers' responses should be increased and makes use of hierarchical clustering techniques. Although the weight assignment methods were based on very different assumptions about how to treat the views of outliers, they produced similar rankings of factors. Results showed that for FMM companies, customer satisfaction, proportion of total sales by new products, influence on the overall profit of the company, and growth of demand for the company products were the most important factors for measuring the success of innovations.

Long distance transportation of forest biomass is often unavoidable because the biomass is dispersed over large land areas. This is a problem that limits the development of biorefineries all over the world. The use of biomass terminals where forest biomass is transported to, stored, processed (mostly by mobile machinery), and reloaded can facilitate more environmentally friendly and efficient transportation to a biorefinery. The challenge is to identify the locations that should be selected for terminal establishment in order to minimize the cost of biomass procurement. In this study, locations for terminal establishment are proposed based on an optimization method (Combopt) that simultaneously minimizes the harvesting, transportation, and terminal costs for round wood and logging residues. The outcome of this method was compared with several other methods imitating situations with limited knowledge to estimate potential opportunity costs of potential knowledge deficiency when selecting terminal locations. The results of the Combopt method suggest that six terminals are required in order to minimize the overall cost of satisfying the estimated demand from the biorefineries. The opportunity cost of alternative terminal selection methods ranged from 3.1 to 35.4 million SEK (0.5-6.1% of total procurement cost). Methods that considered biomass relatively close to terminals had lower opportunity costs, together with methods minimizing transportation and terminal cost for the most common wood assortment. The methods and results could be applicable in other parts of the world were similar problems exists in forestry and other industries.

The European Union is accelerating its rollout of sustainable energy production and promotion of a circular economy. Electricity from biogas has synergy with energy-policy and rural-development goals yet its economic value is often convoluted. This study assessed the economic potential of biogas electricity using a representative rural case and quantified the cost and level of state support required for viability. The cost of CO2-equivalent emission reductions was determined using the recast Renewable Energy Directive (RED II). The results showed that a feed-in tariff of 0.33 € kWh−1 for green electricity was required for economic feasibility. This yielded a CO2 cutting cost of 251 € t−1. The methane energy potential was 78 467 kWh a−1 from 31 498 kg (dry mass) of substrates, 80% livestock manure and humanure and 20% plant-based. Circular use of the digestate from anaerobic digestion, enabled a nitrogen recovery potential of 1 575 kg a−1. The conclusions reached are that the economic value of the avoided emissions, through the RED II framework, is significant but it does not substantially improve the cost-effectiveness of biogas as an emission-mitigation technology. For biogas plant capacities less than 500 kW, current EU feed-in tariffs do not support economic viability.

Polymeric membranes are important in advanced separation technologies because of their high efficiency and low environmental impact. However, procedures for membrane production are far from sustainable and environmentally friendly. This work presents a life cycle assessment of the environmental impact of fabricating 1000 m2 of hollow fiber polymeric membranes. Membrane materials considered include the most popular fossil- and bio-based polymers in current use, i.e., polysulfones, polyvinylidene fluoride, and cellulose acetate. Solvents considered for use in polymer dope solution included polar aprotic solvents (N-Methyl-2-pyrrolidone, N, N-dimethylacetamide, and dimethylformamide) that are widely used in industry and an alternative green solvent (ethylene carbonate). The impacts of membrane production on global warming, marine ecotoxicity, human carcinogenic and non-carcinogenic toxicity, land use potential, and fossil resource scarcity were analyzed. Additionally, the impact on the sustainability and environmental cost of membrane production resulting from replacing fossil-based polymers with bio-based polymers or substituting toxic solvents with a green alternative was investigated. Hot spots in the membrane production process were identified, and measures to reduce the environmental impact of membrane production were proposed.

