| 1. |
- Anerud, Erik
(författare)
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An alternative supply system for stump biomass - coarse grinding combined with sieving of the produced hog fuel
- 2016
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 27, s. 109-114
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Tidskriftsartikel (refereegranskat)abstract
- Transport costs are one of the major costs in the supply chain of stumps for fuel. Stump parts are bulkyand it is impossible to achieve full tonnages on trucks and trailers even though the load space iscompletely full. The transport economy for stumps is also negatively affected by the large amount ofcontaminants in the loads. Grinding the stumps at the landing and sieving of the produced hog fuel hasthe potential to increase load weights and reduce both the amount of contaminants and the transportcosts. To evaluate such a system a series of studies were made. Results show that coarse grinding andsieving reduced both moisture and ash content in the produced fuel, thus increasing the heating valueper ton delivered fuel and transforming a soil contaminated material to an acceptable fuel. Transportpayloads increased substantially compared to transports of stump parts, but a transport distance of110 km was needed before the coarse grinding system provided lower cost than the standard systemwith transports of stump parts and grinding at the heating plant. Further studies are needed to evaluatethe total energy efficiency in the two systems. Coarse grinding and sieving is a feasible way to increasefuel quality and improve transport economy. However, total costs will in most cases be higher than forthe loose stump system which renders the method preferable only in cases where the sieving processconverts a non-acceptable material into an acceptable fuel.
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| 2. |
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| 3. |
- Anerud, Erik
(författare)
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Productivity and costs of sieving logging residue chips
- 2021
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 33, s. 80-86
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Tidskriftsartikel (refereegranskat)abstract
- Sieving of chipped forest fuels has recently been suggested as a way to reduce dry matter losses during storage. Sieving provides a more homogeneous acceptable material with better storage properties, which reduces the risk of energy and dry matter losses and spontaneous ignition. Screened chips can be priced higher due to better quality, and both acceptable and reject fractions are more homogeneous, which improves combustion control. Sieving is costly and the reject fraction is not suitable for storage. Five sieving operations were studied, three involving vibrating screens and two involving starscreens. On average, starscreens were more productive than vibrating screens. In all operations, the sieving machine limited productivity, and the loader feeding the machine was not fully utilized. Sieving costs were under two euro per MWh of chips, which may be recovered through higher values and lower storage losses in the acceptable fraction. If sieving operations were used to increase storage of chips, it could increase the annual utilization of chippers and chip trucks in the supply chain, thereby reducing supply costs. Profitable sieving operations require demand for the fine fraction at a price close to that of residue chips.
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| 4. |
- Athanassiadis, Dimitris
(författare)
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Sustainability impacts of increased forest biomass feedstock supply - a comparative assessment of technological solutions
- 2018
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 29, s. 99-116
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Athanassiadis, Dimitris
(författare)
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Threefold sustainability impact assessment method comparison for renewable energy value chains
- 2017
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 28, s. 116-122
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Tidskriftsartikel (refereegranskat)abstract
- 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 following the three different approaches were calculated for a typical Nordic bioenergy harvesting chain producing forest wood chips. The indicator values for SIA, LCA and ESC are made comparable side by side, and give thus more insight on the difference and purpose of the three different methods when applied to the same harvesting chain.
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| 6. |
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| 7. |
- Berg, Simon, et al.
(författare)
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Opportunity cost of several methods for determining forest biomass terminal locations in Northern Sweden
- 2020
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 31, s. 37-50
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Berg, Simon, et al.
