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  • 1.
    ERASIN, BR
    et al.
    CRANFIELD UNIV,CRANFIELD BIOTECHNOL CTR,BEDFORD MK43 0AL,ENGLAND; .
    TURNER, APF
    Cranfield University, UK.
    WHEATLEY, AD
    CRANFIELD UNIV,CRANFIELD BIOTECHNOL CTR,BEDFORD MK43 0AL,ENGLAND; .
    A FIXED-FILM BIOASSAY FOR THE DETECTION OF MICROPOLLUTANTS TOXIC TO ANAEROBIC SLUDGES1994In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 298, no 1Article in journal (Refereed)
    Abstract [en]

    Micropollutants in waste water streams can be a serious problem for the anaerobic digestion process. A short-term acute bioassay system is described for testing the effects of new and potentially toxic compounds on anaerobic digestion processes. Change in methanogenic activity was used as the monitored process parameter and the performance of intoxicated inocula was compared to activity prior to adding test compounds and to the activity of a parallel control assay. The performance of the bioassay was tested with chlorinated solvents and heavy metals. Trichloroethane caused a 50% reduction in methanogenic activity at 7 mg/l assay. The performance of suspended and fixed biomass assays were compared; the suspended growth was found to be five times more sensitive to trichloroethane. There was no clear inhibition with the heavy metals even at the highest concentration used (up to 750 mg Cu/l). The duration of assay was found to be an important parameter in the evaluation of anaerobic toxicity.

  • 2.
    Smith, G
    et al.
    Chalmers Univ Technol, Dept Radio & Space Sci, S-41296 Gothenburg, Sweden Swedish Def Res Estab, FOA, Dept Surveillance Radar, Linkoping, Sweden.
    Ulander, LMH
    Chalmers Univ Technol, Dept Radio & Space Sci, S-41296 Gothenburg, Sweden Swedish Def Res Estab, FOA, Dept Surveillance Radar, Linkoping, Sweden.
    A model relating VHF-band backscatter to stem volume of coniferous boreal forest2000In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, Vol. 38, no 2, 728-740 p.Article in journal (Refereed)
    Abstract [en]

    A physical model is presented describing the backscatter from coniferous boreal forests in the lower VHF-band in terms of Stem volume. By using measurements of mean amplitude in high-resolution SAR images (rather than intensity), a linear dependence on stem volume can be obtained. The model fits well with the measurements made using the coherent all radio band sensing (CARABAS) SAR in the southern boreal forest, indicating the possibility of retrieving stem volume, and hence biomass, with an accuracy similar to that reached by standard ground-based measurements. No saturation of the scattering is seen up to biomasses of 550 m(3)/ha.

  • 3.
    Fayle, Tom M
    et al.
    University Museum Zoology, Cambridge.
    Bakker, Lieneke
    University Putra Malaysia.
    Mui Ching, Tan
    University Putra Malaysia.
    Davey, Alexandra
    New Guinea Binatang Research Centre.
    Earl, Adam
    Tmn Kingfisher.
    Hyland, Steve
    Linköping University. Linköping University, Faculty of Health Sciences.
    Ligtermoet, Emma
    Danum Valley Field Centre.
    Kai Lin, Ling
    University Malaysia Sabah.
    Phouthakone, Luangyotha
    Wildlife Conservation Society.
    Herlander Martins, Bruno
    Wildlife Conservation Society.
    Kepfer Rojas, Sebastian
    New Guinea Binatang Research Centre.
    Phuong Thi, Thanh Sam
    Bogor Agriculture University.
    Wahyudi, Agus
    Dipterocarp Research Centre.
    Walsh, Judy
    Malahide Co.
    Weigl, Stefanie
    University of Bristol.
    Jehle, Robert
    University of Salford.
    Metcalfe, Dan
    CSIRO Sustainable Ecosyst, Atherton.
    Trevelyan, Rosie
    Trop Biol Association.
    A positive relationship between ant biodiversity (Hymenoptera: Formicidae) and rate of scavenger-mediated nutrient redistribution along a disturbance gradient in a south-east Asian rain forest2011In: MYRMECOLOGICAL NEWS, ISSN 1994-4136, Vol. 14, 5-12 p.Article in journal (Refereed)
    Abstract [en]

    Human modification of pristine habitats almost always leads to the local extinction of a subset of the species present. This means that the ecosystem processes carried out by the remaining species may change. It is well documented that particular species of ants carry out important ecosystem processes. However, while much work has been carried out to investigate the link between biodiversity and ecosystem functioning in other taxa, this has received relatively little attention for ant communities. In particular, no attempt has been made to link levels of ant diversity with the rates of nutrient redistribution carried out by scavenging species. Here we investigate the impacts of anthropogenic disturbance on the rate of scavenger-mediated nutrient redistribution, using bait-removal rate as a surrogate measure. We found that although ant species richness, diversity, biomass and rates of bait removal did not change systematically across the disturbance gradient, the rate of bait removal was related to ant species richness. Sites with more ant species experienced a faster rate of bait removal. This is the first documented positive relationship between ant species richness and the rate of an ecosystem process. If these results are applicable at larger spatial scales for a wider range of nutrient sources, loss of ant species could lead to important changes in the way that ecosystems function.

  • 4.
    Paulsson, Dan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Gustavsson, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Mandenius, Carl-Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    A Soft Sensor for Bioprocess Control Based on Sequential Filtering of Metabolic Heat Signals2014In: Sensors, ISSN 1424-8220, Vol. 14, no 10, 17864-17882 p.Article in journal (Refereed)
    Abstract [en]

    Soft sensors are the combination of robust on-line sensor signals with mathematical models for deriving additional process information. Here, we apply this principle to a microbial recombinant protein production process in a bioreactor by exploiting bio-calorimetric methodology. Temperature sensor signals from the cooling system of the bioreactor were used for estimating the metabolic heat of the microbial culture and from that the specific growth rate and active biomass concentration were derived. By applying sequential digital signal filtering, the soft sensor was made more robust for industrial practice with cultures generating low metabolic heat in environments with high noise level. The estimated specific growth rate signal obtained from the three stage sequential filter allowed controlled feeding of substrate during the fed-batch phase of the production process. The biomass and growth rate estimates from the soft sensor were also compared with an alternative sensor probe and a capacitance on-line sensor, for the same variables. The comparison showed similar or better sensitivity and lower variability for the metabolic heat soft sensor suggesting that using permanent temperature sensors of a bioreactor is a realistic and inexpensive alternative for monitoring and control. However, both alternatives are easy to implement in a soft sensor, alone or in parallel.

  • 5.
    Liu, Linn
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    A systematic approach for major renovation of residential buildings2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Sweden, buildings are responsible for about 40 % of total energy use and about 10 % of total CO2 emissions Today more than 60 % of existing Swedish residential buildings are over 40 years old and are in need of major renovation. In addition, 15 % of all multi-family buildings and 27 % of all single-family houses were built before 1945. The increased energy use and threat from CO2 emissions of the building sector create a need for energy efficiency. The important role that renovation of residential buildings will play in reducing the total energy used by the Swedish building sector as well as in reducing primary energy use and CO2 emissions on both the national and global levels has been the impetus for the studies included in this thesis.

    The aim of the current research is to develop a methodology from a system perspective which can be used to analyze the energy use, optimal life cycle cost (LCC), energy efficiency measure (EEM) package, indoor environment, CO2 emissions, and primary energy use of a building or a community during major renovation. The developed methodology accomplished at three different levels, i.e. building level, cluster level and district level. The methodology considers both energy efficiency and economic viability during building renovation and will also play an important role in overall urban planning. The studied buildings include both non-listed and listed residential buildings and the tools used include building energy simulation (BES), survey, technical measurements, LCC optimization and building categorization.

    The results show that the combination of BES, technical measurements and surveys provides a holistic approach for evaluation of energy use and indoor environment of the studied residential buildings. The results from the current study also show that the 2020 energy target, i.e., reduction of energy use by 20 %, for the building sector can be achieved by all the studied building types and that the total LCC of these buildings are below the cost-optimal point. In comparison, the 2050 energy target, i.e., reduction of energy use by 50 %, for the building sector may be achieved by the non-listed buildings, but when the constraints relevant to listed buildings are added the cost-optimality changes as some EEMs in direct conflict with the building’s heritage value may not be implemented.

    The investigation of primary energy use and CO2 emissions by the residential buildings show that the higher the energy saving, the lower the primary energy use becomes, and vice versa. With the same energy saving, the heating system with higher primary energy factor results in higher primary energy use. From a CO2 emissions point of view, EEM packages proposed to help buildings connected to a CHP based district heating system, to reduce the energy use or LCC are not consistently effective. Since these EEM packages will reduce district heating demand, the electricity produced in the CHP plant will also decrease. When the biomass is considered a limited resource, measures such as investment in a biofuel boiler are not favourable from the CO2 emissions point of view. The current study has also shown that combining building categorization method and LCC optimization method will help the community to reduce its energy use, primary energy use and CO2 emissions in a systematic and strategic way.

    List of papers
    1. Comprehensive investigation on energy retrofits in eleven multi-family buildings in Sweden
    Open this publication in new window or tab >>Comprehensive investigation on energy retrofits in eleven multi-family buildings in Sweden
    2014 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 84, 704-715 p.Article in journal (Refereed) Published
    Abstract [en]

    Rapidly growing energy use in the building sector is considered a serious problem by both the European Union (EU) and Sweden. Reducing energy demand in the building sector is important for Sweden in order to reach national energy goals for reduced energy use and CO2 emissions in the future. This project aims to find energy efficiency potential in multifamily buildings in the Gävleborg region, which is a cold climate region in Sweden. Measurements and simulations have been made on eleven multifamily buildings from the whole region. The results include different energy efficiency measure packages, profitability analysis of individual measures and packages, and primary energy use analysis. The paper also includes CO2 emissions reduction analysis based on different methods. The project shows that the multifamily buildings in the Gävleborg region have good potential to reduce their energy use by more than 50%, which in turn will contribute to 43% primary energy reduction and 48% CO2 emissions reduction.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-111051 (URN)10.1016/j.enbuild.2014.08.044 (DOI)000345182000070 ()
    Available from: 2014-10-06 Created: 2014-10-06 Last updated: 2017-05-16Bibliographically approved
    2. Evaluating indoor environment of a retrofitted multi-family building with improved energy performance in Sweden
    Open this publication in new window or tab >>Evaluating indoor environment of a retrofitted multi-family building with improved energy performance in Sweden
    2015 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 102, 32-44 p.Article in journal (Refereed) Published
    Abstract [en]

    The building sector within both the EU and Sweden accounts for about 40% of total energy use. It is therefore important to introduce energy efficiency measures in this sector in order to meet the national implementation of the Building Performance Directive. Retrofits that result in improved energy performance are important in order to meet national energy targets, but the impact on the indoor environment has to be considered. Properly chosen energy efficiency measures may affect the indoor environment positively. One retrofitted multi-family building, located in the city of Linkoping, Sweden, was chosen as the study object. The building represents a common type of construction in Sweden. This study presents an evaluation of both the indoor environment and energy use of the retrofitted building in comparison with a similar non-retrofitted building from the same area. The results show that the building has potential to reach a 39% reduction of space heating demand. The indoor environment has been improved compared to the non-retrofitted building. Adding external blinds from 15 May to 15 September between 10am-12pm on the east side and 12pm-3pm on the west side seems to be the best option for improving the indoor climate during summer. (c) 2015 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Multi-family building; Retrofit; Building energy simulation; Energy use; Indoor environment
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-120720 (URN)10.1016/j.enbuild.2015.05.021 (DOI)000358458100003 ()
    Note

    Funding Agencies|Swedish Energy Agency

    Available from: 2015-08-24 Created: 2015-08-24 Last updated: 2017-05-16
    3. A Method to Assess the Potential for and Consequences of Energy Retrofits in Swedish Historic Buildings
    Open this publication in new window or tab >>A Method to Assess the Potential for and Consequences of Energy Retrofits in Swedish Historic Buildings
    Show others...
    2014 (English)In: The Historic Environment: Policy & Practice, ISSN 1756-7505, E-ISSN 1756-7513, Vol. 5, no 2, 150-166 p.Article in journal (Refereed) Published
    Abstract [en]

    The Swedish research project Potential and Policies for Energy Efficiency in Swedish Historic Buildings aims to investigate the interdependency between political energy targets and effects on the built heritage. The first part of this paper presents an iterative and interactive method to assess the potential for and consequences of improving the energy performance in a stock of historic buildings. Key elements in the method are: categorisation of the building stock, identifying targets, assessment of measures, and life-cycle cost optimisation. In the second part of the paper, the method is applied to a typical Swedish building. The selected case study shows how the method allows for an interaction between the quantitative assessment of the techno-economic optimisation and the qualitative assessment of vulnerability and other risks. Through a multidisciplinary dialogue and iteration it is possible to arrive at a solution that best balances energy conservation and building conservation in a given decision context.

