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  • 1.
    Danestig, Maria
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Björn
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Stockholm CHP potential: opportunity for CO2 reductions?2007In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 35, no 9, p. 4650-4660 Article in journal (Refereed)
    Abstract [en]

    The potential for combined heat and power (CHP) generation in Stockholm is large and a total heat demand of about 10 TWh/year can be met in a renewed large district heating system. This model of the Stockholm district heating system shows that CHP generation can increase from 8% in 2004 to 15.5% of the total electricity generation in Sweden. Increased electricity costs in recent years have awakened an interest to invest in new electricity generation. Since renewable alternatives are favoured by green certificates, bio-fuelled CHP is most profitable at low electricity prices. Since heat demand in the district heating network sets the limit for possible electricity generation, a CHP alternative with a high electricity to heat ratio will be more profitable at when electricity prices are high. The efficient energy use in CHP has the potential to contribute to reductions in carbon dioxide emissions in Europe, when they are required and the European electricity market is working perfectly. The potential in Stockholm exceeds Sweden's undertakings under the Kyoto protocol and national reduction goals.

  • 2.
    Gebremedhin, Alemayehu
    Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, The Institute of Technology.
    The impact of a widened energy system boundary on cost effectiveness2000Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This study describes the impact of widened system boundaries in the choice of heat generating plants, the total cost of the defined energy system and the use of combined heat and power (CHP) production plants. The economic and environmental benefits of co­ operation between public utilities and industries and the importance of enlarged system boundaries are shown in the different case-studies.

    The analysis was based on computer modelling of municipal and industrial energy systems. A user-friendly graphical interface program based on the linear programming model, MODEST, was developed as part of this study. The majority of the case-studies presented in this thesis were then performed with this application program.

    The various case-studies clearly indicate the cost reduction potential of co-operation. Both utilities and heat supplying industries benefit from this co-operation concerning heat supply. The cost saving potentials change from one case to another and depend on several factors.

    New plants within a sub-system appear to be attractive when this system is connected with other sub-systems within the extended system boundaries. In general, we can say that an extended system boundary leads normally to reduced total costs, more rational utilisation of plants, increased heat and electricity generation through the CHP plant and declining use of fossil fuels.

    The net present value of the maximum allowable investment cost for district-heating pipeline connections is roughly estimated when the cost for connection is not given or known. This cost can be used as a guideline to indicate whether connections should be considered or not.

  • 3.
    Gebremedhin, Alemayehu
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Energy Systems.
    The role of a paper mill in a merged district heating system2003In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 23, no 6, p. 769-778Article in journal (Refereed)
    Abstract [en]

    Recent studies have shown that there is great potential benefit in utilities collaborating around heat supply. Analyses based on an extended system boundary clarify the advantage of mutual co-operation in the district heating markets. The purpose of this study is to show how far a local paper mill affects the degree of co-operation between two utilities. Current and future electricity prices and existing and potential plants are considered in the different scenarios in the study. The results in all the scenarios clearly show that the paper mill plays an active role in an integrated heat supply system. The scenario where co-operation, new plants and future electricity prices are considered, gives the lowest total system cost. A new back pressure turbine with a higher electricity-to-heat output ratio in combination with high trade prices promotes increased electricity and heat generation in the co-generation plant. The proportion of combined heat and power in district heating would increase if co-operation between the players were encouraged. ⌐ 2003 Elsevier Science Ltd. All rights reserved.

  • 4.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Akkerman, H.
    Ottosson, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering.
    Energy System Analysis: Optimization of the Karlshamn Energy System, in the KEES Project2001Other (Other (popular science, discussion, etc.))
    Abstract [en]

        

  • 5.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Energy Systems.
    Carlson, A.
    Optimisation of merged district - heating systems - Benefits of co - operaion in the light of externality costs2002In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 73, no 3-4, p. 223-235Article in journal (Refereed)
    Abstract [en]