The oil scarcity and the rise in earth temperature have elevated the interest in lignocellulosic biorefineries. Lignin has high potential to be used in various applications including the production of biomaterials and transportation fuels. Among the different sources of lignin, organosolv lignin has the advantage of being sulphur-free and of low ash content compared to other types of industrial lignin. The present study focuses on cradle-to-gate life cycle and cost assessment of a novel organosolv lignin production process from spruce bark. The system boundary included production of tannin, lignin from spruce bark and handling of waste including all the inputs (material and energy) and outputs (emissions) in the process. Baseline scenario and scenarios S1 and S2 were compared to identify the most environmentally and economically suitable scenario. The baseline scenario is lignin production with co-production of tannin and tannin free bark (TFB) from spruce bark; scenario S1 is lignin production from TFB; and scenario S2 is lignin production from TFB with mass allocation. The functional unit was 1 kg lignin produced and ReCiPe 2016 Midpoint (H) method was used for the environmental impact assessment. The results showed that the baseline scenario had higher global warming potential (GWP) (2.14 kg CO(2)eq.) and total cost (1.959 (sic)/kg) than S1 (1.39 kg CO2 eq. and 1.377 (sic)/kg respectively) and S2 (0.23 kg CO(2)eq. and 0.998 (sic)/kg respectively) scenarios. The results of sensitivity analysis showed that the use of bioethanol instead of ethanol reduced the burden on GWP but increased the burden on the land use impact category. (C) 2020 The Author(s). Published by Elsevier Ltd.

The objective of this study was to establish a Geographical Information System (GIS) based methodology to analyze the viability and optimal location of a new hypothetical wood-fired power plant in a specific region. The available woodfuel of Eucalyptus globulus suitable for energy use was calculated based on a WISDOM database (Woodfuel Integrated Supply/Demand Overview Mapping) which takes into account physical and legal accessibility of the resource. Available woodfuel is defined as the material remaining on the ground (crown and bark) after harvesting Eucalyptus stems, discounting the volume required to meet the current energy demand. Various spatial analyses were performed using ArcGIS 10.2.1, particularly the Network Analyst tool, to identify the optimized location of the new power plant. Then, considering the most common biomass harvesting system in a specified region, the costs and GHG emissions of the supply chain for this demand point were calculated. Total costs were calculated using machine productivity data and minimized distance calculation and GHG emissions by the amount of CO 2 e emitted, based on the Life Cycle Analysis methodology using productivity and fuel consumption data. A sensitivity analysis was also carried out to test the influence of moisture content and transport distances on the total cost and the GHG emissions. The results show that bundling was the highest cost (63.67% of total costs), followed by trucking (26.80%) and forwarding (9.53%). The GHG emissions for the whole system were 9.17 Kg CO 2 e/MWh, with the trucking being the greatest contributor, and bundling the second. The energy balance ratio (energy required as a percentage of energy produced by the system) was slightly over 2%, demonstrating high efficiency. The methodology presented here will help policy makers to evaluate possible locations for any future wood-fired power plants in terms of the lowest economic costs of supplying woodfuel and its environmental impact. This study extends on the scope of prior research, providing a realistic and detailed methodology for planning and logistics decision making in relation to the dynamization and sustainability of woodfuel for energy use.

There is a variety of different methods for carrying out sustainability impact assessments of energy value chains. The different methods can use the same, or similarly named, indicators, but the methods make different assumptions about the system boundaries and differ in the purpose of the assessment, and this can lead to confusion when communicating the results of different studies. A method expansion of Sustainability Impact Assessment (SIA) was developed and tested to allow comparison of environmental indicators of energy use and generation, energy balance and greenhouse gas emission as calculated according to three different methods: (1) direct value chain environmental impacts (referred to as SIA in this paper), (2) direct plus indirect impacts following a Life Cycle Assessment (LCA) approach, and (3) a method based on European Sustainability Criteria (ESC) for solid biomass. The Tool for Sustainability Impact Assessment (ToSIA 2.0) was used for this method expansion. Indicator values followi...

Increasing demand for biofuel production and global competition for the use of natural resources are key factors in finding new and environmentally safe routes for methanol production. In the present study, life cycle assessment was used to analyse the potential environmental impact and environmental cost of a novel methanol production process from wood compared to a conventional processes. Both the novel and the conventional process were divided into three stages: pre-treatment, gasification, and syngas cleaning and methanol synthesis. The environmental impacts were assessed and compared using Simapro 9 (ecoinvent 3.5 database) and the ReCiPe 2016 (World-H) midpoint method. The results, expressed per tonne methanol, showed that the impact categories of global warming potential (GWP) and marine ecotoxicity potential were lower in the novel process in comparison to the conventional process (48.2 kg CO

Renewable energy production from biomass sources and related bio-based economy is gaining more and more attention nowadays. Research related to biomass and bio-based fuels is an important part of the strategic agenda of many countries in Europe and Asia. Furthermore, upscaling investigation in the area is undergoing in many other countries around the globe like United States, China, and India. The expansion of the biofuels usage raises concerns related to their production sustainability, including several environmental, economic, and social aspects. The aim of this chapter is to present in detail the evaluation of different climate matrices used in global biomass energy research. A strategic framework for production of biofuels and their utilization is also presented. This strategic framework merges the different environmental indicators and conversion technologies in order to achieve a sustainable circular bio-based economy.