    Place, publisher, year, edition, pages
    Maney Publishing, 2014
    Keyword
    cultural significance; energy efficiency; heritage values; historic buildings; life-cycle cost
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-109231 (URN)10.1179/1756750514Z.00000000055 (DOI)000338773000006 ()
    Available from: 2014-08-12 Created: 2014-08-11 Last updated: 2017-05-16Bibliographically approved
    4. LCC assessments and environmental impacts on the energy renovation of a multi-family building from the 1890s
    Open this publication in new window or tab >>LCC assessments and environmental impacts on the energy renovation of a multi-family building from the 1890s
    2016 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 133, 823-833 p.Article in journal (Refereed) Published
    Abstract [en]

    The 2020 and 2050 energy targets increase requirements on energy performance in the building stock, thus affecting both listed and non-listed buildings. It is important to select appropriate and cost-optimal energy efficiency measures, using e.g. Life Cycle Cost (LCC) optimization. The aim of this paper is to find cost-optimal packages of energy efficiency measures (EEMs) as well as to explore the effects of specific predesigned energy target values for a listed Swedish multi-family building from the 1890s. The purpose is also to show the effects on energy use, LCC, primary energy use and CO2 emissions of different energy targets, discount rates, electricity prices and geographic locations. The results show that separate energy targets could be an effective way to simplify the implementation for listed buildings. Furthermore, a cost-optimal package of EEMs is more sensitive to changes in discount rate than in electricity price. The energy renovation has impact on the primary energy use and CO2 emissions. The lower the discount rate is, the more EEMs will be implemented and the easier the national energy targets may be achieved. A higher electricity price also leads to more EEMs being implemented but at the same time higher running costs. (C) 2016 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE SA, 2016
    Keyword
    LCC assessments; Environmental impacts; Energy efficiency measures package; Listed/non-listed building; Renovation; Energy targets
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-133507 (URN)10.1016/j.enbuild.2016.10.040 (DOI)000389087300072 ()
    Note

    Funding Agencies|Swedish Energy Agency

    Available from: 2016-12-30 Created: 2016-12-29 Last updated: 2017-05-16
  • 6.
    Pauline, Ekoff
    et al.
    Linköping University, Department of Mechanical Engineering.
    Johanna, Lund
    Linköping University, Department of Mechanical Engineering.
    Absorptionskyla i Linköpings energisystem: kompressorkyla vs absorptionskyla2006Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    The main purpose of this thesis has been to look in to the potential of a production of district cooling using heat as the source of power, i.e. absorptions cooling, in the energy system of Linköping. In the light of the fact that many energy companies are looking for new markets for district heating due to the surplus of heat in the summertime in an energy system with CHP (Combined Heat and Power). Furthermore, the price on electricity is expected to continue to rise since Sweden is most likely to follow Europe’s lead and embrace a power dimensioned energy system. As a result of that transition, energy efficient measures will be more important and absorption cooling implies that more electricity can be produced, instead of consumed, in a CHP system.

    There are two different types of absorption cooling machines available in the market, with either district heating or steam as the source of power. A machine using district heating as the source of power is most suitable to produce comfort cooling i.e. the cold does not need to attain such low temperatures. A steam driven absorption cooling machine is able to attain the very low temperatures needed for cooling used in the processing industry. A condition for absorption cooling is the access to low-cost heat/steam. Tekniska Verken (an energy company) has due to waste incineration access to low-cost heat. The steam in the energy system is produced with oil and electricity, which makes it more expensive to generate absorption cooling with steam as the power source.

    A casestudy was preformed at two industries in Linköping, Linköpingsmejeriet and Swedish Meats, where the possibility for connection of district cooling was examined. Mainly the cooling needed in the processing industry has been examined as this is need is considerably larger than the need for comfort cooling. A number of cases with different conditions for producing district cooling have been simulated in MODEST. The following conclusions have been drawn based on the results of the simulations.

    • In the energy system of today there is not enough steam production to fulfil both the current need for steam and the amount of steam needed for cooling production.

    • An investment in new CHP-plants using biomass fuels will generate enough heat and steam to be profitable for cooling production using heat as a source of power.

    • The emission of carbon dioxide will decrease as a result of the transmission from compression cooling to absorption cooling. The emission will decrease further if an investment in new CHP plants with biomass fuels is carried out. This will then replace the use of fossil fuels.

    • An investment in lithium bromide absorptions cooler will not be profitable with such a small demand as the one in question.

  • 7.
    Sundh, Ingvar
    et al.
    Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Tranvik, Lars J.
    Limnology, Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Abundance, activity, and community structure of pelagic methane-oxidizing bacteria in temperate lakes2005In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 71, no 11, 6746-6752 p.Article in journal (Refereed)
    Abstract [en]

    The abundance and activity of methane-oxidizing bacteria (MOB) in the water column were investigated in three lakes with different contents of nutrients and humic substances. The abundance of MOB was determined by analysis of group-specific phospholipid fatty acids from type I and type 11 MOB, and in situ activity was measured with a 14 CH, transformation method. The fatty acid analyses indicated that type I MOB most similar to species of Methylomonas, Methylomicrobium, and Methylosarcina made a substantial contribution (up to 41%) to the total bacterial biomass, whereas fatty acids from type 11 MOB generally had very low concentrations. The MOB biomass and oxidation activity were positively correlated and were highest in the hypo- and metalimnion during summer stratification, whereas under ice during winter, maxima occurred close to the sediments. The methanotroph biomass-specific oxidation rate (V) ranged from 0.001 to 2.77 mg CH4-C mg(-1) C day(-1) and was positively correlated with methane concentration, suggesting that methane supply largely determined the activity and biomass distribution of MOB. Our results demonstrate that type I MOB often are a large component of pelagic bacterial communities in temperate lakes. They represent a potentially important pathway for reentry of carbon and energy into pelagic food webs that would otherwise be lost as evasion of CH,.

  • 8.
    Lohm, Ulrik
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    Lundkvist, Helene
    Persson, Tryggve
    Abundance and biomass of some soil animals at the Stordalen mire1973Report (Other academic)
  • 9.
    Andersson, Viktor
    et al.
    Chalmers, Sweden.
    Broberg, Sarah
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Hackl, Roman
    Chalmers, Sweden.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Berntsson, Thore
    Chalmers, Sweden.
    Algae-based biofuel production as part of an industrial cluster2014In: Biomass and Bioenergy, ISSN 0961-9534, Vol. 71, 113-124 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a study on the production of biofuels from algae cultivated in municipal wastewater in Gothenburg, Sweden. A possible biorefinery concept is studied based on two cases; Case A) combined biodiesel and biogas production, and Case B) only biogas production. The cases are compared in terms of product outputs and impact on global CO2 emissions mitigation. The area efficiency of the algae-based biofuels is also compared with other biofuel production routes. The study investigates the collaboration between an algae cultivation, biofuel production processes, a wastewater treatment plant and an industrial cluster for the purpose of utilizing material flows and industrial excess heat between the actors. This collaboration provides the opportunity to reduce the CO2 emissions from the process compared to a stand-alone operation. The results show that Case A is advantageous to Case B with respect to all studied factors. It is found that the algae-based biofuel production routes investigated in this study has higher area efficiency than other biofuel production routes. The amount of algae-based biofuel possible to produce corresponds to 31 MWfuel for Case A and 26 MWfuel in Case B.

  • 10.
    Bacos, M P
    et al.
    Office National d'Etudes et de Recherches Aérospatiales, France.
    Josso, P
    Office National d'Etudes et de Recherches Aérospatiales, France.
    Vialas, N
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Poquillon, D
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Pieraagi, B
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Monceau, D
    CIRIMAT––ENSIACET-INPT, Toulouse, France.
    Nicholls, J R
    Cranfield University, United Kingdom.
    Simms, N
    Cranfield University, United Kingdom.
    Encinas-Oropesa, A
    Cranfield University, United Kingdom.
    Ericsson, Torsten
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Stekovic, Svjetlana
    Linköping University, Department of Mechanical Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    ALLBATROS advanced long life blade turbine coating systems2004In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 24, no 11-12, 1745-1753 p.Article in journal (Refereed)
    Abstract [en]

    The scientific and technological objectives of this program are to increase the efficiency, reliability and maintainability of industrial gas turbine blades and vanes by

    • developing coatings that can warrant a 50 000 h life, i.e. twice that of the usual life, of the hot components (800–1100 °C) even with the use of renewable fuels such as biomass gas or recovery incinerator gas i.e. low-grade fuels with high pollutant levels,

    • characterising advanced existing coatings to assess lifetime and performance of coatings and coated materials,

    • providing material coating data and design criteria to use coating as a design element,

    • increasing the fundamental understanding of the behaviour of coated materials, their degradation, fracture mechanisms and engineering because of the strong need for a mechanism-based modelling of durability.

    These programmes permitted the selection of two reference coatings and the development of two innovative coatings. Concurrently work has been done in order to develop corrosion, oxidation and thermo-mechanical property models. Correlations between coatings development, experimental results and calculations will be discussed.

  • 11.
    Jansson, Rickard
    Linköping University, Department of Physics, Chemistry and Biology.
    An Assessment of Biofuels and Synthetic Fuels as Substitutions of Conventional Diesel and Jet Fuels2008Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today, a majority of the world’s energy need is supplied through sources that are finite and, at the current usage rates, will be consumed shortly. The high energy demand and pollution problems caused by the widespread use of fossil fuels make it increasingly necessary to develop renewable energy sources of limitless duration with smaller environmental impact than the traditional energy sources.

    Three fuels – rapeseed methyl ester (RME), Fischer-Tropsch (FT) diesel and FT jet fuel – derived from biomass, coal or gas were evaluated in this project. The fuel properties evaluated are in most cases listed in standards, often with recommendations, developed for biodiesel, petroleum diesel and jet fuel.

    Biodiesel is monoalkyl esters, e.g. RME, produced by transesterification of triglycerides in vegetable oil and an alcohol to esters and glycerin. This produce a fuel that is suitable as a direct substitution for petroleum diesel. Biodiesel may be used in pure form or in a blend with petrodiesel. Oxidative degradation and weak low temperature performance of biodiesel are properties of concern when substituting petrodiesel with biodiesel, as was shown in this project. The experiments show that oxidative stability can be improved with a synthetic antioxidant, e.g. butylated hydroxytoluene (BHT).

    The FT process converts syngas (a mixture of hydrogen and carbon monoxide) to a range of hydrocarbons. Syngas can be generated from a variety of carbon sources, e.g. coal, natural gas and biomass. The high-temperature (300-350 °C) FT process with iron-based catalysts is used for the production of gasoline and linear low molecular mass olefins (alkenes). The lowtemperature (200-240 °C) FT process with either iron or cobalt catalysts is used for the production of high molecular mass linear waxes. By applying various downstream processes, fuels suitable for substitution of petrodiesel and conventional jet fuel can be obtained. The FT fuels have lower densities than the conventional fuels. However, conclusions from this project are that most of the properties of FT fuels are better, or equal, than conventional petroleum fuels.

