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  • 1.
    Dodoo, Ambrose
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Gustavsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Sathre, Roger
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Primary energy implications of ventilation heat recovery in residential buildings2011In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 43, no 7, p. 1566-1572Article in journal (Refereed)
    Abstract [en]

    In this study, we analyze the impact of ventilation heat recovery (VHR) on the operation primary energy use in residential buildings. We calculate the operation primary energy use of a case-study apartment building built to conventional and passive house standard, both with and without VHR, and using different end-use heating systems including electric resistance heating, bedrock heat pump and district heating based on combined heat and power (CHP) production. VHR increases the electrical energy used for ventilation and reduces the heat energy used for space heating. Significantly greater primary energy savings is achieved when VHR is used in resistance heated buildings than in district heated buildings. For district heated buildings the primary energy savings are small. VHR systems can give substantial final energy reduction, but the primary energy benefit depends strongly on the type of heat supply system, and also on the amount of electricity used for VHR and the airtightness of buildings. This study shows the importance of considering the interactions between heat supply systems and VHR systems to reduce primary energy use in buildings.

  • 2.
    Eivazihollagh, Alireza
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Svanedal, Ida
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    On chelating surfactants: Molecular perspectives and application prospects2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 278, p. 688-705Article in journal (Refereed)
    Abstract [en]

    Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.

  • 3.
    Ekman, Martin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Infiltrationsom ett extrasteg i rening av avloppsvatten2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Avloppsvatten kan innehålla föroreningar och smittoämnen som kan påverka både miljön och människors hälsa negativt. En vanlig metod för att rena avloppsvatten i mellannorrland är med så kallade fällningsdammar. De ger goda resultat med tanke på vattenkvalitet, men kvaliteten kan höjas ytterligare genom ett poleringssteg i form av infiltrationsdammar. I Björnrike finns en anläggning bestående av både fällningsdammar och infiltrationsdammar.

    Syftet med denna rapport är redogöra för den undersökningen jag har gjort på uppdrag från Härjedalens kommun. Undersökningen syftade till att visa effekterna som infiltrationsdammar har på avloppsvatten, vilket först har renats genom fällningsdammar. För att undersöka detta gjordes fältmätningar i Björnrikes anläggning, där vattenprover togs och sedan analyserades.

    Analysresultaten och slutsatserna av dessa visar att infiltrationsdammar fyller sin funktion som poleringssteg vid rening av avloppsvatten. Infiltrationsdammarna hade positiv påverkan på majoriteten av de parametrar som undersöktes, även om påverkan var knappt märkbar i vissa fall.

  • 4.
    He, Jie
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Zhang, Wennan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Techno-economic evaluation of thermo-chemical biomass-to-ethanol2011In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 88, no 4, p. 1224-1232Article in journal (Refereed)
    Abstract [en]

    Bio-ethanol has received considerable attention as a basic chemical and fuel additive. Bio-ethanol is presently produced from sugar/starch materials, but can also be produced from lignocellulosic biomass via hydrolysis-fermentation route or thermo-chemical route. In terms of thermo-chemical route, a few pilot plants ranging from 0.3 to 67 MW have been built and operated for alcohols synthesis. However, commercial success has not been found. In order to realize cost-competitive commercial ethanol production from lignocellulosic biomass through thermo-chemical pathway, a techno-economic analysis needs to be done. In this paper, a thermo-chemical process is designed, simulated and optimized mainly with ASPEN Plus. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost. Calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built around 200 MW. Cost-competitive ethanol production can be realized with efficient equipments, optimized operation, cost-effective syngas cleaning technology, inexpensive raw material with low pretreatment cost, high performance catalysts, off-gas and methanol recycling, optimal systematic configuration and heat integration, and high value byproduct.

  • 5.
    Jalilzadehazhari, Elaheh
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Minimizing CO2 emission by following ZEB strategies2014Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    AbstractBuildings play an important role in formulating sustainable development, which can help todecrease environmental impacts, such as energy resource depletion, environmental deteriorationand climate change due to the use of fossil base fuels. The zero energy/emission concept isgaining interest as a renewable energy resource. These types of buildings consist of two designstrategies: minimizing the total energy demand (heat demand in cold climate) through energyefficientmeasures)EEM (and adapting renewable energy resources and technologies (RET) toreduce environmental impacts. This thesis tries to determine the potential of single-family housesin reducing total energy consumption and CO2 emission by converting them to zeroenergy/emission buildings in Sweden. To fulfill the goal of this thesis, six different single-familyhouses were selected randomly from the last six decades. Improving the buildings‟ conditionsand reducing the energy demand through EEM and RET can have several side effects on thebuildings‟ thermal indoor climate and air quality.The results of this thesis show the undeniable potential of the residential sector, practically oldbuildings, in reducing energy consumption and CO2 emission. The results of the energycalculations show that in the average case, it is possible to reduce the CO2 emissions to 440.5kg/year in a single-family house by converting the house to a zero energy building (ZEB). Since2000, by using more electrical equipment and devices and leaving them in standby mode, energyconsumption has increased, which directly connects to peoples‟ living habits. Further researchmay be required for climate change, life-cycle cost and environmental impacts and social policy.