Establishment of biorefineries for processing forest biomass in the Nordic region is extremely costly due to the high investment, running, and procurement costs. Procurement costs could be reduced by allowing all actors to open access to all available terminals in an area (regardless of ownership) and allowing trucks with higher gross weight. These impacts of changes were evaluated for deliveries of logging residue and energy wood chips to a potential biorefinery, from two suppliers in northern Sweden. Open access to all terminals reduced the terminal-procurement costs by 2-6% and the terminal-to-biorefinery transportation costs by 7-9%. When 74 tonnes trucks were used instead of 60 tonnes, the terminal-to-biorefinery transportation costs were reduced by 4 and 3%, in the current situation and with open access to terminals, respectively. However, the largest effect of open access was that the fraction of short-distance transportation to terminals and train transportation from terminals increased significantly. This indicated that open access to terminals and relatively heavy trucks between terminals and the biorefinery are preferable from both environmental and economic perspectives. Furthermore, the estimated cost saving was adequate and should allow the deliverers to pay a reasonable fee for the use of terminal space.

Over 640 million people in Africa are expected to rely on solid-fuels for cooking by 2040. In Western Kenya, cooking inefficiently persists as a major cause of burden of disease due to household air pollution. Efficient biomass cooking is a local-based renewable energy solution to address this issue. The Life-Cycle Assessment tool Simapro 8.5 is applied for analyzing the environmental impact of four biomass cooking strategies for the Kisumu County, with analysis based on a previous energy modelling study, and literature and background data from the Ecoinvent and Agrifootprint databases applied to the region. A Business-As-Usual scenario (BAU) considers the trends in energy use until 2035. Transition scenarios to Improved Cookstoves (ICS), Pellet-fired Gasifier Stoves (PGS) and Biogas Stoves (BGS) consider the transition to wood-logs, biomass pellets and biogas, respectively. An Integrated (INT) scenario evaluates a mix of the ICS, PGS and BGS. In the BGS, the available biomass waste is sufficient to be upcycled and fulfill cooking demands by 2035. This scenario has the lowest impact on all impact categories analyzed followed by the PGS and INT. Further work should address a detailed socio-economic analysis of the analyzed scenarios.

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...

This study took a Life Cycle Assessment (LCA) perspective to model a total of twenty forest supply chains, from seedling production to forest biomass delivery to industry. Four scenarios were analyzed, two in Sweden and two in Canada. Resource and energy consumption, and emissions to air, water and soil of conventional and biomass dedicated supply chains were evaluated and compared. The Swedish supply chains showed a better environmental profile, on average, per oven dry tonne (ODt) than the Canadian ones in the regions studied. In terms of climate change potential the Swedish biomass dedicated supply chains generated 48.8 kg CO2-eq, 13%, 30% and 38% lower than Swedish conventional, Canadian biomass dedicated and Canadian conventional supply chains, respectively. Sawlogs from final felling in the Swedish biomass dedicated supply chains generated 34.2 kg CO2-eq, the lowest emissions within the roundwood assortments. Concerning the forest fuel assortments in form of wood chips, pulpwood from final felling in the Swedish conventional supply chains, and stump core and long tops from final felling in the Swedish biomass dedicated supply chains generated the lowest emissions: 48.9 kg CO2-eq, 52.3 Kg CO2-eq and 57.8 kg CO2-eq respectively. Transport from forest to industry, harvesting, extraction, chipping, and crushing were identified as hotspots in the forest supply chains. Forwarding versus skidding, chipping and transportation were the processes that differed the most between countries. In both countries, when the supply chains were biomass dedicated the environmental impacts per ODt were lower than in the conventional supply chains. Therefore, integrating forest fuel supply with industrial wood harvesting has the potential to reduce emissions.

