Swedish biogas is currently produced mainly by anaerobic digestion of sewage sludgeat sewage treatment plants, landfills and anaerobic digestion of household or industrialwaste. Also cattle ma-nure from farms can be used to produce biogas. Upgradingbiogas represents an increase in methane concentration from about 65 % to about 97%. In addition, particles and contaminants must be sepa-rated from the upgradedbiogas. There are various methods for upgrading and this report compares sixdifferent methods with respect to environment and economy: water scrubber,Biosling, cryo technology, chemical absorption, Pressure Swing Adsorption (PSA) andmembrane separation.According to the used ORWARE model, chemical adsorption with amine has the leastenvironmen-tal impact (methane emissions) and the lowest costs.

Biogas is a renewable energy source that is produced by anaerobic digestion of organic mate-rial. In Sweden, biogas predominately comes from sewage water sludge and landfills or from organic waste of households and industries. Small scale digestion plants at farms are espe-cially expected to contribute to increased biogas production in the future. Biogas can be ob-tained directly in it?s raw form and used as fuel in a combustion chamber.

The Swedish production of biogas was 1,5 TWh 2011. About half of the production was used as vehicle fuels. The cost for upgrading biogas depends on the size of the biogas plant and its gas production. If the gas flow is low the cost will be high. However, further development of existing upgrading technologies or development of new ones, have good potential to decrease the upgrading cost for small scale biogas plants.

Because of the increasing trends in energy consumption and increased environmental awareness, greater focus has been placed on improvement and development of renewable energy sources. An already proven and accepted method is biogas production from anaerobic digestion at municipal wastewater treatment plants.In the waste water treatment process solid material and dissolved pollutants are separated from the water, forming a sludge. The sludge is separated from the process and stabilized during anaerobic digestion or aerobic aeration. Most often, mesophilic anaerobic digestion is used. Because of degradation by microorganisms, biogas with a high content of methane is formed during the digestion.

In order to reduce greenhouse gas emissions from human activities fossil fuels will have to be replaced with renewable energy alternatives, such as bioenergy. Sweden has a great potential to produce bioenergy derived from forest products and there is currently a great interest within Sweden in using stumps for bioenergy production. However, the environmental consequences of the method need to be investigated before stump removal can be performed on a large scale. Swedish forest soils contain large carbon pools and a different land use may change conditions so that soils that presently act as sinks of carbon could potentially turn into sources of carbon release instead. This study investigates the initial effects of stump harvesting on the emissions of three greenhouse gases, carbon dioxide, methane and nitrous oxide. The emissions were measured from the soil surface in a Norway spruce forest located in the southern part of Sweden.

Freshwater ecosystems have long been neglected as an important part of the global carbon cycle. However, research shows that most of the world?s lakes are net-heterotrophic and consequently emitters of greenhouse gases to the atmosphere. In many boreal and north-temperate lakes, most of the yearly emissions usually occur in spring, shortly after ice-thaw. The aim of this study was to quantify the flux of carbon dioxide (CO2) and methane (CH4) in three boreal lakes, during this annual event.

A growing interest for the climate and the environment has led to an increased interest forenvironmentally friendly and renewable energy sources, such as biogas. Planning new biogasplants requires a decision basis including facts about approximate amounts of biogas possibleto produce at the plant. The purpose of this thesis is to develop a model that calculates theapproximate biogas and digestate production from a planned or existing biogas plant.Developing the model required a literature review and studies of calculations concerningbiogas and digestate production performed by WSP Sweden AB. As a complement to themodel development, facts about substrates for biogas production were compiled through aliterature review. In addition the Methane potential from selected materials was determined bybatch experiments.

Feed costs constitute a large part of the expenses of dairy farmers. Pasture is a high quality feed with a low cost. However, feeding with concentrates has been shown to enhance milk yield (Leaver, 1985; Bargo et al., 2003; Stockdale, 2004). The purpose with this study was to investigate how milk yield and milk composition were affected as the concentrate proportion in the diet decreased. Pasture behaviour was examined to see if the different concentrate levels affected the time cows spent grazing and ruminating.

