Stump wood is a hot alternative when the heating plants demands more and more forest fuel. The aim with the study has bean to calculate the costs in four different systems for transportations of stump wood, examine if there are any differences in fuel quality for the stump wood in the different systems, analyse if the fuel quality in stump wood is affected with the time it lays by the road side and how much space the stump wood demands on the road side. To calculate the costs for the different systems a system analysis was carried out, where some of the costs were collected through field studies on Holmen Skog stump experiment and other costs were collected from literature and contacts. Data for the fuel quality study was collected from Eons heat plant in Norrköping. Data for the study of how much space stump wood takes along a roadside was collected from field studies.

Tasmania is a state in Australia, and is also the country?s largest island. It is separated from the main land by a 429 kilometer wide strait. Every year, a large amount of people, cars and goods are transported to the island using a government owned ferry line, which generates approximately 300 million Australian dollars to the state?s economy ,every year. This bachelor thesis investigates the possibility of reducing the fuel consumption for the ferry traffic to and from Tasmania, which would also reduce the overall cost.

The main purpose of this study is to investigate how to reduce the high, and every decade raising, pre-clearance cost. The pre-clearance is today carried out with a brush saw and paid per labour hour. All small trees not suitable for pulpwood are removed to simplify the later work of the harvester. The study compares the economic results from thinning of four parcels each treated differently regarding harsh or light pre-clearance and extraction of only pulpwood, or both pulpwood and fuel wood. In this type of spruce stand the study indicates that a lighter pre-clearance, followed up with both pulpwood and a fuel wood extraction, has a much better economy than the traditional method of hard pre-clearance and only pulpwood extraction..

Regulations on the exhaust emissions of HD-diesel engines are becoming more and more stringent, and therefore, emission after-treatment systems are commonly used. These systems rely on catalytic conversion of NOx,CO , and HC emissions, and are thus dependant on temperature. At low load of the engine, exhaust temperatures are not sufficient for the after-treatment components. Therefore, means to increase the exhaust temperature while maintaining low emissions and fuel consumption are needed.The focus of this project has been to develop strategies for the lift profiles of exhaust and intake valves in the engine, with the goal to raise exhaust temperature in combination with low emissions and fuel consumption. The strategies have been tested in a single-cylinder research engine equipped with a hydraulic variable valve actuation system.

Metan är en stark växthusgas som är viktig att ta med i beräkningarna när det gäller klimatförändringar. Feedback från myrmarker vid en ökad temperatur i samband med klimatförändringar har diskuterats, bland annat eftersom myrmarker är en källa för metan till atmosfären. Det finns många faktorer som påverkar metanemission, och en av dom är vegetation. Olika sorts vegetation tros bidra olika mycket till avgivningen av metan. Syftet med denna studie var att undersöka hur stor betydelse det har att ta med olika växtsamhällens sammansättning i beräkningarna för att uppnå korrekta uppskattningar av metanemission från myrmark på ekosystemnivå.

Phytoremediation is a technique using the ability of plants to absorb pollutants in their biomass from contaminated soils and remediate it. The plants are then harvested and the soil gets purified. This method is more environmental-friendly than the normally used methods for soil remediation. Glasriket in Småland is an area with large amount of pollutants including arsenic, cadmium and lead. This area must be cleaned from these metals because of the high threat to the environment ant the health of people who live here.

In Sweden, there an increasing need for transport and this leads directly to fuel demand of the transport sector is expected to increase. Both politicians and industry believes that renewable fuels are a realistic and significant method to reduce the transport sector's environmental impact. This study aims to document the Swedish haulage contractor?s attitude to biodiesel. Also to document the strengths and weaknesses of biodiesel, based on opinions from the ultimate consumers.

The Swedish boreal forests are limited by nitrogen (N) availability. While biological N2 fixation by cyanobacteria hosted by pleurocarpous feather mosses are important sources of N input to natural boreal forest ecosystems, little is known about the patterns of N2 fixation in silvicultural systems. This study investigates the biological N2 fixation rates of two boreal feather moss species (Pleurozium schreberi and Hylocomium splendens) along a chronosequence from clear-cut to mature forest, as well as the vegetation characteristics along the chronosequence. Measurements and samples were collected from 32 forest sites that were classified into four age classes (clear-cut, pre-commercially thinned, thinned and mature forest). The sites were located near the city of Arvidsjaur in northern Sweden.