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.ABBREVIATIONSBWT, 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

In order to achieve a net zero emission economy by 2045, Sweden’s inland biomass resources are under examination. Large amounts of forest biomass in the north of the country are not utilised. In this study, resource mapping of surplus forest biomass, (logging residues, tree stumps and mill by-products) is carried out according to ecological harvesting restrictions to determine the annual potential of this resource. Using a network of terminals, optimised supply chains are used to determine the cost of feedstock supply and upgrading of biomass to value-added torrefied pellets. The results indicate that the total biomass surplus is 5.75 Mt (dry mass), representing a forested procurement area half the size of Sweden (224 500 km2). The surplus represents two per cent of Sweden’s annual energy consumption and 60 % of its coal and coke use. Aggregation of the existing terminal network results in 274 to 1611 kt of biomass (dry mass) supplied to ten terminals. Supply and upgrading costs at the terminals reflect a trade-off between the size of procurement area and the scale of upgrading; a large plant capacity corresponds to a low upgrading cost but a large supply cost and vice versa. The lowest supply cost is 79 € t−1 (dry mass) of feedstock and the upgrading capacity ranges from 86 to 1310 kt (dry mass). Utilisation of the surplus would require an effective energy cost range of 27–37 € MWh−1 exclusive of delivery cost to the end user and operational profits – corresponding to a minimum torrefied pellet price of 131 € t−1. Though much higher than other solid fuels, the energy price is comparable to that of natural gas. The results of this study have importance for legislation supporting EU and Swedish energy policy objectives.

Purpose of Review One of the challenges of forest operations is to consider the consequences of different management strategies and to estimate the economic, environmental and social performance of different processes, products, or services. From the methods available to quantify the impact of alternative forest management, we selected the method of Sustainability Impact Assessment (SIA), an iterative process that includes the analysis of the societal, environmental, and economic sustainability pillars and offers a wider assessment framework, which is useful for stakeholders and policy makers. The purpose of this review is to identify the state of the art and trends of SIA in forest operations. Recent Findings There are few studies including all pillars of sustainability and most of the studies consider different aspects of environmental or economic impacts. It is important to determine the system boundaries and select the appropriate indicators in order to have a comprehensive SIA. Different harvesting technologies and their deployment can influence costs, productivity, environment, and safety risk. Some indicators, such as cost and productivity, can vary between countries and different scenarios. Summary Efficient machines, appropriate technical systems, innovative products, and up-to date training of operators can have a positive impact on sustainability. Economic factors can change at a rapid pace, and new machines can play a positive role in forest operations (e.g., lower fuel consumption, higher level of safety and comfort for operators). The inclusion of indicators measuring the extra value of the forest should be considered. We suggest adopting sensitivity analysis during the assessment of key processes to observe the effect on the hot spots.

The geographic locations of biofuel production facilities should be strategically chosen in order to minimise the total cost of using biofuels. Proximity to biomass resources, possibilities for integration, and distance to biofuel users are aspects that need to be considered. In this paper, the geographically explicit optimisation model BeWhere Sweden was used to investigate the future production of next-generation biofuels from forest biomass in Sweden. A focus was placed on the integration of biofuel production with the existing forest industry, as well as on how different parameters affect biofuel production costs, the choice of technologies and biofuels, and the localisation of new biofuel plants. Six examples of different biofuel routes were considered. A methodology was developed considering detailed, site-specific conditions for potential host industries. The results show that the cost of biomass and the biofuel plant capital cost generally dominate the biofuel cost, but the cost for biomass transportation and biofuel distribution can also have a significant impact. DME produced via black liquor gasification (naturally integrated with chemical pulp mills) and SNG produced via solid biomass gasification (mainly integrated with sawmills), dominate the solutions. The distribution of these technology cases varies depending on a number of parameters, including criteria for sizing biofuel plants, the electricity price, the biofuel distribution cost and the cost of biomass, and is sensitive to changes in these parameters. Generally, plants with low specific investment costs (i.e., high biofuel production) and/or plants with low specific biomass transportation costs occur most frequently in the solutions. Because these properties often vary significantly among biofuel production facilities at different host industry sites of the same type, the results show the advantage of including site-specific data in this type of model. (C) 2015 Elsevier Ltd. All rights reserved.

