Browsing by Subject "hakkuutähde"
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(2016)This study is part of the joint research program of Sustainable Bioenergy Solutions for Tomorrow (BEST) by Natural Resource Institute Finland. This is the first study to examine and analyze the fast track supply chain for harvesting residues. The fast track supply chain is based on roadside chipping of logging residues, in which chips from final felling harvested during spring, summer and autumn are transported straight to the power plant with maximum of half month roadside storing. The aim of this study was to evaluate the cost effects of fast track supply chain. In addition, the factors affecting to the unit costs were investigated. Activity-based costing was used as a study method for analyzing the supply alternatives of logging residues. Data for this study was acquired from a large-scale industrial company purchasing forest biomass. Data consisted roadside storage locations and volumes (solid-m3) of logging residues from Norway spruce dominated final fellings. All activities were identified and costs were calculated in each supply method. Supply costs were presented in euros per megawatt hour were also compared to the total received energy. According to the results supply costs of fast track method was smaller than the costs of the conventional supply method. On average fast track supply costs were 7.1–13.3 % smaller than conventional supply method. Storing cost, including dry matter loss and capital cost, was the most significant factor for influencing differences in total supply cost. Cost of dry matter loss was 5.3–11.5 % higher in conventional supply method than in fast track supply method. In addition, capital costs were 0.4–1.9 % bigger in traditional procurement. Procurement costs of logging residue supply for energy-use can be decreased by using fast track supply chain. Although results proved that fast track supply chain decreases total procurement costs, one should remember that the volume of logging residues must be fitted to power plant’s energy demand.
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(2019)Nitrogen (N) availability often limits plant growth in the boreal forest ecosystem. There has been a lack of reliable method to study soil N supply as in traditionally used potassium chloride (KCl) extraction sampling and sample preparation disturb soil structure and stimulate N mineralization, leading to the overestimation of inorganic N forms ammonium (NH4+) and nitrate (NO3-) and underestimation of organic N forms such as amino acids. Diffusion-based microdialysis technique for the sampling of soil diffusive N fluxes gives an opportunity to study soil N supply at a scale that is relevant for plant N uptake, as microdialysis probe has a membrane that reminds the plant fine root in its scale and also, to some extent, in its function. During sampling, the movement of water inside the microdialysis probe induces diffusive flux of solutes across the membrane surface along the concentration gradient. The aim of this study was to test the performance of microdialysis technique at different soil moisture content levels and its capability to monitor temporal changes in diffusive N fluxes in laboratory experiments (ex situ). Soil fine-scale N dynamics were further studied by comparing the diffusive N fluxes in the field (in situ) in boreal forest soil to multiple factors that are thought to affect forest soil N availability. In this study, soil diffusive NH4+, NO3- and amino acid N fluxes were sampled ex situ from sieved soils taken from three different sites – clear-cut, spruce stand (MT spruce) and pine stand (VT pine) in Lapinjärvi, Finland in November 2017. In ex situ microdialysis experiments, the diffusive N fluxes were observed at three different soil moisture content levels and after N addition. In situ microdialysis sampling was run at the logging residue experiment of the Lapinjärvi clear-cut site and at the MT spruce site in June 2018 and at the pine logging residue experiment in Kiikala, Finland in September 2018. The results from the in situ microdialysis were compared with soil moisture content, pH, C-to-N ratio and temperature as well as with the net N mineralization and net nitrification rates, microbial biomass C and N contents and the concentrations of volatile monoterpenes and condensed tannins, factors that are assumed to affect N availability in forest soil. Nitrogen fluxes sampled ex situ showed that the total amino acid flux in the soil taken from the clear-cut site was only half of that in the MT spruce soil whereas NO3- flux was two times higher at the clear-cut site than at the MT spruce site. MT spruce soil with a moisture content of 60 % water-holding capacity (WHC) had significantly higher NH4+ flux than the same soil in its field moisture content (44 % WHC). Nitrogen pulse was detected in all soil samples as increased NH4+ flux after the N addition, followed by a subsequent decrease near to the initial level. In situ microdialysis sampling showed that the total amino acid fluxes were 5–15 nmol N cm-2 h-1 and they dominated the total diffusive N fluxes in Lapinjärvi and Kiikala. On average, the smallest share of the total free amino acids (54 %) was observed at the control plots of the logging residue experiment in Lapinjärvi. No correlation between the KCl-extractable NH4+-N concentration and the diffusive NH4+ flux was found, but instead the KCl-extractable NH4+-N concentration showed a significant positive correlation with the diffusive fluxes of both total free amino acid N and nitrate. Moreover, the diffusive NH4+ flux correlated positively with the net N mineralization rate. In general, ex situ microdialysis sampling showed 2–10 times higher amino acid fluxes and 10–20 times higher ammonium fluxes than the in situ microdialysis that reflects the effect of sampling, sample storage and preparation. The effect of soil moisture on the diffusive N fluxes could be further studied in laboratory experiments and in situ. The results of this study showed that the diffusive fluxes of different N forms are decoupled from the bulk soil concentrations. Moreover, microdialysis could be possibly used to quantify the transformation processes of N compounds in soil. These results increase the evidence that microdialysis has potential to detect temporal changes in N fluxes and possibly give new information about the ongoing processes at soil microsites.
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(2016)The use of forest chips has increased rapidly in the past 15 years and the usage must be increased even more in order to achieve the renewable energy usage goals. Forest chips are produced mainly from logging residues and stumps collected from clear cutting areas. One source is also small sized trees harvested from thinning areas. Increasing the use of forest chips could be possible, but the problem are the long transportation distances of the raw material. Most of the wood chip potential is located in Eastern and Central Finland and Kainuu, but the heat and power plants and demand are located by the sea. Transportation costs must be reduced to make usage possible. This was a pioneer study to develop working models for loading energy wood trucks. The aim of this study was to create systematic working models for loading logging residuals and stumps to bioenergy trucks to increase payload. The optimal load weight and its relation to transportation distance was also the point of interest. Twelve operators participated the study and the data was collected in Southern and Eastern Finland between April and September. The data set included 12 stump loads and 11 logging residual loads. The work researcher sat next to the driver, interviewed him about loading techniques and collected information about the loads. The loading events were also recorded by video camera for later performed time and observation studies. To compare the drivers the payloads were weighted. Drivers’ loadings where observed and analyzed with the payload weights and the loading times and as a result four different working models were developed. For stump material two different working models were described by the size of the stump: for small sized stump and normal sized stump. The working model for normal sized stumps was divided into two working models to achieve a large payload and an average payload with minimal loading time. For logging residues only one working model was necessary to describe. Working models consisted of systematic ways of work and different types of compressing methods and tricks. The average loading time towards one ton for stumps was 2.7 minutes and for logging residuals 2.2 minutes. Aiming for large payload is not always the most cost-efficient choice. The operator should consider the transportation distance as well as loading time along with the payload. The longer the driving distance the larger the payload should be. With shorter distances it is optimal to use less time for the loading even tough large payloads will not be achieved and use the spared time for driving of extra loads.
Now showing items 1-3 of 3