  • 12.
    Börjesson, Stefan
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology . Linköping University, Faculty of Health Sciences.
    Antibiotic Resistance in Wastewater: Methicillin-resistant Staphylococcus aureus (MRSA)and antibiotic resistance genes2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A large part of the antibiotics consumed ends up in wastewater, and in the wastewater the antibiotics may exert selective pressure for or maintain resistance among microorganisms. Antibiotic resistant bacteria and genes encoding antibiotic resistance are commonly detected in wastewater, often at higher rates and concentrations compared to surface water. Wastewater can also provide favourable conditions for the growth of a diverse bacterial community, which constitutes a basis for the selection and spread of antibiotic resistance. Therefore, wastewater treatment plants have been suggested to play a role in the dissemination and development of antibiotic resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) is a large problem worldwide as a nosocomial pathogen, but knowledge is limited about occurrence in non-clinical environments, such as wastewater, and what role wastewater plays in dissemination and development of MRSA.

     

    In this thesis we investigated the occurrence of MRSA in a full-scale wastewater treatment plant (WWTP). We also investigated the concentration of genes encoding resistance to aminoglycosides (aac(6’)-Ie+aph(2’’)), β-lactam antibiotics (mecA) and tetracyclines (tetA and tetB) in three wastewater-associated environments: (1) soil from an overland flow area treating landfill leachates, (2) biofilm from a municipal wastewater treatment plant, and (3) sludge from a hospital wastewater pipeline. In addition, concentrations of mecA, tetA and tetB were investigated over the treatment process in the WWTP. These investigations were performed to determine how the prevalence and concentration of MRSA and the antibiotic resistence genes are affected in wastewater and wastewater treatment processes over time. The occurrence of MRSA was investigated by cultivation and a commercially available real-time PCR assay. In order to determine concentrations of the genes aac(6’)-Ie+aph(2’’), mecA, tetA and tetB in wastewater we developed a LUXTM real-time PCR assay for each gene.

     

    Using cultivation and real-time PCR we could for the first time describe the occurrence of MRSA in wastewater and show that it had a stable occurrence over time in a WWTP. MRSA could mainly be detected in the early treatment steps in the WWTP, and the wastewater treatment process reduced the number and diversity of cultivated MRSA. However, our results also indicate that the treatment process selects for strains with more extensive resistance and possibly higher virulence. The isolated wastewater MRSA strains were shown to have a close genetic relationship to clinical isolates, and no specific wastewater lineages could be detected, indicating that they are a reflection of carriage in the community. Taken together, these data indicate that wastewater may be a potential reservoir for MRSA and that MRSA are more prevalent in wastewater than was previously thought.

     

    The real-time PCR assays, for aac(6’)-Ie+aph(2’’), mecA, tetA, and tetB that we developed, were shown to be sensitive, fast, and reproducible methods for detection and quantification of these genes in wastewater environments. The highest concentrations of all genes were observed in the hospital pipeline, and the lowest in the overland flow system, with tetA and aac(6´)-Ie+aph(2´´) detected in all three environments. In the full-scale WWTP, we continuously detected mecA, tetA and tetB over the treatment process and over time. In addition, it was shown that the treatment process reduces concentrations of all three genes. The data presented in this thesis also indicate that the reduction for all three genes may be connected to the removal of biomass, and in the reduction of tetA and tetB, sedimentation and precipitation appear to play an important role.

    List of papers
    1. Quantification of genes encoding resistance to aminoglycosides, β-lactams and tetracyclines in wastewater environments by real-time PCR
    Open this publication in new window or tab >>Quantification of genes encoding resistance to aminoglycosides, β-lactams and tetracyclines in wastewater environments by real-time PCR
    Show others...
    2009 (English)In: International Journal of Environmental Health Research, ISSN 0960-3123, 1-12 p.Article in journal (Refereed) Published
    Abstract [en]

    In this study real-time PCR assays, based on the LUX-technique, were developed for quantification of genes mediating resistance to aminoglycosides [aac(6 ')-Ie + aph(2 ' ')], beta-lactams (mecA), and tetracyclines (tetA and tetB), for use in wastewater environments. The developed assays were applied on DNA extracted from three wastewater-associated environments: soil from an overland flow area treating landfill leachates, biofilm from a municipal wastewater treatment plant, and sludge from a hospital wastewater pipeline. The highest concentration of all genes was observed in the hospital pipeline and the lowest in the overland flow system. TetA and aac(6 ')-Ie + aph(2 ' ') could be detected in all environments. The tetB gene was detected in the overland flow area and the hospital wastewater pipeline and mecA was detected in the wastewater treatment plant and the hospital pipeline. The developed LUX real-time PCR assays were shown to be fast and reproducible tools for detection and quantification of the four genes encoding antibiotic resistance in wastewater.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2009
    Keyword
    Water pollutants; sewage pollution; water quality; aac(6')-Ie + aph(2''); mecA; tetA; tetB; LUX™ real-time PCR
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-18293 (URN)10.1080/09603120802449593 (DOI)19370439 (PubMedID)
    Available from: 2009-05-15 Created: 2009-05-15 Last updated: 2009-05-15Bibliographically approved
    2. A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal wastewater treatment plant
    Open this publication in new window or tab >>A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal wastewater treatment plant
    2009 (English)In: Water Research, ISSN 0043-1354, Vol. 43, no 4, 925-932 p.Article in journal (Refereed) Published
    Abstract [en]

    The spread of methicillin-resistant Staphylococcus aureus (MRSA), in which the mecA gene mediates resistance, threatens the treatment of staphylococcal diseases. The aims were to determine the effect of wastewater treatment processes on mecA gene concentrations, and the prevalence of S. aureus and MRSA over time. To achieve this a municipal wastewater treatment plant was investigated for the mecA gene, S. aureus and MRSA, using real-time PCR assays. Water samples were collected monthly for one year, at eight sites in the plant, reflecting different aspects of the treatment process. The mecA gene and S. aureus could be detected throughout the year at all sampling sites. MRSA could also be detected, but mainly in the early treatment steps. The presence of MRSA was verified through cultivation from inlet water. The concentration of the mecA gene varied between months and sampling sites, but no obvious seasonal variation could be determined. The wastewater treatment process reduced the mecA gene concentration in most months. Taken together our results show that the mecA gene, S. aureus and MRSA occur over the year at all sites investigated.

    Keyword
    Methicillin-resistant, Staphylococcus aureus, mecA, LUX (TM) real-time PCR, spa Typing, Wastewater treatment plant, Seasonal study
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-17599 (URN)10.1016/j.watres.2008.11.036 (DOI)19084256 (PubMedID)
    Note
    Original Publication: Stefan Börjesson, Sara Melin, Andreas Matussek and Per-Eric Lindgren, A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal wastewater treatment plant, 2009, Water Research, (43), 4, 925-932. http://dx.doi.org/10.1016/j.watres.2008.11.036 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2009-07-09 Created: 2009-04-06 Last updated: 2009-07-09Bibliographically approved
    3. Methicillin-resistant Staphylococcus aureus (MRSA) in municipal wastewater: An uncharted threat?
    Open this publication in new window or tab >>Methicillin-resistant Staphylococcus aureus (MRSA) in municipal wastewater: An uncharted threat?
    Show others...
    (English)Manuscript (Other academic)
    Abstract [en]

    Methicillin-resistant S. aureus (MRSA) was recently detected in municipal wastewater, why there is a need for further studies to elucidate if MRSA in wastewater constitutes a health risk, and to determine how wastewater treatment processes affects MRSA. We cultivated MRSA from a full-scale wastewater treatment plant to characterise the indigenous MRSA-flora and to investigate how the wastewater treatment process affects the clonal distribution. MRSA isolates were characterised using spa typing, antibiograms, SSCmec typing and detection of Panton Valentine leukocidin (PVL) genes. We found that the wastewater MRSA-flora has a close genetic relationship to clinical isolates, but we also isolated novel spa types, primarily from the activated sludge treatment step. The number of isolates and the diversity of MRSA are reduced by the treatment process, but the process also selects for more extensive antibiotic resistant strains as well as for PVL positive strains.

    Keyword
    Staphylococcus aureus, MRSA, methicillin, β-lactam, SCCmec, spa typing, Panton Valentine leukocidin, PVL, antibiotic resistance, antibiogram
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-18295 (URN)
    Available from: 2009-05-15 Created: 2009-05-15 Last updated: 2010-01-14Bibliographically approved
    4. Genes encoding tetracycline resistance in a full-scale municipal wastewater treatment plant investigated during one year
    Open this publication in new window or tab >>Genes encoding tetracycline resistance in a full-scale municipal wastewater treatment plant investigated during one year
    (English)Manuscript (Other academic)
    Abstract [en]

    Tetracycline-resistant bacteria and genes encoding tetracycline resistance are common in anthropogenic environments. We studied how wastewater treatment affects the prevalence and concentration of two genes that encode resistance to tetracycline: tetA and tetB. Using real-time PCR we analysed wastewater samples collected monthly for one year at eight key-sites in a full-scale municipal wastewater treatment plant (WWTP). We detected tetA and tetB at each sampling site and the concentration of both genes, expressed per wastewater volume or per total-DNA, decreased over the treatment process. The reduction of tetA and tetB was partly the result of the sedimentation process. The ratio of tetA and tetB, respectively, to total DNA was lower in or after the biological processes. Taken together our data show that tetracycline resistance genes occur throughout the WWTP and that the concentrations are reduced under conventional operational strategies. However, it is not possible to conclude the eventual risk for humans with respect to resistance spreading.

    Keyword
    tetA, tetB, tetracycline, LUXTM real-time PCR, wastewater treatment plant
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-18296 (URN)
    Available from: 2009-05-15 Created: 2009-05-15 Last updated: 2010-01-14Bibliographically approved
  • 13.
    Fahlen, Elsa
    et al.
    Chalmers, Sweden .
    Trygg, Louise
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Ahlgren, Erik O
    Chalmers, Sweden .
    Assessment of absorption cooling as a district heating system strategy - A case study2012In: Energy Conversion and Management, ISSN 0196-8904, Vol. 60, no SI, 115-124 p.Article in journal (Refereed)
    Abstract [en]

    Heat load variations, daily as well as seasonal, are constraining co-generation of high-value energy products as well as excess heat utilisation. Integration of heat-driven absorption cooling (AC) technology in a district heating and cooling (DHC) system raises the district heat (DH) demand during low-demand periods and may thus contribute to a more efficient resource utilisation. In Sweden, AC expansion is a potentially interesting option since the cooling demand is rapidly increasing, albeit from low levels, and DH systems cover most of the areas with potential cooling demand. This study aims to assess the potential for cost and CO2 emission reduction due to expansion of DH-driven AC instead of electricity-driven compression cooling in the DHC system of Goteborg, characterised by a high share of low-cost excess heat sources. The DHC production is simulated on an hourly basis using the least-cost model MARTES. Despite recent advances of compression chillers, the results show potential for cost-effective CO2 emission reduction by AC expansion, which is robust with regards to the different scenarios applied of energy market prices and policies. While the effects on annual DHC system results are minor, the study illustrates that an increased cooling demand may be met by generation associated with low or even negative net CO2 emissions - as long as there is high availability of industrial excess heat in the DHC system, or if e.g. new biomass-based combined heat and power capacity is installed, due to the avoided and replaced marginal power generation.