Fuel pellets are a refined bio fuel mostly consisting of residues from sawmills and wood industry. At Rindi Västerdala AB's combined bio energy plant in Vansbro fuel pellets are produced, while the waste heat from the process is used for district heating. The pellets are produced from sawdust, wood shavings and dry wood chips that is dried, milled and pressed into small cylindrical rods. The advantage of refining the wood material in this manner is that the energy value is greater per unit volume and unit weight, thereby the cost of transportation per energy unit is reduced. Also, less storage space is needed.Pellet manufacturing is a complex process since many parameters affects the final results.

With the elevated oil prices of today it is necessary to look for other heating alternatives. If the oil price continues to develop in the same way it has done the last years it will soon be impossible for many producing garden companies to survive. The purpose of this diploma work is to compare three different fuel options in order to find the most economic one considering the conditions of Katrinebergs Handelsträdgård AB. In relation to oil it is profitable to change to any of the three alternatives: wood chips, wood pellets and grain. The most profitable option is to change to wood chips. This alternative has a payoff time less than three years and after that the annual saving compared to the oil is relatively high. The annual cost is 65 % of the cost of the oil alternative.

Acidification is a central concept in the environmental debate. The effect of acidification of the soil is a matter of a decreasing amount of cations and thereby a decreasing ability to resist a supply of hydrogen ions to the soil. Acidification has gradually increased in the O horizon in Västerbotten over a 30-year period from the 1970th to the 1990th. The aim of this study was from inventories of The Swedish National Forest Soil Survey and The Swedish National Forest Inventory explain and quantify the acidification that has occurred in the O horizon of two regions in the north of Sweden. Data from SMHI, The Swedish Meteorological and Hydrological Institute, has also been used.

This thesis is done in cooperation with SWECO Energuide in Växjö. They have been assigned by SKB in Oskarshamn to renew their electrical power supply and the ancillary processing systems in their Central provisional storage of spent nuclear fuel, CLAB. Today in the CLAB facility, the spent fuel is cooled down with water pumps, driven by asynchronous induction motors, where the water is regulated by mechanical valves to the desired flow. After the upgrade, the engines will be powered by AC drives that can control the pumps by changing the rotational speed and thus change the water's cooling effect on the nuclear fuel. In this study, I investigated the interference AC drives causes the feeding network and how to go about averting them.

To make it easier for forestry planning the forest owners needs data which describe characteristics of the forest. Such data you usually get from some type of inventory. A relatively new technology which probably is getting more important in the future, is laser scanning because of lower costs. But because the laser technology is relatively new you need to compare it with conventional inventory technologies to get better understanding of the possibilities the laser technology gives. This work intends to estimate field measured characteristics of the forest from laser data with help of regression analysis and then see which of the field measured properties that best could be estimated and which laser variables that gave the best results. This study shows that heights has the best estimates, but biomass, diameter and volume also gives good estimates.

The study was carried out as a time study of five wood chippers placed on trucks,so?called huggbilar. They are trucks with built?in wood chipper, chip bowl and crane pulling a chip trailer. The system is used for chipping wood fuel, transporting, and delivering the chips to heating plants.

The market for biofuels from the forests have had a positive development and the job initiators for this master´s thesis wanted to examine the profitability of a method for harvesting forest fuel, which was unfamiliar to them. The method was the ?long tree tops-method?, here called the LT-method. The LT-method is characterised by the fact that timber is harvested as the only roundwood assortment while the rest of the stem, which in other cases would become pulpwood, is harvested as forest fuel together with the logging residues. The method is based on the assumption that advantages in handling of the forest fuel assortment such as increased load weights for forest hauling and truck transportation, should compensate for the lower price for pulpwood when sold as forest fuel. The aim of the study was to compare the profitability of the LT-method with the GROT-method (harvest of timber, pulpwood and logging residues) and conventional logging without any harvest of forest fuel, and aslo to try to identify factors affecting the profitability of the different methods.