As there is increasing interest in the use of biomass for energy in Sweden, the potential availability and harvesting costs of forest roundwood, harvesting residues and stumps were estimated up to the year 2069 in 10-year intervals, using a high spatial resolution GIS. In each individual forest area, an average harvesting cost per forest assortment was estimated, based on the geographic and other properties of the area. Using cost structure and resource availability, marginal cost curves were constructed to allow analyses of the effects of changing market conditions and different policy frameworks. Based on geographically explicit data, the results indicated that the average harvesting costs would be 21–24 € m −3 for roundwood, depending on the type of harvesting and extraction operation. The corresponding cost estimate for harvesting residues was 23–25 € m −3 and 35 € m −3 for stumps. The harvesting cost estimates lie on the steeper part of the marginal cost curve, suggesting that increases in the supply of woody biomass can only occur at significantly higher harvesting costs. From a policy perspective, this suggests that subsidies aimed at reducing the harvesting costs will only have limited success in increasing the harvested volumes, given current technology. Therefore, for future development in the supply of forest assortments for energy generation, it is important to consider not only the supply potential, but also the integration of improvements in harvesting and transportation systems.

This paper presents the development and demonstration of an approach for incorporating decisionsconcerning forest management within the framework of a TIMES energy system model. The presented model explicitly incorporates a number of long-term applicable forest harvest trajectories, thereby endogenously linking decisions concerning harvest levels with the development of the energy system. The operation of the model is demonstrated by evaluating the optimal long-term harvesting level of Swedish forests for the development of the bioenergy and forest industry sectors. The experimental results suggest that in the short term (between 2010 and 2035), an increased national forest harvest level would be benecial for the joint development of the two sectors. Such a short-term increase in harvest levels of forest biomass sources would ensure an adequate and reliable supply of biomass sources for the expansion of the two sectors. However, in the long term (between 2070 and 2100),the endogenously computed forest harvest level stabilized at a reference harvest level corresponding to a continuation of the current trend in forest harvest levels. While the emphasis of this paper is on the methodological development of the model, the experimental results highlights the importance of considering cross-sectorial implications when assessing the future developments of the bioenergy and forest industrial sectors. This paper presents the development and demonstration of an approach for incorporating decisions

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.

First and second generation biofuels are among few low-carbon alternatives for road transport that currently are commercially available or in an early commercialization phase. They are thus potential options for meeting climate targets in the medium term. For the case of Sweden, we investigate cost-efficient use of biofuels in road transport under system-wide CO2 reduction targets to 2050, and the effects of implementation of targets for an almost fossil-free road transport sector to 2030. We apply the bottom-up, optimization MARKAL_Sweden model, which covers the entire Swedish energy system including the transport sector. For CO2 reductions of 80% to 2050 in the Swedish energy system as a whole, the results of the main scenario show an annual growth rate for road transport biofuels of about 6% from 2010 to 2050, with biofuels accounting for 78% of road transport final energy use in 2050. The preferred biofuel choices are methanol and biomethane. When introducing additional fossil fuel phase-out policies in road transport (−80% to 2030), a doubling of the growth rate to 2030 is required and system CO2 abatement costs increases by 6% for the main scenario. Results imply that second generation biofuels, along with energy-efficient vehicle technologies such as plug-in hybrids, can be an important part of optimized system solutions meeting stringent medium-term climate targets.

Stump wood is a possible source of renewable energy, but before its potential as a fuel can be utilised to a high degree, new harvesting techniques should be developed to reduce the environmental impact (notably ground disturbance) of harvesting stumps. The forces required to lift and drag stumps out of the soil are known. In this study, two unknown and important parameters were addressed: the torque required to uproot stumps by twisting them and the torque required to cut lateral roots around stumps. A new, improved stump-twisting rig was designed and used in trials with 28 Scots pine (Pinus sylvestris) trees (breast-height diameter over bark, 153–427 mm). The measured torque requirements ranged from 10 to 50 kNm. Twisting stumps required more torque than cutting lateral roots around stumps and the required torque increased with increases in stump size. The results indicate that a wrist on a big feller-buncher, but not a conventional rotator used on forest machines, should be able to generate sufficient torque to cut the roots around stumps such as those used in this study.

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.

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 vehicle’s heading and position. A gyro was used to compensate for the influence of the vehicle’s 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 satis-factorily 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.