  • 14.
    Feiz, Roozbeh
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Ammenberg, Jonas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Assessment of Feedstocks for Biogas Production, Part I: A Multi-Criteria Approach2017In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 122, 373-387 p.Article in journal (Refereed)
    Abstract [en]

    Biogas production is essentially based on organic materials and biological processes; hence it can contribute to the transition toward a biobased economy. In comparison with other biofuels, biogas is more flexible and can be produced from many different types of feedstock, including biomass containing various shares of carbohydrates, lipids and, both from primary and secondary raw materials. However, a significantly expanded biogas production is dependent on good business conditions, in turn related to societal acceptance and support. There are many factors that can make a biogas solution more or less suitable for both producers and the broader society. Among the many influencing factors, the choice of feedstocks (biomass) for producing biogas and biofertilizer is of strategic importance. But, to assess the suitability is complicated, because it is linked to many different challenges such as cost, energy balance, environmental impacts, institutional conditions, available technologies, geographical conditions, alternative and competing interest, and so on. Suitability includes aspects related to feasibility for implementation, potential for renewable energy and nutrient recycling, and resource efficiency. In this article, a multi-criteria framework is developed for assessing the suitability of producing biogas from different types of biomass (feedstocks). This framework allows learning about the limitations and opportunities for biogas development and more informed decision making, both in industry and policy. Existing, or forthcoming, biogas and biofertilizer producers who are considering altering or expanding their production systems can benefit from a better understanding of different choices of feedstock that are or can be (potentially) at their disposal; thus, identify hotspots, weak points, and possible candidates for implementation in future. The framework is reasonably comprehensive, yet it is simple enough to be used by practitioners. It could help to minimize the risk of sub-optimization or neglecting important risks or opportunities. This article, the first of two associated articles, is focused on the framework itself. The framework is applied to assess the suitability of producing biogas from “stickleback”, which is a non-edible fish in the Baltic Sea region. In the companion article (Part II), four other feedstocks are assessed, namely ley crops, straw, farmed blue mussels, and source-sorted food waste.

    This research is performed within the Biogas Research Center (BRC), which is a transdisciplinary center of excellence with the overall goal of promoting resource-efficient biogas solutions in Sweden. The BRC is funded by the Energy Agency of Sweden, Linköping University, and more than 20 partners from academia, industry, municipalities and other several public and private organizations.

  • 15.
    Ammenberg, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Feiz, Roozbeh
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Assessment of Feedstocks for Biogas Production, Part II: Results for Strategic Decision Making2017In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 122, 388-404 p.Article in journal (Refereed)
    Abstract [en]

    Biogas production is essentially based on organic materials and biological processes; hence it can contribute to the transition toward a biobased economy. Biogas is a biofuel that can contribute to a more renewable and local energy system. In comparison with other biofuels, biogas is more flexible and can be produced from many different types of feedstock, including biomass containing various shares of carbohydrates, lipids and, both from primary and secondary raw materials. However, a significantly expanded biogas production is dependent on good business conditions, in turn related to societal acceptance and support. There are many factors that can make a biogas solution more or less suitable for both producers and the broader society. Among the many influencing factors, the choice of feedstocks (biomass) for producing biogas and biofertilizer is of strategic importance. But, to assess the suitability is complicated, because it is linked to many different challenges such as cost, energy balance, environmental impacts, institutional conditions, available technologies, geographical conditions, alternative and competing interest, and so on. Suitability includes aspects related to feasibility for implementation, potential for renewable energy and nutrient recycling, and resource efficiency. In this article, a multi-criteria framework, which is proposed in a companion article (Part II), is used to assess the suitability of four types of feedstocks for producing biogas (considering Swedish conditions). The assessed feedstocks are ley crops, straw, farmed blue mussels, and source-sorted food waste. The results have synthesized and structured a lot of information, which facilitates considerably for those that want an overview and to be able to review several different areas simultaneously. Among the assessed feedstocks, biogas production from household food waste and ley is the most straightforward. For straw and farmed blue mussels, there are more obstacles to overcome including some significant barriers. For all feedstock there are challenges related to the institutional conditions. The assessment contributes to the knowledge about sustainable use of these feedstocks, and the limitations and opportunities for biogas development. It supports more informed decision making, both in industry and policy. Existing, or forthcoming, biogas and biofertilizer producers who are considering altering or expanding their production systems can benefit from a better understanding of different choices of feedstock that are or can be (potentially) at their disposal; thus, identify hotspots, weak points, and possible candidates for implementation in future. This research is performed within the Biogas Research Center (BRC), which is a transdisciplinary center of excellence with the overall goal of promoting resource-efficient biogas solutions in Sweden. The BRC is funded by the Energy Agency of Sweden, Linköping University, and more than 20 partners from academia, industry, municipalities and other several public and private organizations.

  • 16.
    Leduc, Sylvain
    et al.
    International Institute of Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Wetterlund, Elisabeth
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Dotzauer, Erik
    Mälardalen University, Västerås.
    Biofuel production in Europe - Potential from lignocellulosic waste2010In: Proceedings Venice 2010, Third International Symposium on Energy from Biomass and Waste, Venice, Italy: CISA, Environmental Sanitary Engineering Centre , 2010Conference paper (Other academic)
    Abstract [en]

    The objective of this study is to analyze the biofuel potential in Europe fromlignocellulosic waste (wood waste and paper and cardboard waste). Ethanol from fermentationand Fischer-Tropsch (FT) diesel from gasification are the two biofuels considered. As thosebiofuels are not yet commercially available, the optimal locations of the production plants haveto be determined. The analysis is carried out with a geographic explicit model that minimizes thetotal cost of the biofuel supply chain. A mixed integer linear program is used for theoptimization. The results show that ethanol production plants are selected in a majority of thestudied cases. Ethanol plants are mainly set up in areas with a high heat demand and/or highelectricity or heat price, whereas FT diesel production plants are set up in areas where the heatdemand is low all year round. A high cost for emitting CO2 as well as high transport fossil fuelprices favor the selection of FT diesel over ethanol production plants. With a CO2 cost of 100€/tCO2 applied, the biofuel production from waste can potentially meet around 4% of theEuropean transport fuel demand.

  • 17.
    Broberg, Sarah
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Lindkvist, Emma
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Biogas production supported by excess heat - A systems analysis within the food industry2015In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 91, 249-258 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this paper was to study the effects on greenhouse gases and economics when a change is made in the use of industrial organic waste from external production and use of biogas (A) to internal production and use (B). The two different system solutions are studied through a systems analysis based on an industrial case. The baseline system (A) and a modified system (B) were compared and analysed. Studies show that industrial processes considered as integrated systems, including the exchange of resources between industries, can result in competitive advantages. This study focuses on the integration of internally produced biogas from food industry waste produced by a food company and the use of excess heat. Two alternative scenarios were studied: (1) the use of available excess heat to heat the biogas digester and (2) the use of a part of the biogas produced to heat the biogas digester. This study showed that the system solution, whereby excess heat rather than biogas is used to heat the biogas digester, was both environmentally and economically advantageous. However, the valuation of biomass affects the magnitude of the emissions reduction. Implementing this synergistic concept will contribute to the reaching of European Union climate targets. (C) 2014 Elsevier Ltd. All rights reserved.

  • 18.
    Jansson, Niklas
    Linköping University, Department of Physics, Chemistry and Biology.
    Biologiska behandlingsmetoder för rening av rejektvatten från biogasproduktion2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this literature review the characteristics of two free-floating macrophytes, water hyacinth   (Eichhornia crassipes) and duckweed (Lemna sp.), and two microalgae, Chlorella and Scenedesmus, have been examined regarding their suitability as efficient nutrient removers in the treatment of wastewater with high levels of nutrients and suspended solids from a biogas plant in Loudden. The needs required for the plants to be able to grow in wastewater and the amounts of biomass they can produce have also been studied. The results show that Chlorella is capable of a very high uptake of nutrients in photobioreactors with high nutrient loadings. With an ammonia uptake maximum value at 10900mg/m2/d Chlorella outshines the other organisms in this study. The test organism that performed the closest to Chlorella in terms of nitrogen uptake was water hyacinth with an uptake about 1602mg/m2/d. One factor affecting nutrient uptake in a positive way is the growth rate. Free-floating macrophytes produce more biomass than algae do, and water hyacinth have been shown to be the most productive. It is important to conduct a regular harvest of the plants if a high production should be maintained. High quantity of biomass per unit area can inhibit the growth, and algae are more sensitive to this than the macrophytes often suffering from self-shading when the density is too high. The high level of nutrients in the wastewater prevents growth and dilution is required to achieve any growth at all. Therefore, conventional treatment methods might prove to be a better option.

  • 19.
    Faxälv, Olle
    et al.
    Linköping University, Department of Management and Engineering.
    Nyström, Olof
    Linköping University, Department of Management and Engineering.
    Biomass Briquettes in Malawi2007Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    In Malawi 2.5 % of the forest disappears each year. The use of firewood and charcoal, deriving from forest resources,

    accounts for about 99 % of the household energy demand in Malawi and is a cause to the deforestation. The Government of

    Malawi recently launched a programme called Promotion of Alternative Energy Sources Programme (PAESP) with the aim

    to reduce the use of firewood and charcoal. One of the fuels included in the programme is the biomass briquette. The aim

    with this study is to evaluate the viability of biomass briquettes as a sustainable alternative energy source to firewood and

    charcoal for households in Malawi.

    Research for the study was carried out during three months in Malawi. Visits were made to a number of briquette

    production sites to study the manufacturing methods and to collect briquette samples. The briquettes were tested using

    various methods and then compared with results for firewood and charcoal.

    At the moment various production methods are used in Malawi, with a high difference in technical complexity and cost.

    Machines produced from wood using very basic mechanics can apply similar pressure as more advanced metal pressers.

    They also seem to be better suited than those made of metal, in terms of price and availability.

    The majority of the briquette producers in Malawi use waste paper as base material. Although the paper briquettes are good,

    other raw materials will be needed if the production is supposed to be significantly increased.

    The briquettes burn well using the most common stoves in Malawi, including the commonly used charcoal stove. While

    firewood is cheaper to use than other available fuels, the briquettes seem to be able to compete with the fuel costs for

    charcoal.

  • 20.
    Ahmed, Ali
    et al.
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Uddin, Gazi Salah
    Linköping University, Department of Management and Engineering, Economics. Linköping University, Faculty of Arts and Sciences.
    Sohag, Kazi
    Institute of Climate Change, Universiti Kebangsaan, Malaysia.
    Biomass energy, technological progress and the environmental Kuznets curve: Evidence from selected European countries2016In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 90, 202-208 p.Article in journal (Refereed)
    Abstract [en]

    We examine the causal relationship between economic growth and CO2 emissions in a panel of 24 European countries from 1980 to 2010. Using an analytical framework that considers pooled mean group estimations in a dynamic heterogeneous panel setting, we show that there is an inverted U-shaped relationship between CO2 emissions and economic growth in the long run and that there is no such relationship in the short run. In particular, we find that biomass energy is insignificantly linked to CO2 emission. However, technological innovation significantly facilitates reduction of CO2 emissions in the investigated countries. Altogether, our study implies that economic growth and environmental quality can be achieved simultaneously, which opens up new insights for policy-makers for sustainable economic development via implementation of renewable energy consumption through technological innovation.

  • 21.
    Wetterlund, Elisabeth
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Söderström, Mats
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Biomass gasification in district heating systems - The effect of economic energy policies2010In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 9, 2914-2922 p.Article in journal (Refereed)
    Abstract [en]

    Biomass gasification is considered a key technology in reaching targets for renewable energy and CO2 emissions reduction. This study evaluates policy instruments affecting the profitability of biomass gasification applications integrated in a Swedish district heating (DH) system for the medium-term future (around year 2025). Two polygeneration applications based on gasification technology are considered in this paper: (1) a biorefinery plant co-producing synthetic natural gas (SNG) and district heat; (2) a combined heat and power (CHP) plant using integrated gasification combined cycle technology. Using an optimisation model we identify the levels of policy support, here assumed to be in the form of tradable certificates, required to make biofuel production competitive to biomass based electricity generation under various energy market conditions. Similarly, the tradable green electricity certificate levels necessary to make gasification based electricity generation competitive to conventional steam cycle technology, are identified. The results show that in order for investment in the SNG biorefinery to be competitive to investment in electricity production in the DH system, biofuel certificates in the range of 24-42 EUR/MWh are needed. Electricity certificates are not a prerequisite for investment in gasification based CHP to be competitive to investment in conventional steam cycle CHP, given sufficiently high electricity prices. While the required biofuel policy support is relatively insensitive to variations in capital cost, the required electricity certificates show high sensitivity to variations in investment costs. It is concluded that the large capital commitment and strong dependency on policy instruments makes it necessary that DH suppliers believe in the long-sightedness of future support policies, in order for investments in large-scale biomass gasification in DH systems to be realised.