    Studies have shown that separate actors can benefit from co-operation around heat supply. Such co-operation, for example, might be between an industry selling waste heat to a districtheating system or two district-heating systems interconnecting their respective systems. Cooperation could also be expected to reduce the environmental impacts of the energy systems by choosing the plants with the lowest emissions. It is widely accepted that the production of heat and electricity causes damage to the environment. This damage often imposes a cost on society, but not on company responsible. In general, using a broader system perspective when analysing local energy systems results in a lower total cost, more e.cient use of plants and a greater potential for producing electricity in combined heat-and-power (CHP) plants. Internalising the externality costs in the energy system model facilitates the study of what cooperation can mean for reducing emissions. This study shows that co-operation between the two systems is on the whole cost-effective, but the benefits are greater when external costs are not included in the calculation. Considering externality costs in combination with current electricity prices would lead to a higher system cost, but the quantity of emission gases will be lower. If, on the other hand, the calculation is made taking externality costs and corresponding adjusted electricity prices (the adjustment being necessary to compensate for the additional cost due to externality costs) into consideration, the quantities of emission gases will rise because more heat-and-power will be generated by one of the CHP plants. © 2002 Elsevier Science Ltd. All rights reserved.

  • 6.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Glad, Wiktoria
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute, Technology and Social Change.
    Gustafsson, Stig-Inge
    Linköping University, Department of Mechanical Engineering.
    Energianalys Solna. Forskningsrapport inom programmet Uthållig kommun.2004Report (Other academic)
  • 7.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Gustafsson, Stig-Inge
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Glad, Wictoria
    Tema T Linköpings Universitet.
    Energisystemanalys Solna2004Report (Other academic)
  • 8.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Henning, Dag
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Palm, Jenny
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute, Technology and Social Change.
    Energianalys Vingåker2006Report (Other academic)
  • 9.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Björn
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Bjornfot , K
    Shell Raffinaderi AB.
    Sustainable energy system - A case study from Chile2009In: RENEWABLE ENERGY, ISSN 0960-1481 , Vol. 34, no 5, p. 1241-1244Article in journal (Refereed)
    Abstract [en]

    This paper presents some of the results of a power system analysis for Chile. The two major Chilean electric systems are roughly modelled and optimized using a linear programming method with the option to integrate renewable energy sources like wind power, solar power, mini-hydropower and biomass-fired power and also "municipal waste". A total of four different scenarios are outlined: reference system, new production units, gas and coal price variations and a policy measure to encourage power production based on renewable energy. The objective of the scenarios was to illustrate under what conditions integration of the different energy sources in the existing production system is possible. The study shows that even under current conditions, mini-hydro and waste to energy plants are economically viable. Wind power might be interesting alternatives if policy instrument measures are applied. On the other hand, it is hard for the other energy sources to enter the system even when higher price levels of gas and coal are applied. The system is more sensitive to coal price increases than to gas price increases and this mainly encourages CO2 emission reduction.

  • 10.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Moshfegh, Bahram
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Modelling and optimization of district heating and industrial energy system - An approach to a locally deregulated heat market2004In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 28, no 5, p. 411-422Article in journal (Refereed)
    Abstract [en]

    Regions with densely concentration of industries and district heating systems (DHS) could be interesting study object from the light of an integrated heat market on local basis. System analysis with a widened system boundary could be used as an approach to evaluate the benefit of an integrated heat supply system. In this study, an energy system model consisting of totally seven different participants is designed and the optimization results of the system analysis are presented. With applied data and assumptions, the study shows that a significant amount of the heat demand within two sub-systems can be covered by heat supply from the heat market (the entire heat comes from two industries). Shadow prices, which can be used for heat pricing, indicate the advantage of an integrated system. The system cost reduction through integration and the availability of several actors with diverse energy supply system, makes the region under study an interesting area to prove a locally deregulated heat market.

  • 11.
    Gebremedhin, Alemayehu
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Zinko, Heimo
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Avoiding high return temperatures with absorption coolers in district heating systems2004In: 9th International Symposium on district heating and cooling,2004, 2004, p. 191-Conference paper (Refereed)
  • 12.
    Henning, Dag
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Danestig, Maria
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Holmgren, Kristina
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Modelling the impact of policy instruments on district heating operations: experiences from Sweden2006In: 10th International Symposium on District Heating and Cooling, Hanover, Germany, 2006Conference paper (Refereed)
    Abstract [en]

    Emission allowances aim at reducing carbon dioxide emissions in the European Union. Feed-in tariffs and green certificates increase renewable electricity generation in some countries. Undesired energy carriers, such as fossil fuels, can be taxed to decrease consumption. In Sweden, monetary policy instruments have been used for many years, which has influenced district-heating utilities’ operations and investments.

