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  • 201.
    Unnikrishnan, Vishnu
    et al.
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Vesterbacka, Mark
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Alvandpour, Atila
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    VCO-based ADCs for IoT applications2016In: 2016 International Symposium on Integrated Circuits (ISIC), IEEE Press, 2016, p. 1-4Conference paper (Refereed)
    Abstract [en]

    Internet of things (IoT) benefits from fast and low cost development of technology portable re-configurable hardware. Low power consumption is desired for applications operating from harvested or limited energy. Subthreshold operation of VCO-based ADCs is investigated in this work in order to meet these challenges. A ring VCO built using NAND gates is used for reliable operation in the subthreshold region. The impact of supply scaling and PVT variations on the VCO characteristics as well as on the converter performance is studied using transistor level simulations. Some solutions are suggested towards energy efficient operation over a wide range of PVT conditions.

  • 202.
    Waldemarsson, Martin
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Energy considerations in planning slab furnaces at a steel company: A case study at SSAB2014Manuscript (preprint) (Other academic)
    Abstract [en]

    To save energy and reduce costs we suggest production planning to consider issues with clear and large impact on both usage and costs of energy. This paper investigates how the energy system interacts with the production processes early in the value chain at a steel company. A case study at one of the company’s production facilities reveals promising opportunities to achieve increased energy efficiency by considering an energy‐related approach in planning of the continuous slab furnaces and the hot rolling processes. Analysis shows that energy can be saved and costs reduced through an alternative planning approach without taking any noteworthy investment cost. Improved communication within the different parts of the organization plays also a significant part in actualizing the managerial opportunities located. Real company data provided from the case company SSAB is used and analyzed. This paper contributes with a model used for analytical calculations on how market conditions could motivate a company to select different planning approaches. This by choosing a primary and secondary slab furnace based on their energy characteristics. As such, when the opportunities are beneficial enough, the impact of energy issues on production and supply chain planning should not be neglected.

  • 203.
    Waldemarsson, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Planera massa med energi2019Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Med anledning av den senaste tidens uppvaknande kring klimatfrågans akuta läge har jakten på förnybara bränslen intensifierats. Hur och när den fossilbaserade ekonomin kommer överges åter-står att se, men mycket talar för att skogsindustrin med sina biobaserade energibärare kommer spela en fortsatt betydande roll, såväl i Sverige som i andra länder med mycket skog.

  • 204.
    Waldemarsson, Martin
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Planning production and supply chain in energy intensive process industries2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To make a difference among the energy intensive process industries, this dissertation addresses production planning and supply chain planning problems related to industrial energy management issues. The energy issue is turning more and more important from different angles, involving price as well as environmental problems due to climate change leading to political pressure on all energy users. The process industry sector is one of the largest users of energy, and thus important to analyse. Process industries are also capital intensive and operate on large and expensive process equipment, making it imperative to plan their production well in order to reach preferable capacity utilisation. Therefore this dissertation strives to locate the most important energy management issues for the long term profitability of process industries, and investigates the  symbiotic effects of including energy issues in production and supply chain planning.

    Three different studies at three case companies are carried out, analysed, and presented in five papers. The cases represent the process industry sectors: chemicals, pulp, and steel. Both qualitative case study methodologies as well as quantitative mathematical modelling and optimisation approaches have been practiced. The research questions are analysed from both an energy system and from a production process point of view, separately as well as combined. Energy is somewhat considered to be the main workforce for process industries and this dissertation exemplifies some of its most important dimensions in this context.

    Several prerequisites for putting energy management on the strategic agenda are located in a specialty chemical industry where the importance of introducing a strategic perspective on energy, the way energy is used, and the possibilities of increasing alternative revenue from utilising by- and/or co-products differently are pinpointed. Approaches for including energy issues in planning processes are also suggested in terms of a MILP model for the entire supply chain of a pulp company, including decisions on purchase and transportation of raw maerials, production allocation, energy mix, and distribution. Another example is presented based on the perspectives of economics of scale and lot sizing through economic order quantity principles in a steel company. By using real company data, energy smart approaches in planning and scheduling are developed with respect to the most important intersections between the production processes and their supporting energy system. The accumulated resource intensity and embedded energy could, and probably should, hence be more fairly  reflected in the product price. The research finally shows some possible impact with including energy issues in a production and supply chain planning model. By planning differently, production prioritisations can be done, and it is not only possible without any large investments, but also prosperous with savings on both energy and money within reach.

    To conclude, planning of production and supply chain has either a direct or an indirect impact on the energy cost-effectiveness of a company. This dissertation argues that such impact also exists in its mutual form, and is very important when the energy issues are large enough, as they often are in the energy intensive process industry sector. Decision makers should thus beware of the short end of the stick that might be  devastating in the long run, but also aware of all the possibilities that can bring success and prosperity when the future begins.