  • 22.
    Wetterlund, Elisabeth
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Harvey, Simon
    Chalmers University of Technology.
    Biomass gasification integrated with a pulp and paper mill - the need for economic policies promoting biofuels2010In: Chemical Engineering Transactions, ISSN 1974-9791, Vol. 21, 1207-1212 p.Article in journal (Refereed)
    Abstract [en]

    In this study we analyse economic policy support for biofuels, with the aim to determine the amount of support necessary to make investments in a gasification based biorefinery producing DME (dimethyl ether) profitable for a pulp and paper mill. As a case the integrated Swedish pulp and paper mill of Billerud Karlsborg is studied, using mixed integer linear programming and different future energy market scenarios. The results show that the required support is strongly connected to the price ratio of oil to biomass, with the support ranging from 10 EUR/MWh biofuel (lower than the present tax exemption of 14 EUR/MWh) to 61 EUR/MWh. The required support is shown to be sensitive to changes of the capital cost, but not to the pulp and paper production rate of the host mill. It is concluded that strong policy instruments will be required for forest industry based biorefineries to be desirable for the future.

  • 23.
    Wetterlund, Elisabeth
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Harvey, S.
    Div. of Heat and Power Technology, Dept. of Energy and Environment, Chalmers University of Technology, Sweden.
    Biomass gasification integrated with a pulp and paper mill - The need for economic policies promoting biofuels2010In:  , 2010Conference paper (Refereed)
    Abstract [en]

    The economic policy support for biofuels was studied to determine the amount of support necessary to make investments in a gasification based biorefinery producing dimethyl ether profitable for a pulp and paper mill. The required support ranged from lower than the present tax exemption, to more than four times the exemption, depending mainly on the price relation between oil and biomass. The required support is sensitive to changes of the capital cost, but not to the pulp and paper production rate of the host mill. Thus, strong policy instruments will be required for forest industry based biorefineries to be desirable for the future. This is an abstract of a paper presented at the 19th International Congress of Chemical and Process Engineering and 7th European Congress of Chemical Engineering (Prague, Czech Republic 8/28/2010-9/1/2010).

  • 24.
    Difs, Kristina
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Wetterlund, Elisabeth
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Trygg, Louise
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Söderström, Mats
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Biomass gasification opportunities in a district heating system2010In: Biomass and Bioenergy, ISSN 0961-9534, Vol. 34, no 5, 637-651 p.Article in journal (Refereed)
    Abstract [en]

    This paper evaluates the economic effects and the potential for reduced CO2 emissions when biomass gasification applications are introduced in a Swedish district heating (DH) system. The gasification applications included in the study deliver heat to the DH network while producing renewable electricity or biofuels. Gasification applications included are: external superheater for steam from waste incineration (waste boost, WE), gas engine CHP (BIGGE), combined cycle CHP (BIGCC) and production of synthetic natural gas (SNG) for use as transportation fuel. Six scenarios are used, employing two time perspectives - short-term and medium-term - and differing in economic input data, investment options and technical system. To evaluate the economic performance an optimisation model is used to identify the most profitable alternatives regarding investments and plant operation while meeting the DH demand. This study shows that introducing biomass gasification in the DH system will lead to economic benefits for the DH supplier as well as reduce global CO2 emissions. Biomass gasification significantly increases the potential for production of high value products (electricity or SNG) in the DH system. However, which form of investment that is most profitable is shown to be highly dependent on the level of policy instruments for biofuels and renewable electricity. Biomass gasification applications can thus be interesting for DH suppliers in the future, and may be a vital measure to reach the 2020 targets for greenhouse gases and renewable energy, given continued technology development and long-term policy instruments.

  • 25.
    Ostwald, Madelene
    et al.
    Linköping University, The Tema Institute, Centre for Climate Science and Policy Research . Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Palm, Matilda
    Göteborg University.
    Ravindranath, N.H.
    IISc.
    Berndes, Göran
    Chalmers.
    Biomass potential on Indian wasteland2008In: Forest Adaptation 2008, IUFRO, SLU and FAO,2008, Umeå: FAO/SLU , 2008Conference paper (Refereed)
  • 26.
    Biswas, Rajib
    Linköping University, The Tema Institute, Department of Water and Environmental Studies.
    Biomethanation of Red Algae from the Eutrophied Baltic Sea2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the semi-enclosed Baltic Sea, excessive filamentous macro-algal biomass growth as a result of eutrophication is an increasing environmental problem. Drifting huge masses of red algae of the genera Polysiphonia, Rhodomela, and Ceramium accumulate on the open shore, up to five tones of algae per meter beach. During the aerobic decomposition of these algal bodies, large quantities of red colored effluents leak into the water what are toxic for the marine environment. In this study, feasibility of anaerobic conversion of red algae Polysiphonia, rich in nitrogen and phosphorous, was investigated. Biogas and methane potential of Polysiphonia, harvested in two different seasons [October and March], was investigated through three different batch digestion experiments and laboratory scale CSTR [continuous stirred tank reactor] at mesophilic (37oC) condition. Autoclavation [steam and heat] and ultrasound pretreatments were applied in order to enhance the biodegradation. In STR, anaerobic codigestion of algal biomass with SS [sewage sludge] was applied with a gradual increase in organic loading rate [1.5-4.0 g VS/L/day] and operated for 117 days at 20days HRT [hydraulic retention time]. Reactor digestate was analyzed four times over the period to determine the nutrients and heavy metals content. It is concluded that the methane potential of algae harvested in October is almost two-fold than that of algae harvested in March, probably due to it’s higher [more than double] nitrogen richness. An increase in biogas yield was observed upto 28% and VS reduction was increased from 37% to 45% due to autoclave pretreatment. Ultrasound pretreatment had no effect on digestion. In batch digestion, maximum methane yield 0.25 m3/kg VS added at 273oK, was obtained from algae [harvested in October] pretreated in autoclave. Codigestion of algae with SS worked well in STR with a comparatively lower OLR. At a higher OLR, methanogens were inhibited due to increased VFAs accumulation and decreased pH. A maximum biogas yield 0.49 m3/kg VS added at 310oK , was obtained from algae [harvested in October] pretreated with autoclave. The methane content of the produced biogas was 54%. Average [over a short period, day 99-107, reactor showed steady performance] maximum biogas yields from untreated algae obtained 0.44 m3/kg VSadded at 310oK and the VS reduction was calculated 32%. Digestate, to be used as a fertilizer, was found NH4-N, N, P, K, S and Na rich and only Cadmium level was above the maximal limit among the heavy metals. The sand content in algae during harvesting was considered as a factor to disrupt the operation. Codigestion of Polysiphonia algal biomass with substrate with higher C:N ratio like paper mill waste should be more appropriate to increase the methane and biogas yield. It is inconclusive whether AD process is a good method to dewater redalgae or not but large scale harvesting of algae will definitely contribute to curb eutrophication of the Baltic Sea through decreasing N and P level.

  • 27. Cimander, C
    et al.
    Mandenius, Carl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology .
    Bioprocess control from a multivariate process trajectory2004In: Bioprocess and biosystems engineering (Print), ISSN 1615-7591, Vol. 26, no 6, 401-411 p.Article in journal (Refereed)
    Abstract [en]

    A multivariate bioprocess control approach, capable of tracking a pre-set process trajectory correlated to the biomass or product concentration in the bioprocess is described. The trajectory was either a latent variable derived from multivariate statistical process monitoring (MSPC) based on partial least squares (PLS) modeling, or the absolute value of the process variable. In the control algorithm the substrate feed pump rate was calculated from on-line analyzer data. The only parameters needed were the substrate feed concentration and the substrate yield of the growth-limiting substrate. On-line near-infrared spectroscopy data were used to demonstrate the performance of the control algorithm on an Escherichia coli fed-batch cultivation for tryptophan production. The controller showed good ability to track a defined biomass trajectory during varying process dynamics. The robustness of the control was high, despite significant external disturbances on the cultivation and control parameters.

  • 28.
    Cimander, Christian
    et al.
    Novozymes Biopharma AB.
    Mandenius, Carl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biotechnology .
    Bioprocess control from a multivariate process trajectory.2004Article in journal (Refereed)
    Abstract [en]

    A multivariate bioprocess control approach, capable of tracking a pre-set process trajectory correlated to the biomass or product concentration in the bioprocess is described. The trajectory was either a latent variable derived from multivariate statistical process monitoring (MSPC) based on partial least squares (PLS) modeling, or the absolute value of the process variable. In the control algorithm the substrate feed pump rate was calculated from on-line analyzer data. The only parameters needed were the substrate feed concentration and the substrate yield of the growth-limiting substrate. On-line near-infrared spectroscopy data were used to demonstrate the performance of the control algorithm on an Escherichia coli fed-batch cultivation for tryptophan production. The controller showed good ability to track a defined biomass trajectory during varying process dynamics. The robustness of the control was high, despite significant external disturbances on the cultivation and control parameters.

  • 29.
    Johansson, Maria
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Bio-SNG as fuel in steel industry heating furnaces: integration of a biomass gasifier with a steel plant2012In: Asia Steel International Conference 2012, 2012Conference paper (Other academic)
    Abstract [en]

    Climate change, as a result of anthropogenic greenhouse gas (GHG) emissions, is of great concern for society today. Industry accounts for almost 40% of global CO2 emissions and consequently it is important that this sector investigate options to reduce its CO2 emissions. In this paper, an economic evaluation of integration of a biomass gasifier with a steel plant is performed. Synthetic natural gas (bio-SNG) from the gasifier substitutes liquefied petroleum gas as fuel in the steel plant’s heating furnaces. Eight future market scenarios are used to analyse investment opportunities to integrate production of bio-SNG with a case study steel plant. Results from the analysis show that high fossil fuel prices could make integration of a biomass gasifier and fuel conversion profitable. Moreover, profitability is highly dependent on biomass price. At current price levels, production cost for bio-SNG is 82 EUR/MWh.

  • 30.
    Johansson, Maria
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Söderström, Mats
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Bio-syngas as fuel in the steel industry's heating furnaces: a case study on feasibility and CO2 mitigation effects2011Conference paper (Other academic)
    Abstract [en]

    Today, climate change is at the top of the political agenda. The European Commission has set atarget to reduce greenhouse gas emissions by 20 % by 2020, compared to 1990 levels. The steelindustry contributes significantly to industrial CO2 emissions, and thus it is important for thissector to find options to reduce its CO2 emissions. One alternative is to substitute fossil fuelswith biomass derived fuels; a promising option is to replace LPG (Liquefied Petroleum Gas) used asfuel in heating furnaces with bio-syngas produced through the gasification of biomass. This paperis a feasibility study of the implementation of this concept at a Swedish scrap-based steel plant.The results have been obtained through a case study approach with interviews and literaturesurveys. The study shows that if a fuel gas mixture of 50 vol% bio-syngas and 50 vol% LPG would beused, the global CO2 emissions would be reduced by 5,400 tonnes/year. Moreover, a full-scale fuelsubstitution would result in reduced emissions by 68,600 tonnes/year. In the case of a partial fuelsubstitution, a 4 MWth High Temperature Agent Gasifier (HTAG) is a suitable choice while a 45 MWthindirectly heated Circulating Fluidised Bed Gasifier (CFBG) would be suitable for a full-scale fuelsubstitution. In the case of a fuel switch, the lower heating value of syngas, compared to LPG, notonly implies that a different combustion technology must be used, but also that the exhaust gasflows will be substantially larger, and consequently the exhaust gas cleaning system must bedesigned with dimensions suitable for larger flows. Excess heat from the gasifier can be used forspace heating, but if the excess heat replaces district heating from a Combined Heat and Power(CHP) plant, the global CO2 emissionsreductions would be less than if the excess heat is not recovered.