    The energy system optimisation model MODEST may help elucidating the impact of policy instruments on choices of fuels and plants. The model can minimise operation and investment costs for satisfying district heating demand, considering revenues from electricity sales and waste reception. It has been used to analyse heat and electricity production for 50 local Swedish utilities. This paper shows how some plants, systems and policy instruments have been modelled and results from some case studies. It may help analysts who face policy instruments, which probably will have a growing influence on district heating operations.

    Policy instruments should reflect external costs and induce behaviour that is beneficial from an overall viewpoint. Swedish fossil-fuel taxes hampered cogeneration during many years. Earlier, fuel input could be freely allocated to output energy forms and wood was often used for heat production and coal for electricity generation to minimise taxes. Now, lower taxes promote fossil cogeneration but green certificates make it more profitable to invest in renewable electricity generation.

    Carbon dioxide emission allowances can reduce local emissions due to districtheating and electricity production significantly at current price levels but the impact depends on allowance price. With emission trading, investment in a natural-gas-fired cogeneration plant may be beneficial for some utilities due to high electricity prices in the European electricity market, partly caused by emission allowances.

    District-heating demand can enable utilisation of resources that otherwise would be of no value. A landfill ban now increases waste incineration, which may reduce industrial waste heat utilisation and heat disposal from cogeneration plants and thereby decrease electricity production. A tax on incinerated waste may reduce the profitability of investing in waste incineration.

  • 13.
    Henning, Dag
    et al.
    Optensys Energianalys .
    Gebremedhin, Alemayehu
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Energy Systems.
    Future biofuel utilisation for small-scale heating and large-scale heat, electricity and automotive fuel production2008In: World Bioenergy 2008. Taking you from Know-how to Show-how,2008, 2008Conference paper (Refereed)
    Abstract [en]

         

  • 14.
    Henning, Dag
    et al.
    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.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Enhanced biofuel utilisation in Swedish industries, buildings and district heating2006In: the World Bioenergy 2006 Conference and exhibition on Biomass for Energy, Jönköping, Sweden, 30 may – 1 June, 2006, p. 198-203Conference paper (Refereed)
  • 15.
    Holmgren, Kristina
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Modelling a district heating system: introduction of waste incineration, policy instruments and co-operation with an industry2004In: Energy Policy, ISSN 0301-4215, Vol. 32, no 16, p. 1807-1817Article in journal (Refereed)
    Abstract [en]

    The capacity for waste incineration in Swedish municipalities is increasing due to regulations aimed at decreasing landfill with waste. This has a large impact on the municipal energy systems, since waste is an important fuel for district heating production. The object of this study is a municipality, Skövde, which is planning to build a waste incineration plant to produce electricity and heat. The municipality is also planning to extend the district heating grid to include a large industrial heat consumer. The economic effect on the energy system of these measures is analysed as well as environmental effects in terms of carbon dioxide emissions. The consequences of two different policy instruments, green electricity certificates and a tax on waste incineration, are also studied. Economic optimisations show that the advantage of co-operation with industry is twofold: lower heat production costs and a considerable reduction of carbon dioxide emissions. It is economically feasible to invest in a waste incineration plant for heat production. An important measure to lower carbon dioxide emissions is to introduce combined heat and power production on the assumption that locally produced electricity replaces electricity produced by coal condensing power.