(författare)
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Simulating conventional and integrated stump- and round-wood harvesting systems: a comparison of productivity and costs
- 2014
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 25, s. 138-155
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Tidskriftsartikel (refereegranskat)abstract
- Tree stumps could make a signi reliance on fossil fuels. However, ground disturbance due to stump harvesting can be an unintended negative environmental consequence. Harvesting only the central part of the stump can reduce ground disturbance, but this is not pro harvesting of stump-center and round-wood in a single operation. We compare an integrated system for such simultaneous harvesting of stems and stump-centers with a conventional system harvesting stem and stump separately. The conventional system used a harvester, a forwarder, a stump harvester and a stump forwarder, while the integrated system used a feller-puller that fells the trees with the stump center attached, an in-stand processor, and a forwarder. The work of the machines was simulated using discrete-event simulation and the costs of the two machine systems were compared. The integrated system produced only 12 volume produced by the conventional system. The integrated system produced stump-wood at a lower cost than the conventional system for larger trees (>420 mm breast-height diameter). For smaller trees, it was not possible to determine which was the more economical system. Further empirical data are required to resolve the issue, for instance concerning the time required to cut or break the roots around a tree.ficant contribution as a renewable energy source in the transition away fromfitable with the machinery and systems currently used. One possible solution is to integrate the–33% of the stumpwood
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| 9. |
- Bergström, Dan, et al.
(författare)
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Effects of boom-corridor thinning on harvester productivity and residual stand structure
- 2022
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 33, s. 226-242
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Tidskriftsartikel (refereegranskat)abstract
- Biomass derived from small-diameter, dense, thinning stands is largely underutilized within the European Union, mainly because of in-effective harvesting methods and cutting technology, leading to high supply costs. Therefore, the efficacy of boom-corridor thinning (BCT) and selective thinning (ST) on harvester felling and bunching productivity was compared for the first thinning of whole tree biomass in small-diameter, dense stands. BCT working method is when trees are cut with linear movements of the harvester's boom reach, along narrow corridors, instead of cutting each tree selectively (ST). Trials were performed in six forest stands, one in Sweden, two in Finland, and three in Slovenia, using the same harvester and operator. A time-and-motion study was carried out in 64 pre-marked study units (32 replications per method), across a variety of stand conditions. The biomass removal for both treatments averaged 40.2 dry t ha -1 and BCT productivity averaged 5.4 dry t PMh -1. For BCT, harvester work time consumption (sec tree -1) and productivity (dry t PMh -1) were on average 27% lower and 16% higher, respectively, compared with ST. The effectiveness of the accumulating felling head technology used could potentially be increased by implementing a feed-roller system when handling excessive tree lengths. Developing dedicated harvesting technology for BCT could further boost productivity, facilitating cost-effective and sustainable utilization of low-value small-diameter tree biomass and replacing fossil resources.
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| 10. |
- Bergström, Dan, et al.
(författare)
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Evaluation of a novel prototype harvester head in early fuel-wood thinnings
- 2014
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Ingår i: International Journal of Forest Engineering. - : Informa UK Limited. - 1494-2119 .- 1913-2220. ; 25, s. 156-170
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of this study were to evaluate and compare the productivity and operating costs of two harvesting systems for fuel-wood production in dense early thinnings, from stand to road-side: a harvester prototype MAMA (brand name) felling head featuring a feed-roller system for compression-processing paired with a standard forwarder; and a harvester with a conventional C16 felling head paired with a forwarder having a grapple-saw for bucking. Because the MAMA head was a prototype, an additional objective was to identify factors that in compression-processing and bunching of whole tree-parts using the MAMA head was no greater than that for the felling and bunching of whole trees with the C16 head. The feed-roller system increased the ef bucking process and also increased the bulk density of the harvested bunches by 47 the overall harvesting yield by 10 12 size by 17 12% for an extraction distance of 300 m (one way). Given typical stand conditions and an extraction distance of 300 m, the operating costs of the system with the MAMA head were 1% higher than for the C16 head. In addition, the operating costs of the MAMA system should decrease with the extraction distance. In conclusion, even though the MAMA head is an early prototype that has not been heavily optimized in terms of mass and functionality, its operating costs are already comparable to those of conventional alternatives. With further development, it could signifitted with afluenced the effectiveness of the MAMA system. The time required for the felling, accumulation,ficiency of the–70%. However, it reduced–23%. Consequently, the harvester productivity with the MAMA head was–14% lower than with the C16 head. However, because the MAMA head also increased the forwarder’s load–24% through its compression-processing of the biomass, it increased the forwarder’s productivity byficantly reduce the operating costs of harvesting from stand to road-side.
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