A saw-bar with a saw-chain is a common tool in both mechanized and motor-manual harvesting operations. The friction between the saw-bar and the saw-chain must be reduced by lubrication. A precise oil flow control can reduce the amount of oil needed. Traditionally, mineral oils have been used, but the use of biodegradable vegetable-based oils has increased. The goal of this study was to evaluate the lubrication characteristics at different oil flows of two vegetable-based and one mineral-based saw-chain oil. The study was done on an experimental rig with a saw-chain speed of 23 m/s and with pressure between the saw-chain and a rotating rubber roller. The temperature of the saw-bar was used as an indicator of the lubrication efficiency. The saw-chain tension was constant and independent of temperature. In general, increased oil flow resulted in a lower temperature. For rapeseed oil and pine oils, the results were consistently significant between oil flows of 2 and 6 ml/min. At an oil flow of 2 ml/min and 5 minute test time, pine oil resulted in the highest temperature (121°C, standard deviation [SD] 6.4) and at 6 ml/min the lowest temperature (99°C, SD 1.1) compared with the other oils. No difference in temperature was found between mineral oil and rapeseed oils at oil flows of 2 or 6 ml/min. An oil flow of 2 ml/min was found to be enough to prevent high temperatures for all oil types. The study method, with an adjustable experimental rig as the tool, was found to be suitable for studies on lubrication of the saw-bar and saw-chain.

Forwarder fuel consumption was studied by examining a total of 27 forwarders under field conditions. Three datasets, representing different data acquisition methods, were used. In a field study, time and fuel consumption by work-element of two 20–21 tonne forwarders in final felling were recorded. In a questionnaire survey, daily data concerning fuel consumption, productivity and average extraction distance was provided on 18 forwarders, divided between final felling and thinning. Finally, accounting data on fuel consumption for 11 forwarders were obtained. In the field study, the fuel consumption varied between 8.3 to 15.7 l/PMH (productive machine hour) for different work elements. The total fuel consumption was 0.28–0.36 l/m3sub (solid under bark) at average extraction distances on 360–412 m for loads of sawlogs and 0.43–0.66 l/m3sub (458–514 m) for loads of pulpwood. 61–62% of that fuel was consumed during loading and driving during loading. The forwarders consumed 0.23–0.38 l/100 m driving a...

Understanding the characteristics of unutilized biomass resources, such as small-diameter trees from biomass-dense thinning forests (BDTF) (non-commercially-thinned forests), can provide important information for developing a bio-based economy. The aim of this study was to describe the areal distribution, characteristics (biomass of growing stock, tree height, etc.) and harvesting potential of BDTF in Sweden. A national forest inventory plot dataset was imported into a geographical information system and plots containing BDTF were selected by applying increasingly stringent constraints. Results show that, depending on the constraints applied, BDTF covers 9–44% (2.1–9.8 M ha) of the productive forest land area, and contains 7–34% of the total growing stock (119–564 M OD t), with an average biomass density of 57 OD t ha. Of the total BDTF area, 65% is located in northern Sweden and 2% corresponds to set-aside farmlands. Comparisons with a study from 2008 indicate that BDTF area has increased by at least 4% (about 102 000 ha), in line with general trends for Sweden and Europe. Analyses revealed that the technical harvesting potential of delimbed stemwood (over bark, including tops) from BDTF ranges from 3.0 to 6.1 M OD t yr (7.5 to 15.1 M myr), while the potential of whole-tree harvesting ranges from 4.3 to 8.7 M OD t yr (10.2 to 20.6 M myr) depending on the scenario considered. However, further technological developments of the harvest and supply systems are needed to utilize the full potential of BDTF.–1–13 –1–13 –1

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 forwarder's 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.

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.

International audience; The objective of this study is to improve evaluations of the future use of biomass sources in Sweden and France by representing the high spatial variations of the supply and cost of biomass sources in energy system models. The proposed methodology considers a high spatial disaggregation of biomass supply sources, as well as detailed biomass cost-supply curves, and is thereby able to account for spatial differences in heterogeneous land qualities, management strategies, and possible adaptation rates. Integrating the methodology into national or regional energy system models will enhance cost-effective evaluations of biomass sources as well as the development of the bioenergy sector. A TIMES energy system model was used to evaluate bioenergy production potential for France and Sweden based on domestic biomass sources and under the assumption that bioenergy production should not be at the expense of domestic food and forestry supply. Results show that by 2050, the biomass sources considered could provide as much as 250PJ of bioenergy in Sweden, and 1470PJ of bioenergy in France. Results further showed that 1st generation biofuels are likely to continue to play a substantial role in the biofuel mix. While 2nd generation biofuel production in Sweden is likely to be low, larger amounts of 2nd generation biofuels could be produced in France. However, the amount and type of 2nd generation biofuel produced in France was found to be highly dependent on the bioenergy demand level.