  • 16.
    Karlsson, Magnus
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Klugman, Sofia
    Gävle University.
    Henning, Dag
    Optensys Energianal.
    Moshfegh , Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Regional energy system optimization - Potential for a regional heat market2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 4, p. 441-451Article in journal (Refereed)
    Abstract [en]

    Energy supply companies and industrial plants are likely to face new situations due to, for example, the introduction of new energy legislation, increased fuel prices and increased environmental awareness. These new prerequisites provide companies with new challenges but also new possibilities from which to benefit. Increased energy efficiency within companies and increased cooperation between different operators are two alternatives to meet the new conditions. A region characterized by a high density of energy-intensive processes is used in this study to find the economic potential of connecting three industrial plants and four energy companies, within three local district heating systems, to a regional heat market, in which different operators provide heat to a joint district heating grid. Also, different investment alternatives are studied. The results show that the economical potential for a heat market amounts to between 5 and 26 million EUR/year with payback times ranging from two to eleven years. However, the investment costs and the net benefit for the total system need to be allotted to the different operators, as they benefit economically to different extents from the introduction of a heat market. It is also shown that the emissions of CO2 from the joint system would decrease compared to separate operation of the systems. However, the valuation of CO2 emissions from electricity production is important as the difference of emitted CO2 between the accounting methods exceeds 650 kton/year for some scenarios.

  • 17.
    Palm, Jenny
    et al.
    Linköping University, Faculty of Arts and Sciences. Linköping University, The Tema Institute, Technology and Social Change.
    Gebremedhin, Alemayehu
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Energianalys Borås2005Report (Other academic)
  • 18.
    Trygg, Louise
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Karlsson, Björn G.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Resource-effective systems achieved through changes in energy supply and industrial use: the Volvo Skövde case2006In: Applied Energy, ISSN 0306-2619, Vol. 83, no 8, p. 801-818Article in journal (Refereed)
    Abstract [en]

    The result presented in this paper shows that the Volvo plant can decrease its electricity use by 44% by making the use of electricity more efficient and converting from oil and electricity to district heating for hot tap-water, space heating and cooling. The increased demand of district heating makes investing in a new planned CHP and cooperation between the Volvo plant and the local energy utility production cost fall by 46% at current unit electricity price and by 64% when calculating with a European unit electricity price and investment in an optimised CHP system instead of the planned plant. The study furthermore shows that the global emissions of the greenhouse gas carbon-dioxide will be reduced by 350% a year if the two energy-supply measures are taken and the electricity unit prices are at a European level.

  • 19.
    Tveit, Tor-Martin
    et al.
    Helsinki University of Technology.
    Savola, Tuula
    Helsinki University of Technology.
    Gebremedhin, Alemayehu
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Fogelholm , Carl-Johan
    Helsinki University of Technology.
    Multi-period MINLP model for optimising operation and structural changes to CHP plants in district heating networks with long-term thermal storage2009In: ENERGY CONVERSION AND MANAGEMENT, ISSN 0196-8904 , Vol. 50, no 3, p. 639-647Article in journal (Refereed)
    Abstract [en]

    By using thermal storages it is possible to decouple the generation of power and heat, and it can also lead to an reduction in investments, as the storage can be used to cover the peak load periods. This work presents a MINLP model that can be used for analysing new investments and the long-term operation of CHP plants in a district heating network with long-term thermal storage. The model presented in this work includes the non-linear off-design behaviour of the CHP plants as well as a generic mathematical model of the thermal storage, without the need to fix temperatures and pressure. The model is formulated in such a way that it is suitable for deterministic MINLP solvers. The model is non-convex, and subsequently global optimality cannot be guaranteed with local solvers. In order to reduce the chance of obtaining a poor local optimum compared to the global optimum, the model should be solved many times with the initial values varying randomly. It is possible to extract a lot of results from the model, for instance total annual profit, the optimal selection of process options, mass flow through the plant, and generated power from each plant. The formulation of the model makes it suitable for deterministic MINLP solvers.

  • 20.
    Zinko, Heimo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Energy Systems.
    Gebremedhin, Alemayehu
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Energy Systems.
    Klasson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Reduction of CO2 emissions in district heating areas2008In: 10th World Renewable Energy Congress WRECX,2008, 2008, p. 2675-2680Conference paper (Refereed)
  • 21.
    Zinko, Heimo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Söderberg, Sven-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Fahlén, Elsa
    Gebremedhin, Alemayehu
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Energy Systems.
    Integration av absorptionsmaskiner i fjärrvärmesystem2004Report (Other academic)
1 - 21 of 21
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