    List of papers
    1. Strategic Perspectives on Energy Management: A Case Study in the Process Industry
    Open this publication in new window or tab >>Strategic Perspectives on Energy Management: A Case Study in the Process Industry
    2013 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 104, p. 487-496Article in journal (Refereed) Published
    Abstract [en]

    It has been anticipated that energy management will gain increased interest amongst companies in a near future. Yet, even in energy-intensive companies, like process industries, energy management is seldom treated strategically. The purpose of this study is thus to investigate the necessary prerequisites for putting energy management on the strategic agenda in energy-intensive process industries. This is done by the means of a literature review and a case study, and the analysis is based on how energy management is treated from three perspectives; a strategic perspective, an energy system utilisation perspective, and an alternative revenue perspective. The case study shows, similar to other process industry companies, that the strategic importance of energy management, to a large extent, is neglected. The research also indicates necessary prerequisites, for each perspective, for highlighting the strategic importance of energy management for a typical company in the process industry sector.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Energy management, energy-intensive production systems, energy efficiency, energy planning, specialty chemicals, case study
    National Category
    Production Engineering, Human Work Science and Ergonomics Business Administration
    Identifiers
    urn:nbn:se:liu:diva-84987 (URN)10.1016/j.apenergy.2012.11.027 (DOI)000316152700049 ()
    Note

    An earlier version of this paper was presented at EurOMA 2010, 6-9 June, Porto, Portugal.

    Available from: 2012-10-30 Created: 2012-10-30 Last updated: 2017-12-07
    2. Including energy in supply chain planning at a pulp company
    Open this publication in new window or tab >>Including energy in supply chain planning at a pulp company
    2013 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 1056-1065Article in journal (Refereed) Published
    Abstract [en]

    In this paper we consider integrated planning of the supply chain at a multi-site pulp company. In addition to the traditional focus on pulp products, also energy aspects are considered, both in the form of raw material and as revenue generating products. The idea is that energy intense raw materials not only gives fibre to the pulp process but also generates an energy surplus that can be used in different ways to create additional value or revenues. The planning horizon is one year and monthly time periods are considered. Decisions included in the planning are; purchase and transportation of raw materials from harvest areas to pulp mills, production allocation by dividing the production among the pulp mills, energy mix by choosing the energy input at the pulp mills, and distribution of products from mills to customer. An MILP model for the entire supply chain is proposed. A number of different scenarios including real data from the case company are analyzed and evaluated. The aim of the study is thus to investigate the effects on profitability while taking energy issues into consideration.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    supply chain optimization, energy planning, energy-intensive production systems, MILP model, process industry
    National Category
    Engineering and Technology Business Administration Production Engineering, Human Work Science and Ergonomics Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-84988 (URN)10.1016/j.apenergy.2012.12.032 (DOI)000329377800113 ()
    Note

    An earlier version of this paper was presented at ICAE 2012, 5- 8 July, Suzhou, China.

    Available from: 2012-10-30 Created: 2012-10-30 Last updated: 2017-12-07
    3. How energy price changes can affect production- and supply chain planning – A case study at a pulp company
    Open this publication in new window or tab >>How energy price changes can affect production- and supply chain planning – A case study at a pulp company
    2017 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 203, p. 15p. 333-347Article in journal (Refereed) Published
    Abstract [en]

    The process industry in general is very energy-intensive, and therefore models focusing on energy can be very important in order to reach higher profitability. In this study, an optimization model of the supply chain in a pulp company, where energy is included with respect to its revenue generating capabilities, is used. Using real company data, and through an analysis of the model’s results, we show that higher profitability can be achieved when integrating energy into the planning process. Our findings show that when energy-intensive raw materials not only provide fibre to the pulp process but also generate an energy surplus, there is room for different planning approaches in order to maximize the total profit. This paper reveals promising changes that can be made for improving the current planning process. The scenarios considered involve market changes for energy demand and price, and also alternative production opportunities. A cross-analysis compares the scenarios in order to reveal additional relations that are important to consider. Depending on a price change of energy, the model prioritizes in its selection of pulp products to produce. From this we provide guidelines on where and when to increase or decrease pulp production. The model shows that the company can increase its total profit no matter which of the included energy parameters that increase in price. The paper contributes to previous research by enhancing the usefulness of this model for not only the case company as such, but also by illustrating and describing how the approach applied can be useful for other cases within the energy intensive industry.

    Place, publisher, year, edition, pages
    Elsevier, 2017. p. 15
    Keywords
    Supply chain planning; Energy revenues; Energy-intensive production systems; Mixed Integer Linear Programming (MILP); model; Process industry
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-138731 (URN)10.1016/j.apenergy.2017.05.146 (DOI)000412379300024 ()
    Note

    The previous status of this article was Manuscript and the original title was How energy price changes can affect supply chain planningat a pulp company.