  • 6.
    Kajsa, Ignberg
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Struvit i Skövde biogasanläggning: En studie av struvitpåväxt i rör och alternativa lösningar för att minska problemet och dess uppkomst2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal with the study has been to find methods for cleaning and prevention of struvite at Skövde biogasanläggning (biogas plant). This to increase the efficiency and resource optimize the biogas plant and in that way get closer to a sustainable development of the society. Struvite (magnesiumammoniumphosphate hexahydrate) is a white, harsh mineral that commonly occurs in pipes, heat exchangers, pumps, and centrifuges at wastewater plants and after digestion processes at biogas plants. Struvite precipitates as a result of pH, temperatures, concentrations and supersaturation. Pipe material can also contribute. The study has been conducted through study visits and analyses of digestate and struvite at Skövde biogasanläggning to find the amount of struvite that can precipitate and where at the plant this happens. A simple benchmarking has been conducted, which shows that struvite precipitation at biogas plants mainly occurs in heat exchangers and that the fouling is temperature dependent. Materials and chemicals have been studied to find methods for cleaning and prevention of struvite. The study has shown that struvite mainly occurs in the heat exchanger and in pipe bends at the biogas plant and that it is dependent of the pH, supersaturation, temperature and high concentrations of phosphorous, magnesium and ammonium. A theory has been made from the study that the mineral first appears in the chamber between the digesters and heat storage tank. The study further shows that the most effective methods to clean fouling of struvite is to by hand chip the mineral alternatively replace the pipes. To prevent fouling of pipes a combination of methods is recommended, which minimizes the energy usage at the plant and prevent stops in the biogas production. Chemicals should be used if crystallization is to be completely stopped. The chemicals should be added in the above- mentioned chamber. Also planned maintenance should be conducted to minimize fouling. The pipes that are to be replaced should be replaced with pipes made of plastic materials. By doing this the resource efficiency increases and unnecessary environmental impact of the plant is avoided. The study has only included a rough cost analysis. To further support the above- mentioned methods a deeper economic analysis is recommended, which should include a study of chemical dosage and inspection sites for planned maintenance. 

  • 7.
    Mahapatra, Krushna
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Nair, Gireesh
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Gustavsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Swedish energy advisers' perceptions regarding and suggestions for fulfilling homeowner expectations2011In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, no 7, p. 4264-4273Article in journal (Refereed)
    Abstract [en]

    Municipality energy advice services were re-introduced in Sweden in 1998 as a way of advising end-users, mainly owners of detached houses, on energy issues. In this paper, we investigate Swedish energy advisers' perceptions of homeowners' awareness of the energy advice service and their perceived ability to fulfil homeowners' expectations. Our study is based on a mail-in questionnaire survey conducted in 2009 and distributed to municipality energy advisers in all municipalities in Sweden. About 66% of the energy advisers responded. The results show that 43% of the energy advisers thought that fewer than 50% of the homeowners were aware of the service and that mass media advertisements and presentations at different organisations could improve homeowner awareness. Energy adviser attitudes, job satisfaction, and the perception that the advisers possessed up-to-date and good knowledge and sufficient financial resources to execute their duties had a significant influence on their perceived ability to fulfil homeowner expectations. Increased training in technical aspects of energy measures and increased financial support were the two measures most widely suggested as a means to improve energy advisers' performance.

  • 8.
    Mangoyana, Robert Blessing
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Bioenergy from forest thinning: Carbon emissions, energy balances and cost analyses2011In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 36, no 9, p. 2368-2373Article in journal (Refereed)
    Abstract [en]

    The growing demand for bioenergy in Sweden has drawn attention to the potential of forest thinning as bioenergy feedstock. There are, however, concerns regarding the cost effectiveness and environmental challenges of harvesting and processing forest thinnings into bioenergy. It is against this background that cost, energy and carbon balances were analysed to evaluate some of the economic and environmental sustainability issues of forest thinning based bioenergy systems. Primary data was collected from two thinning operations in two forest plots comprising spruce and birch stands. One operation involved the use of the conventional two machines (one separate machine for cutting or felling and another for forwarding felled trees) for the thinning work. The second operation involved a harwarder, which combines tree felling/cutting and forwarding in one unit machine. The results showed that forest thinnings provide a potential resource for the sustainable production of bioenergy. (C) 2011 Elsevier Ltd. All rights reserved.

  • 9.
    Sathre, Roger
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Gustavsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Time-dependent climate benefits of using forest residues to substitute fossil fuels2011In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 35, no 7, p. 2506-2516Article in journal (Refereed)
    Abstract [en]

     In this study we analyze and compare the climate impacts from the recovery, transport and combustion of forest residues (harvest slash and stumps), versus the climate impacts that would have occurred if the residues were left in the forest and fossil fuels used instead. We use cumulative radiative forcing (CRF) as an indicator of climate impacts, and we explicitly consider the temporal dynamics of atmospheric carbon dioxide and biomass decomposition. Over a 240-year period, we find that CRF is significantly reduced when forest residues are used instead of fossil fuels. The type of fossil fuel replaced is important, with coal replacement giving the greatest CRF reduction. Replacing oil and fossil gas also gives long-term CRF reduction, although CRF is positive during the first 10-25 years when these fuels are replaced. Biomass productivity is also important, with more productive forests giving greater CRF reduction per hectare. The decay rate for biomass left in the forest is found to be less significant. Fossil energy inputs for biomass recovery and transport have very little impact on CRF. (C) 2011 Elsevier Ltd. All rights reserved.

  • 10.
    Van de Griend, Martijn Johannes
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Tandsbyns avloppsreningsverk: Förstudie om effektivisering och åtgärdsprotokoll ur ett BOD perspektiv2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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