  • 31.
    Johansson, Maria
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Högskolan i Gävle.
    Bio-synthetic natural gas as fuel in steel industry reheating furnaces: A case study of economic performance and effects on global COemissions2013In: Energy, ISSN 0360-5442, Vol. 57, 699-708 p.Article in journal (Refereed)
    Abstract [en]

    Climate change is of great concern for society today. Manufacturing industries and construction account for approximately 20% of global CO2 emissions and, consequently, it is important that this sector investigate options to reduce its CO2 emissions. One option could be to substitute fossil fuels with renewable alternatives. This paper describes a case study in which four future energy market scenarios predicting 2030 were used to analyse whether it would be profitable for a steel plant to produce bio-SNG (bio-synthetic natural gas) in a biomass gasifier and to substitute LPG (liquefied petroleum gas) with bio-SNG as fuel in reheating furnaces. The effects on global CO2 emissions were analysed from a perspective in which biomass is considered a limited resource. The results from the analysis show that investment in a biomass gasifier and fuel conversion would not be profitable in any of the scenarios. Depending on the scenario, the production cost for bio-SNG ranged between 22 and 36 EUR/GJ. Fuel substitution would reduce global CO2 emission if the marginal biomass user is a producer of transportation fuel. However, if the marginal user of biomass is a coal power plant with wood co-firing, the result would be increased global CO2 emissions

  • 32.
    Von Arnold, Karin
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Ivarsson, Maria
    Botanical Institute, Göteborg University, Göteborg, Sweden.
    Öqvist , Mats
    Department of Forest Ecology, Swedish University of Agricultural Sciences, Umå, Sweden.
    Majdi, Hooshang
    Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Björk , Robert G.
    Botanical Institute, Göteborg University, Göteborg, Sweden.
    Weslien, Per
    Botanical Institute, Göteborg University, Göteborg, Sweden.
    Klemedtsson, Leif
    Botanical Institute, Göteborg University, Göteborg, Sweden.
    Can distribution of trees explain variation in nitrous oxide fluxes?2005In: Scandinavian Journal of Forest Research, ISSN 0282-7581, Vol. 20, no 6, 481-489 p.Article in journal (Refereed)
    Abstract [en]

    The impact of distance to tree stems on nitrous oxide (N2O) fluxes was examined to determine whether it is possible to improve the accuracy of flux estimates from boreal forest soils. Dark static chambers were placed along transects between pairs of trees within a Norway spruce stand and fluxes of N2O and carbon dioxide (CO2) were measured during the period 1999-2003. The groundwater table was measured on every sampling occasion along the transects. In addition, radiation transmission, potential diffusion rate and biomass of forest floor vegetation were measured once at each chamber site along one of the transects and soil samples were collected at three depths, from which pH, denitrification enzyme activity, soil moisture, organic matter, and carbon and nitrogen content were determined. There was a high level of variation in the N2O fluxes, both spatially and temporally. However, the spatial variation in the N2O fluxes within the transect could not be explained by differences in any of the measured variables. Sometimes, mainly when no major peaks occurred, N2O fluxes were significantly correlated with CO2 release. It is concluded that distance to stems cannot be used to improve the design of sampling schemes or for extrapolating flux levels to larger scales.

  • 33.
    Ostwald, Madelene
    et al.
    Linköping University, Department of Thematic Studies, Centre for Climate Science and Policy Research. Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Tiwari, Rakesh
    Indian Institute of Science, Bangalore, India.
    Pettersson, Kristina
    Murthy, Indu
    Indian Institute of Science, Bangalore, India.
    Berndes, Göran
    Chalmers University of Technology, Gothenburg, Sweden.
    Ravindranath, N.H.
    Indian Institute of Science, Bangalore, India.
    Karlson, Martin
    Linköping University, Department of Thematic Studies, Centre for Climate Science and Policy Research. Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Can India’s wasteland be used for biomass plantations?2015Report (Other (popular science, discussion, etc.))
    Abstract [en]

    How much of India’s vast wasteland can be used for growing plants such as eucalyptus and Jatropha? As land demands have increased, the sustainable use of marginal lands has become increasingly important. In India about 47 million hectares, or 15 percent of the total geographical area, is classified as wastelands. Here we assess the climate and land quality requirements of eucalyptus, a commonly used plantation tree, and Jatropha, a much-discussed biodiesel crop. We find that roughly half of the degraded lands are suitable for growing eucalyptus and/or Jatropha. 

  • 34.
    Rootzen, J M
    et al.
    Chalmers University of Technology.
    Berndes, G
    Chalmers University of Technology.
    Ravindranath, N H
    Indian Institute of Science, Bangalore, India.
    Somashekar, H I
    Indian Institute of Science, Bangalore, India.
    Murthy, I K
    Indian Institute of Science, Bangalore, India.
    Sudha, P
    Indian Institute of Science, Bangalore, India.
    Ostwald, Madelene
    Linköping University, Department of Thematic Studies, Centre for Climate Science and Policy Research. Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Göteborg University, Göteborg, Sweden.
    Carbon sequestration versus bioenergy: A case study from South India exploring the relative land-use efficiency of two options for climate change mitigation2010In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 34, no 1, 116-123 p.Article in journal (Refereed)
    Abstract [en]

    This case study has been carried out as a comparison between two different land-use strategies for climate change mitigation, with possible application within the Clean Development Mechanisms. The benefits of afforestation for carbon sequestration versus for bioenergy production are compared in the context of development planning to meet increasing domestic and agricultural demand for electricity in Hosahalli village, Karnataka, India. One option is to increase the local biomass based electricity generation, requiring an increased biomass plantation area. This option is compared with fossil based electricity generation where the area is instead used for producing wood for non-energy purposes while also sequestering carbon in the soil and standing biomass. The different options have been assessed using the PRO-COMAP model. The ranking of the different options varies depending on the system boundaries and time period. Results indicate that, in the short term (30 years) perspective, the mitigation potential of the long rotation plantation is largest, followed by the short rotation plantation delivering wood for energy. The bioenergy option is however preferred if a long-term view is taken. Short rotation forests delivering wood for short-lived non-energy products have the smallest mitigation potential, unless a large share of the wood products are used for energy purposes (replacing fossil fuels) after having served their initial purpose. If managed in a sustainable manner all of these strategies can contribute to the improvement of the social and environmental situation of the local community.

  • 35.
    Hedenas, Henrik
    et al.
    Abisko Science Research Stn.
    Olsson, Hakan
    Swedish University of Agriculture Science.
    Jonasson, Christer
    Abisko Science Research Stn.
    Bergstedt, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Ecology. Linköping University, The Institute of Technology.
    Dahlberg, Ulrika
    Royal Swedish Academic Science.
    Changes in Tree Growth, Biomass and Vegetation Over a 13-Year Period in the Swedish Sub-Arctic2011In: Ambio, ISSN 0044-7447, Vol. 40, no 6, 672-682 p.Article in journal (Refereed)
    Abstract [en]

    This study was conducted in the Swedish sub-Arctic, near Abisko, in order to assess the direction and scale of possible vegetation changes in the alpine-birch forest ecotone. We have re-surveyed shrub, tree and vegetation data at 549 plots grouped into 61 clusters. The plots were originally surveyed in 1997 and re-surveyed in 2010. Our study is unique for the area as we have quantitatively estimated a 19% increase in tree biomass mainly within the existing birch forest. We also found significant increases in the cover of two vegetation types-"birch forest-heath with mosses and "meadow with low herbs, while the cover of snowbed vegetation decreased significantly. The vegetation changes might be caused by climate, herbivory and past human impact but irrespective of the causes, the observed transition of the vegetation will have substantial effects on the mountain ecosystems.

  • 36.
    Bastviken, David
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Svensson, Teresia
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Sandén, Per
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Chlorine cycling and fates of 36Cl in terrestrial environments2013Report (Other academic)
    Abstract [en]

    Chlorine-36 (36Cl), a radioisotope of chlorine (Cl) with a half-life of 301,000 years, is present in some types of nuclear waste and is disposed in repositories for radioactive waste. As the release of 36Cl from such repositories to the near surface environment has to be taken into account it is of interest to predict possible fates of 36Cl under various conditions as a part of the safety assessments of repositories for radioactive waste. This report aims to summarize the state of the art knowledge on Cl cycling in terrestrial environments. The view on Cl cycling in terrestrial environments is changing due to recent research and it is clear that the chloride ion (Cl) is more reactive than previously believed. We group the major findings in three categories below according to the amount of data in support of the findings.

    From the result presented in this report it is evident that:

    • There is an ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems.
    • The abundance of naturally formed chlorinated organic compounds (Clorg) frequently exceeds the abundance of Cl, particularly in soils. Thereby Clorg in many cases dominates the total Cl pool.
    • This has important implications for Cl transport. When reaching surface soils Cl will not be a suitable tracer of water and will instead enter other Cl pools (Clorg and biomass) that prolong residence times in the system.
    • Cl dominates import and export from terrestrial ecosystems while Clorg and biomass Cl can dominate the standing stock Cl within terrestrial ecosystems.
    • Both Cl and Clorg pools have to be considered separately in future monitoring programs addressing Cl cycling.

    Further, there are also indications (in need of confirmation by additional studies) that:

    • There is a rapid and large uptake of Cl by organisms and an accumulation in green plant parts. A surprisingly large proportion of total catchment Cl (up to 60%) can be found in the terrestrial biomass.
    • Emissions of total volatile organohalogens could be a significant export pathway of Cl from the systems.
    • Some of the Clorg may be very persistent and resist degradation better than average organic matter. This may lead to selective preservation of some Clorg (with associated low bioavailability).
    • There is a production of Clorg in tissues of e.g. plants and animals and Cl can accumulate as
    • chlorinated fatty acids in organisms.

    Most other nevertheless important aspects are largely unknown due to lack of data. Key unknowns include:

    • The development over time of major Cl pools and fluxes. As long as such data is lacking we cannot assess net changes over time.
    • How the precesses behind chlorination, dechlorination and transport patterns in terrestrial systems are regulated and affected by environmental factors.
    • The ecological roles of the chlorine cycling in general.
    • The ecological role of the microbial chlorination in particular.
    • The chlorine cycling in aquatic environments – including Cl and Clorg pools in sediment and water, are largely missing.

    Given the limited present information available, and particularly the lack of data with a temporal dimension and the lack of process understanding, predictive models are challenging. We also summarize currently available methods to study Cl in the environment.

  • 37.
    Leduc, Sylvain
    et al.
    International Institute of Applied Systems Analysis, Laxenburg, Austria.
    Wetterlund, Elisabeth
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Dotzauer, Erik
    Mälardalen University, Västerås.
    Kindermann, Georg
    International Institute of Applied Systems Analysis, Laxenburg, Austria.
    CHP or biofuel production in Europe?2012In: Energy Procedia, ISSN 1876-6102, Vol. 20, 40-49 p.Article in journal (Refereed)
    Abstract [en]

    In this study, the opportunity to invest in combined heat and power (CHP) plants and second-generation biofuel production plants in Europe is investigated. To determine the number and type of production plants, a mixed integer linear model is used, based on minimization of the total cost of the whole supply chain. Different policy scenarios are studied with varying values of carbon cost and biofuel support. The study focuses on the type of technology to invest in and the CO2 emission substitution potential, at constant energy prices. The CHP plants and the biofuel production plants are competing for the same feedstock (forest biomass), which is available in limited quantities. The results show that CHP plants are preferred over biofuel production plants at high carbon costs (over 50 EUR/tCO2) and low biofuel support (below 10 EUR/GJ), whereas more biofuel production plants would be set up at high biofuel support (over 15 EUR/GJ), irrespective of the carbon cost. Regarding the CO2 emission substitution potential, the highest potential can be reached at a high carbon cost and low biofuel support. It is concluded that there is a potential conflict of interest between policies promoting increased use of biofuels, and policies aiming at decreased CO2 emissions.