Increasing use of woody fuels requires that nontraditional types of raw materials are exploited, including logging residues and small-diameter trees. Although medium-scale combustors often use pellets, they could conceivably use dried chips of sufficiently narrow size distribution (henceforth pellet chips). The influence of the following factors on the relative cost-effectiveness of producing pellets and pellet chips was investigated for three plant sites in northern Sweden: (1) harvesting and transporting of forest residues; (2) the potential of existing energy plants to supply drying heat in periods of capacity surplus; (3) the distance to potential end-users. Data from the national forest inventory were used to estimate raw material costs. The resulting production costs were 144–176 $ per oven-dry tonnes (OD t) for pellets (27.4–33.5 $ MWh−1) and 143–173 $ OD t−1(27.2–33.0 $ MWh−1) for pellet chips, with harvesting, forwarding, chipping, and transporting of logging residues to the sites amounting to 114–122 $ OD t−1(21.7–23.2 $ MWh−1) for both fuels. Even though the differences in production costs were minor, the production of pellet chips requires significantly less electricity input per OD t of produced fuel. For cost reductions improved methods for wood fuel procurement, compacting and transporting of chips, small-scale low-temperature drying and foliage and bark separation are needed.

Stumpwood attracts renewed interest due to increased use of forest biomass for bioenergy. In Nordic countries stumps are generally uprooted with crawler excavators, which have strong cranes (ca. 400 kNm gross lift torque), but are not designed for moving in forest terrain. Their use is based on practical experience with available and tested machine types rather than thorough examinations of requirements, partly due to limited knowledge of force requirements for uprooting of stumps. Therefore, in this work mean and maximum forces required to vertically uproot stumps of Norway spruce (Picea abies) and birch (Betula spp.) were quantified together with the effects of various soil types and uprooting methods. The used excavator’s crane-mounted uprooting device enabled comparisons between usage of solely crane force, and a method in which preparatory loosening forces were applied prior to crane force. Uprooting stumps in single pieces proved difficult; 61% split unintentionally. Force requirements were similar across tree species, increasing curve-linearly with stump diameter, and stumps uprooted in a single piece required more force than split stumps. Preparatory loosening reduced crane force requirements and, surprisingly, less force was required to uproot stumps from a mesic, till soil than from a moist, finer-textured soil. No stump required more than 60 kN crane force and functions for maximum force requirements indicate that powerful harvesters and forwarders (gross crane lifting capacity of 273 and 155 kNm, respectively) should be able to uproot all stumps with ≤ 61 cm and ≤ 32 cm diameter, respectively, in one piece. Larger stumps could be managed if it is acceptable that stumps are split before uprooting.

Sustainably managed forests provide renewable raw material that can be used for primary/secondary conversion products and as biomass for energy generation. The potentially available amounts of timber, which are still lower than annual increments, have been published earlier. Access to this timber can be challenging for small-dimensioned assortments; however, technologically improved value chains can make them accessible while fulfilling economic and environment criteria. This paper evaluates the economic, environmental and social sustainability impacts of making the potentially available timber available with current and technologically improved value chains. This paper focuses on increasing the biomass feedstock supply for energy generation. Quantified impact assessments show which improvements – in terms of costs, employment, fuel and energy use, and reduced greenhouse gas emissions – can be expected if better mechanized machines are provided. Using three different methods – Sustainability Impacts Assessment (SIA), Life Cycle Assessment (LCA), and Emission Saving Criteria (ESC) – we calculated current and innovative machine solutions in terms of fuel use, energy use, and greenhouse gas emissions, to quantify the impact of the technology choice and also the effect of the choice of assessment method. Absolute stand-alone values can be misleading in analyses, and the use of different impact calculation approaches in parallel is clarifying the limits of using LCA-based approaches. The ESC has been discussed for the recast of the Renewable Energy Directive. Potential EU-wide results are presented.