Biogas is increasingly used for fuel in for example vehicles and it´s produced in a biogas processconsisting of the steps of pretreatment, digestion and gas cleaning. The pretreatment is a method usedto increase the gas production and / or destroy pathogens. The digestion is the stage when anaerobicmicroorganisms convert bio-mass of a substrate to a raw gas containing about 65% of methane. Thegas cleaning is used to increase the methane content to about 97% so the gas can be used for motors invehicles. The biogas part of the Ekeby sewage plant in Eskilstuna is using multiple substrates.

An analysis of a specific application of anaerobic wastewater treatment at a pulp and board mill, Stora Enso Skoghall, was carried out. A literature study was done and effluent wastewater from CTMP pulp production was analyzed. The analysis consisted of a broad constituent analysis and an anaerobic treatment trial. Results from these test where used to calculate the treatment effectiveness and resulting energy potential at the mill.The literature study and constituent analysis showed that toxicity of the water to be treated, due to wood extractives and sulphur content, was of concern. Detoxification chemicals targeting these constituents where used in the anaerobic treatment trial.

An analysis of a specific application of anaerobic wastewater treatment at a pulp and board mill, Stora Enso Skoghall, was carried out. A literature study was done and effluent wastewater from CTMP pulp production was analyzed. The analysis consisted of a broad constituent analysis and an anaerobic treatment trial. Results from these test where used to calculate the treatment effectiveness and resulting energy potential at the mill.The literature study and constituent analysis showed that toxicity of the water to be treated, due to wood extractives and sulphur content, was of concern. Detoxification chemicals targeting these constituents where used in the anaerobic treatment trial.

We derive the equation linking the Weyl tensor with its Lanczos potential, called the Weyl-Lanczos equation, in 1+3 covariant formalism for perfect fluid Bianchi type I spacetime and find an explicit expression for a Lanczos potential of the Weyl tensor in these spacetimes. To achieve this, we first need to derive the covariant decomposition of the Lanczos potential in this formalism. We also study an example by Novello and Velloso and derive their Lanczos potential in shear-free, irrotational perfect fluid spacetimes from a particular ansatz in 1+3 covariant formalism. The existence of the Lanczos potential is in some ways analogous to the vector potential in electromagnetic theory. Therefore, we also derive the electromagnetic potential equation in 1+3 covariant formalism for a general spacetime.

This paper analyses the potential extent of labour mobility in the European Union after the eastern enlargement that took place in 2004, but focuses on movements from the 10 new member countries to the old EU -members. In this study, a number of economic models are used to investigate if there is a large potential for labour mobility in the enlarged EU and also if this potential has large effects on mobility in reality. The potential for labour mobility is, to a large extent, discussed in terms of theoretical migrating incitements for workers and different types of labour migration obstacles. Many factors indicate that such large potential for migration actually exists, mainly due to high difference in wages and unemployment and because of the common EU market. At the same time, the presence of natural and constructed obstacles is likely to restrict migration for a long period of time..

Högbytorp is Ragn-Sells? largest waste facility and it is located north of Stockholm. There is an old landfill still in use, but at the end of this year it will be closed. The waste deposited on the landfill can, through decomposition, give rise to a large amount of methane gas, which is an energy rich gas that can be used for heat and electricity production. To receive a relatively large amount of gas, the decomposition requires a high moisture content in the waste.

Målet med denna undersökning är att teoretiskt undersöka den vatten/litiumbromidbaserade absorptionsprocessens potential ombord fartyg då processen enbart drivs av huvudmaskinens högtemperaturkylvatten. Undersökningen genomförs teoretiskt mot tre olika fartyg samt Sjöfartshögskolan i Kalmars maskinrumssimulator. För vardera fartyg undersöks driftenergikällan och kylbehovet ombord. Med det som underlag dras en slutsats om den vatten/ litiumbromidbaserade absorptionsprocessens potential ombord fartyget. Fartygens resultat ligger till grund för slutsatsen.