  • 38.
    Setzer, Malin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Jonsson, T.
    Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden.
    Climate effects on an endangered stock of great Arctic charrManuscript (preprint) (Other academic)
    Abstract [en]

    Climate affects species in many different ways and climate change represent an important and increasing threat to single populations as well as the structure and functioning of entire ecosystems. Studies have indicated that water temperature may affect plankton spring biomass abundance in temperate lakes but does not seem to have much effect on the timing of plankton peak abundance. If plankton peak abundance is not significantly affected by water temperature, while the development time of eggs and fry is, and thus the predicted time of strong demand for food, there is a strong possibility for a trophic mismatch effect. Our data and analysis show that this indeed seems to be the case for great Arctic charr in Lake Vättern. The date when the yolk sac is predicted to be consumed is positively correlated with the standardized catches of great Arctic charr six years later. This suggest that warm winters, which result in early hatching of eggs and early date for when the yolk sac is consumed, affect survival of fry and subsequent recruitment to older size classes negatively. This leads to lower than expected catches a few years later. In addition, we also show that ice winters have a positive effect on Arctic charr with a time lag of 3-4 years and that this effect increase with the duration of the ice-cover. These effects are probably not due to trophic mismatch effects. However, all these effects are the result of a changing climate and when combined these effects of increasing water temperature, decreasing frequency and duration of ice winters are predicted to affect the stock of great Arctic charr negatively.

  • 39.
    Wiréhn, Lotten
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, The Tema Institute, Centre for Climate Science and Policy Research . Linköping University, Faculty of Arts and Sciences.
    Climate Suitable Energy Crops and Biomass Energy Potentials: Assessment of the Current and Future Prospects in Estonia2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Development of biomass energy plantations is one approach to mitigate and adapt to climate change and the energy challenges related to it; however, climate change will affect the climate conditions and in turn the selection of crops and trees suitable for renewable energy sources. In Estonia, electricity is mainly based on oil shale but since their integration in the European Union they are required to increase the share of energy from renewable sources. In this study, the possible changes of suitable species are assessed by examining the current and the future prospects and potentials with biomass energy derived from energy plantations in Estonia, taking climate change into consideration. The biomass energy potentials for the species that are climate suitable in current and future time are manually estimated, using a case study approach when determining the yields. The study result suggests that biomass energy from crops and trees have great development possibilities and that climate is not a key limitation for the selection of suitable species; in addition, the energy crops and trees appear to suit the future climate conditions better than the current. The results indicate that the established national target of 25% of energy from renewable sources in gross final consumption of energy by 2020 could be achieved to a large extent by putting energy plantations into practice.

  • 40.
    Meier, Marcus
    et al.
    SMHI, Sweden.
    Andersson, Helen
    SMHI, Sweden.
    Arheimer, Berit
    SMHI, Sweden.
    Blenckner, Thorsten
    Stockholm University, Sweden.
    Chubarenko, Boris
    Russian Academy of Sciences, Russia.
    Donnelly, Chantal
    SMHI, Sweden.
    Eilola, Kari
    SMHI, Sweden.
    Gustafsson, Bo
    Stockholm University, Sweden.
    Hansson, Anders
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Thematic Studies, Centre for Climate Science and Policy Research.
    Höglund, Anders
    SMHI, Sweden.
    Kuznetsov, Ivan
    SMHI, Sweden.
    MacKenzie, Brian
    Technical University of Denmark, Denmark.
    Müller-Karulis, Bärbel
    Stockholm University.
    Neumann, Thomas
    Leibniz-Institut fur Ostseeforschung, Germany.
    Niiranen, Susa
    Stockholm University, Sweden.
    Piwowarczyk, Joanna
    Polish Academy of Sciences, Poland.
    Raudsepp, Urmas
    Tallinn University of Technology, Estonia.
    Reckermann, Marcus
    International BALTEX Secretariat, Germany.
    Ruoho-Airola, Tuija
    Finnish Meteorological Institute, Finland.
    Savchuk, Oleg
    Stockholm University, Sweden.
    Schenk, Fredrik
    Institute for Coastal Research, Germany.
    Schimanke, Semjon
    SMHI, Sweden.
    Väli, Germo
    SMHI, Sweden.
    Weslawski, Jan-Marcin
    Polish Academy of Sciences, Poland.
    Zorita, Eduardo
    Institute for Coastal Research, Germany.
    Comparing reconstructed past variations and future projections of the Baltic Sea ecosystem: First results from multi-model ensemble simulations2012In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 7, no 3, 034005- p.Article in journal (Refereed)
    Abstract [en]

    Multi-model ensemble simulations for the marine biogeochemistry and food web of the Baltic Sea were performed for the period 1850–2098, and projected changes in the future climate were compared with the past climate environment. For the past period 1850–2006, atmospheric, hydrological and nutrient forcings were reconstructed, based on historical measurements. For the future period 1961–2098, scenario simulations were driven by regionalized global general circulation model (GCM) data and forced by various future greenhouse gas emission and air- and riverborne nutrient load scenarios (ranging from a pessimistic 'business-as-usual' to the most optimistic case). To estimate uncertainties, different models for the various parts of the Earth system were applied. Assuming the IPCC greenhouse gas emission scenarios A1B or A2, we found that water temperatures at the end of this century may be higher and salinities and oxygen concentrations may be lower than ever measured since 1850. There is also a tendency of increased eutrophication in the future, depending on the nutrient load scenario. Although cod biomass is mainly controlled by fishing mortality, climate change together with eutrophication may result in a biomass decline during the latter part of this century, even when combined with lower fishing pressure. Despite considerable shortcomings of state-of-the-art models, this study suggests that the future Baltic Sea ecosystem may unprecedentedly change compared to the past 150 yr. As stakeholders today pay only little attention to adaptation and mitigation strategies, more information is needed to raise public awareness of the possible impacts of climate change on marine ecosystems.

  • 41.
    Holmgren, Kristina
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Henning, Dag
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Comparison between material and energy recovery of municipal waste from an energy perspective: A study of two Swedish municipalities2004In: Resources, Conservation and Recycling, ISSN 0921-3449, Vol. 43, no 1, 51-73 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to compare material recovery to waste incineration with energy recovery from the criteria of energy efficiency. Material recovery saves virgin material and also energy since production processes using recovered material are less energy intensive than processes using virgin material, whereas energy recovery saves other fuels that differ among various energy systems. Optimisations are made for the district heating systems in two Swedish municipalities, showing that it is profitable for the energy utilities in the municipalities to invest in plants using waste as a fuel for electricity and heat production. The fuels replaced by the waste differ between the municipalities. For one it is mostly wood chips, and for the other, a lot of biomass is replaced, but the largest saving is in oil. Energy savings by material recycling of the waste are calculated. Non-combustible waste, such as metals and glass save energy in various extensions when material recycled, but give no heat contribution when incinerated. It is more complicated to compare material and energy recovery of combustible waste fractions, such as cardboard, paper, plastics and biodegradable waste since they can be recycled in both fashions. For these fractions it is important to consider the configuration of the energy system. The conclusions from the two municipalities are that even if there is a district heating system able to utilise the heat, from the energy-efficiency view point; paper and hard plastics should preferably be material recovered, whereas cardboard and biodegradable waste is more suited for energy recovery through waste incineration. These calculations are done with the assumption that biomass should be regarded as a limited resource and when saved eventually eliminates fossile fuel combustion in other facilities.

  • 42. Axelsson, Björn
    et al.
    Gärdefors, Dag
    Lohm, Ulrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Persson, Tryggve
    Tenow, Olle
    Wallin, Lars
    Components of variance and the cost of a sampling programme concerning biomass of hazel (Corylus avellana L.) available to leaf-eating insects1970In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 21, 203-207 p.Article in journal (Refereed)
  • 43.
    Ersson, Carolina
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology.
    Conditions for resource-efficient production of biofuels for transport in Sweden2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Transportation has continued to increase worldwide and fossil-fuel dependency is strong which leads to a number of problems, e.g. increased emissions of green-house gases (GHG) and risks related to energy security. Biofuels have until now been one of the few renewable alternatives which have been able to replace fossil fuels on a large scale. The biofuel share in relation to the total use of fuel in the transportation sector is still small, but in many places in the world political targets are set to increase the share of renewable fuels, of which biofuels are supposed to be an important part. Within the European Union targets for renewable energy have been set, including within the transportation sector, where 10% shall come from renewable sources by 2020 according to the EU Renewable Energy Directive (EU RES). Biofuels also need to fulfill the sustainability criteria in the EU RES, to be regarded as renewable. Depending on how biofuels are produced their resource efficiency varies, and the differences in environmental and economic performance can for instance be significant.

    The aim of this thesis is to describe and analyze conditions for a development towards increased and more resource-efficient production of biofuels in Sweden. The conditions have been studied from a regional resource perspective and from a biofuel producer perspective since it has been assumed that the producers are in possession of important knowledge, and potentially will play an important role in future biofuel development. The concept of resource efficiency used in this thesis includes an environmental and economic perspective as well as an overall societal dimension to some extent. The region of Östergötland in Sweden was used for the assessment of the resourcefocused biofuel potential for the year 2030, where two scenarios based on assessments regarding socio-technical development in relation to regional resources were used. The scenarios were based on semi-structured interviews with biofuel actors, literature studies and information from experts in the field. In the EXPAN (Expansion) scenario a continued development in line with the current one was assumed, but also an increased availability of feedstock primarily within the agricultural and waste sectors (also including byproducts from industry) for biofuel production. In the INNTEK (Innovation and Technology development) scenario greater technological progress was assumed to also enable the use of some unconventional feedstock besides increased available arable land and improved collection/availability of certain feedstock. Biomass feedstock from four categories was included in the potential: waste, agriculture, forestry and aquatic environments. One important feedstock which was not included in this study, but which is often included in studies of potential, is lignocellulosic material from the forest. This choice was also supported by the regional actors who judged it as less probable that there will be any large-scale use of such feedstock for biofuels in this region within the given timeframe. Regarding arable land available for biofuel production a share of 30% was assumed at maximum in the region, of which 15% is already used for cereal production for ethanol fuel. On these additional 15% assumed to be available for biofuel production year 2030, ley cropping for production of biogas was assumed in this study. Aquatic biomass is often not included in biofuel potentials. Here, algae were assumed to be a potentially interesting substrate for biogas production since harvesting algae in for instance the Baltic Sea could be seen as a multifunctional measure, i.e., contributing additional environmental benefits such as reducing eutrophication. Based on the assumption that the energy need in the transportation sector will be the same in 2030 as in 2010, up to 30% could be substituted with biofuels in the EXPAN scenario and up to 50% in the INNTEK scenario, without seriously conflicting with other interests such as food or feed production. In the study of potential, production systems for biogas production were   prioritized since such systems were judged to have a large potential for resource efficiency. This is because they have a big capacity to utilize by-products and waste as feedstock, and also because they can contribute to closing the loops of plant nutrients, seen as an important goal in society, if the digestate is returned to arable land.

    The utilization of by-products and waste however in many cases requires cooperation between different actors in society. Within the research field of industrial symbiosis, cooperation regarding material and energy flows is studied from different perspectives, e.g. how such cooperation between actors evolves and to what extent such cooperation can contribute to improving the environmental and economic performance of systems. Both these perspectives are interesting in relation to biofuels since production often involves a large number of energy- and material flows at the same time as resource efficiency is important. How the producers organize the production when it comes to feedstock, energy, by-products and products and what influences this is therefore interesting to study. In this thesis four biofuel producers of three different biofuels (ethanol, biodiesel and biogas) on the Swedish market were studied, focusing on how they organize their biofuel production in terms of e.g. their material and energy flows, and how they intend to organize it in the future. The study is based on semi-structured interviews with the biofuel producers as well as literature studies. In all the cases, a number of areas of material and energy flow cooperation were identified and it could also be concluded that there had been some change regarding these patterns over time. Looking into the future a clear change of strategy was identified in the ethanol case and partly also in the biodiesel case where a development towards improved valorisation and differentiation of by-product flows was foreseen. If such a “biorefinery” strategy is realized, it can potentially improve the economic viability and resource efficiency in these biofuel producers. In the biogas cases, instead a strategy to lower the costs for feedstock through the use of lower quality feedstock was identified. This strategy also has a potential to increase economic viability and improve the resource efficiency. However, the success of this strategy is to a large extent dependent on how the off-set of the biofertilizer can be arranged regarding the economic challenges that the biogas producers’ experience, and yet no strategy for implementation regarding this was identified. The EU Renewable Energy Directive was mentioned in relation to most cooperation projects and therefore regarded as an important critical factor. All of the studied companies also struggle to be competitive, for which reason the importance of the direct economic aspects of cooperation seems to increase.

    List of papers
    1. Biofuels for transportation in 2030: feedstock and production plants in a Swedish county
    Open this publication in new window or tab >>Biofuels for transportation in 2030: feedstock and production plants in a Swedish county
    2013 (English)In: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277, Vol. 4, no 4, 379-395 p.Article in journal (Refereed) Published
    Abstract [en]

    Background: This paper gives insight into whether biofuels for road transport can play an important role in a Swedish county in the year 2030, and contributes to knowledge on how to perform similar studies.

    Methodology: A resource-focused assessment, including feedstock from the waste sector, agricultural sector, forestry sector and aquatic environments, partially considering technological and economic constraints.

    Results: Two scenarios were used indicating that biofuels could cover almost 30 and 50%, respectively, of total energy demand for road transport.

    Conclusion: Without compromising food security, this study suggests that it is possible to significantly increase biofuel production, and to do this as an integrated part of existing society, thereby also contributing to positive societal synergies.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-102371 (URN)10.4155/bfs.13.23 (DOI)
    Available from: 2013-12-09 Created: 2013-12-09 Last updated: 2015-09-21
    2. Connectedness and its dynamics in the Swedish biofuels for transport industry
    Open this publication in new window or tab >>Connectedness and its dynamics in the Swedish biofuels for transport industry
    2015 (English)In: Progress in Industrial Ecology, An International Journal, ISSN 1476-8917, E-ISSN 1478-8764, Vol. 9, no 3, 269-295 p.Article in journal (Refereed) Published
    Abstract [en]

    Connectedness through cooperation with other sectors regarding feedstock, energy, products and by-products is important for environmental performance of industrial production. The aim of this study is to provide a better understanding of the level of connectedness in the Swedish biofuels for transport industry, involving producers of ethanol, biogas and biodiesel. In interviews, the CEOs of four important companies provided information about current strategies, historic and planned development. The production systems are dynamic and have changed significantly over time, including material and energy exchanges between traditionally separate industries. Interesting development was noted where revised business strategies have led to changed cooperation structures and thus altered material and energy flows. Fuel and raw material prices are very influential and all of the respondents said that political decisions to a large extent affect their competitiveness and emphasised the importance of clear long-term institutional conditions, ironically very much in contrast to the current situation within EU and Sweden.

    Place, publisher, year, edition, pages
    InderScience Publishers, 2015
    Keyword
    biofuels, biogas, ethanol, biodiesel, industrial ecology and symbiosis, synergies, material and energy flows, connectedness, resource efficiency
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-123223 (URN)10.1504/PIE.2015.073416 (DOI)
    Funder
    Swedish Energy Agency
    Note

    At the time for thesis presentation publication was in status: Manuscript

    Available from: 2015-12-08 Created: 2015-12-08 Last updated: 2016-12-28Bibliographically approved
  • 44.
    Kumar Das, Supriyo
    et al.
    Presidency University, India.
    Routh, Joyanto
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Roychoudhury, Alakendra N.
    Stellenbosch University, South Africa.
    Veldhuis, Marcel J. W.
    Marine Ecoanalyt, Netherlands.
    Ismail, Hassan E.
    Department Environm Affairs Oceans and Coasts, South Africa.
    Connecting pigment composition and dissolved trace elements to phytoplankton population in the southern Benguela Upwelling zone (St. Helena Bay)2017In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 176, 13-23 p.Article in journal (Refereed)
    Abstract [en]

    Rich in upwelled nutrients, the Southern Benguela is one of the most productive ecosystems in the world ocean. However, despite its ecological significance the role of trace elements influencing phytoplankton population in the Southern Benguela Upwelling System (SBUS) has not been thoroughly investigated. Here, we report pigment composition, macronutrients (nitrate, phosphate and silicate) and concentrations of dissolved Cd, Co, Fe and Zn during late austral summer and winter seasons in 2004 to understand the relationship between the selected trace elements and phytoplankton biomass in St. Helena Bay (SHB), which falls within the southern boundary of the SBUS. Chlorophyll a concentrations indicate higher phytoplankton biomass associated with high primary production during late summer in SHB where high diatom population is inferred from the presence of fucoxanthin. Diminished phytoplankton biomass and a shift from diatoms to dinoflagellates as the dominant phytoplankton taxa are indicated by diagnostic pigments during late winter. Dissolved trace elements (Cd, Co and Zn) and macronutrients play a significant role in phytoplankton biomass, and their distribution is affected by biological uptake and export of trace elements. Continuous uptake of Zn by diatoms may cause an onset of Zn depletion leading to a period of extended diatom proliferation during late summer. Furthermore, the transition from diatom to dinoflagellate dominated phytoplankton population is most likely facilitated by depletion of trace elements (Cd and Co) in the water column.

  • 45.
    Gudasz, Cristian
    et al.
    Uppsala University.
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Premke, Katrin
    Uppsala University.
    Steger, Kristin
    Uppsala University.
    Tranvik, Lars J.
    Uppsala University.
    Constrained microbial processing of allochthonous organic carbon in boreal lake sediments2012In: Limnology and Oceanography, ISSN 0024-3590, Vol. 57, no 1, 163-175 p.Article in journal (Refereed)
    Abstract [en]

    We investigated sediment bacterial metabolism in eight lakes with different inputs of allochthonous and autochthonous organic carbon in south-central Sweden. Sediment bacterial production, mineralization, and biomass were measured seasonally and along a lake depth gradient in lakes with different water and sediment characteristics. Sediment bacterial metabolism was primarily controlled by temperature but also by the quality and origin of organic carbon. Metabolism was positively correlated to measures of autochthonous influence on the sediment organic carbon, but did not show a similar increase with increasing input of allochthonous organic carbon. Hence, in contrast to what is currently known for the water column, increasing terrestrial organic carbon influence does not result in enhanced sediment bacterial metabolism. The role of allochthonous organic carbon as the main driver of sediment bacterial metabolism suggested so far is contrary to our findings. Meio- and macrobenthic invertebrate biomass were, at most, weakly correlated to bacterial metabolism and biomass, suggesting limited control of sediment bacteria by grazing. Bacterial metabolism in boreal lake sediments is constrained by low temperatures and by the recalcitrant nature of the dominant organic carbon, resulting in sediments being an effective sink of organic carbon.

  • 46.
    Gustavsson, Robert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Lukasser, Cornelia
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Mandenius, Carl-Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biotechnology. Linköping University, The Institute of Technology.
    Control of specific carbon dioxide production in a fed-batch culture producing recombinant protein using a soft sensor2015In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, Vol. 200, 44-51 p.Article in journal (Refereed)
    Abstract [en]

    The feeding of a fed-batch cultivation producing recombinant protein was controlled by a soft sensor setup. It was assumed that the control approach could be based on the cells production of carbon dioxide and that this parameter indicates the metabolic state occurring at induced protein expression. The soft sensor used the on-line signals from a carbon dioxide analyser and a near-infrared (NIR) probe for biomass to estimate the specific production rate (q(CO2)). Control experiments were carried out with various q(CO2) set-points where we observe that the feeding of nutrients to the culture could easily be controlled and resulted in a decreased variability compared to uncontrolled cultivations. We therefore suggest that this control approach could serve as an alternative to other commonly applied methods such as controlling the cells overflow metabolism of acetate or the cells specific growth rate. However, further studies of the internal metabolic fluxes of CO2 during protein expression would be recommended for a more precise characterization of the relationship between q(CO2) and protein expression in order to fully interpret the control behaviour.

  • 47.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Damage and Fracture Behaviours in Advanced Heat Resistant Materials During Slow Strain Rate Test at High Temperature2013Conference paper (Other academic)
    Abstract [en]

    As a renewable energy resource, biomass or biomass co-firing in coal-fired power plants with high efficiency are desired which corresponding to elevated temperature and high pressure. An upgrade of the material performance to austenitic stainless steels is therefore required in order to meet the increased demands due to the higher temperature and the more corrosive environment. These materials suffer from creep and fatigue damage during the service. In this study, these behaviours are evaluated using slow strain rate testing (SSRT) with strain rate down to 1*10-6/s at temperature up to 700°C. The influence of temperature and strain rate on strength and ductility in one austenitic stainless steel and one nickel base alloys are investigated. The damage and fracture due to the interaction between moving dislocations and precipitates are studied using electron channelling contrast imaging (ECCI) and electron backscattering diffraction (EBSD). The deformation and damage mechanisms active during SSRT are essentially the same as under creep. The influence of dynamic strain ageing (DSA) phenomena that appears in the tested temperature and strain rate regime is also discussed, DSA is intensified by increased temperature and decreased strain rate.

  • 48.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Damage and Fracture Behaviours in Aged Austentic Materials During High-Temperature Slow Strain Rate Testing2014Conference paper (Refereed)
    Abstract [en]

    Biomass power plants with high efficiency are desired as a renewable energy resource. High efficiency can be obtained by increasing temperature and pressure. An upgrade of the material performance to high temperature material is therefore required in order to meet the increased demands due to the higher temperature and the more corrosive environment. In this study, the material’s high-temperature behaviours of AISI 304 and Alloy617 under slow deformation rate are evaluated using high-temperature long-term aged specimens subjected to slow strain rate tensile testing (SSRT) with strain rates down to 10-6/s at 700°C. Both materials show decreasing stress levels and elongation to fracture when tensile deformed using low strain rate and elevated temperature. At high-temperature and low strain rates cracking in grain boundaries due to larger precipitates formed during deformation is the most common fracture mechanism.

  • 49.
    Lúcia Santoro, Ana
    et al.
    Department of Ecology, Institute of Biology, University Federal of Rio de Janeiro, Rio de Janeiro, Brazil.
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Gudasz, Cristian
    Department of Ecology and Evolution - Limnology, Uppsala University, Uppsala, Sweden.
    Tranvik, Lars
    Department of Ecology and Evolution - Limnology, Uppsala University, Uppsala, Sweden.
    Enrich-Prast, Alex
    Department of Ecology, Institute of Biology, University Federal of Rio de Janeiro, Rio de Janeiro, Brazil.
    Dark Carbon Fixation: An Important Process in Lake Sediments2013In: PLoS ONE, ISSN 1932-6203, Vol. 8, no 6Article in journal (Refereed)
    Abstract [en]

    Close to redox boundaries, dark carbon fixation by chemoautotrophic bacteria may be a large contributor to overall carbon fixation. Still, little is known about the relative importance of this process in lake systems, in spite the potentially high chemoautotrophic potential of lake sediments. We compared rates of dark carbon fixation, bacterial production and oxygen consumption in sediments from four Swedish boreal and seven tropical Brazilian lakes. Rates were highly variable and dark carbon fixation amounted up to 80% of the total heterotrophic bacterial production. The results indicate that non-photosynthetic carbon fixation can represent a substantial contribution to bacterial biomass production, especially in sediments with low organic matter content.

  • 50.
    Svensson, Bo
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Dark fermentation for hydrogen production from organic wastes2005In: Biofuels for fuel cells: renewable energy from biomass fermentation / [ed] Lens, Piet, London: IWA Publishing , 2005, 209-220 p.Chapter in book (Other academic)
    Abstract [en]

    The increasing demand for energy and the related environmental concerns are the main drivers for the strong interest in Biomass Fermentation towards usage in Fuel Cells. The integration of Biomass Fermentation (BF) and Fuel Cells (FC) technology creates a new and interdisciplinary research area. Due to their high efficiency Fuel Cells are therefore considered as a strategic technology for future energy supply systems. The fact that biomass is a renewable source of energy in combination with the most efficient energy conversion system (FC) makes this combination unique and advantageous. This book has a clear orientation towards making products of our waste. Biofuels for Fuel Cells comes at a time when this field is rapidly developing and there is a need for a synthetising book. The holistic and multidisciplinary description of this topic, including discussion of technological, socio-economic, system analysis and policy and regulatory aspects, make this book the definitive work for this market. Biofuels for Fuel Cells will cross-link scientists of all fields concerned with Biomass Fermentation, Fuel Upgrading and Fuel Cells at European and World level.

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