    Funding agencies: Swedish Foundation for Strategic Research (SSF)

    Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2019-09-18Bibliographically approved
    4. Energy issues in supply chain and production planning in the steel industry: A case study at SSAB
    Open this publication in new window or tab >>Energy issues in supply chain and production planning in the steel industry: A case study at SSAB
    2014 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    How can a different planning of production and supply chain increase energy efficiency and effectiveness? This descriptive and rather exploratory case study investigates these possibilities by mapping the production system and its supporting energy system at a steel company’s production site. Several possibilities for improvement in the planning processes have been located and evaluated. Our findings resulted in identifying four different improvement areas: 1) planning slab furnaces, 2) utilizing embedded heat and shortening lead times, 3) broader frame when scheduling for decreasing waste at set-ups, and 4) demandresponse opportunities related to electricity price variations. The first improvement area: planning of the slab furnaces, shows the largest potential, both in terms of energy savings and reduced costs. The second and the third improvement areas are similar to each other in terms of potential energy savings, but if the lead-time also could be decreased in the second it would be more economically beneficial than the other. Additional possibilities are found in the fourth improvement area where electricity demand response actions by rescheduling the energy-intensive production into times of low electricity price might save electricity costs. To conclude, the company could reach both higher energy efficiency and profitability simultaneously, by utilizing the energy- and the production systems combined in a more efficient and effective way.

    Keywords
    Production planning, supply chain planning, energy efficiency, energy system, case study, steel industry
    National Category
    Engineering and Technology Economics and Business Business Administration Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-112287 (URN)
    Conference
    18th International Working Seminar on Production Economics, Innsbruck, Austria, February 24-28, 2014
    Note

    An earlier version of this paper was presented at IWSPE18 2014.

    Available from: 2014-11-21 Created: 2014-11-21 Last updated: 2014-11-21Bibliographically approved
    5. Energy considerations in planning slab furnaces at a steel company: A case study at SSAB
    Open this publication in new window or tab >>Energy considerations in planning slab furnaces at a steel company: A case study at SSAB
    2014 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    To save energy and reduce costs we suggest production planning to consider issues with clear and large impact on both usage and costs of energy. This paper investigates how the energy system interacts with the production processes early in the value chain at a steel company. A case study at one of the company’s production facilities reveals promising opportunities to achieve increased energy efficiency by considering an energy‐related approach in planning of the continuous slab furnaces and the hot rolling processes. Analysis shows that energy can be saved and costs reduced through an alternative planning approach without taking any noteworthy investment cost. Improved communication within the different parts of the organization plays also a significant part in actualizing the managerial opportunities located. Real company data provided from the case company SSAB is used and analyzed. This paper contributes with a model used for analytical calculations on how market conditions could motivate a company to select different planning approaches. This by choosing a primary and secondary slab furnace based on their energy characteristics. As such, when the opportunities are beneficial enough, the impact of energy issues on production and supply chain planning should not be neglected.

    Keywords
    Production planning, energy, steel, process industry, case study
    National Category
    Engineering and Technology Economics and Business Business Administration Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-112288 (URN)
    Conference
    18th International Working Seminar on Production Economics, Innsbruck, Austria, February 24-28, 2014
    Available from: 2014-11-21 Created: 2014-11-21 Last updated: 2014-11-21Bibliographically approved
  • 205.
    Waldemarsson, Martin
    et al.
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Energy issues in supply chain and production planning in the steel industry: A case study at SSAB2014Manuscript (preprint) (Other academic)
    Abstract [en]

    How can a different planning of production and supply chain increase energy efficiency and effectiveness? This descriptive and rather exploratory case study investigates these possibilities by mapping the production system and its supporting energy system at a steel company’s production site. Several possibilities for improvement in the planning processes have been located and evaluated. Our findings resulted in identifying four different improvement areas: 1) planning slab furnaces, 2) utilizing embedded heat and shortening lead times, 3) broader frame when scheduling for decreasing waste at set-ups, and 4) demandresponse opportunities related to electricity price variations. The first improvement area: planning of the slab furnaces, shows the largest potential, both in terms of energy savings and reduced costs. The second and the third improvement areas are similar to each other in terms of potential energy savings, but if the lead-time also could be decreased in the second it would be more economically beneficial than the other. Additional possibilities are found in the fourth improvement area where electricity demand response actions by rescheduling the energy-intensive production into times of low electricity price might save electricity costs. To conclude, the company could reach both higher energy efficiency and profitability simultaneously, by utilizing the energy- and the production systems combined in a more efficient and effective way.

  • 206.
    Waldemarsson, Martin
    et al.
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Energy issues in supply chain and production planning in the steel industry: A case study at SSAB2014In: in Grubbström, R.W, Hinterhuber, H.H., (Eds), PrePrints, Vol. 1, 18th International Working Seminar on Production Economics, Innsbruck, Austria, 2014, p. 489-501Conference paper (Other academic)
    Abstract [en]

    This paper investigates the possibilities of merging suitable processes for energy management into operations management processes within a steel company. The descriptive and rather exploratory case study maps the production system and its supporting energy system within one of the company’s production sites. Several possibilities for improvement in the planning processes have been located and evaluated. Our findings resulted in that four different improvement areas could be identified: planning furnace ovens, utilizing embedded heat and shortening lead times, wider scheduling for decreasing waste at set-ups, and demand-response opportunities related to electricity price variations. Improved planning of the furnace ovens shows the largest potential, both in terms of energy savings and reduced costs. To utilize embedded heat and to reduce waste at set-ups are similar to each other in terms of potential energy savings, but if the lead-time also could be decreased the economical benefits would excel. There are moreover possible economical benefits of electricity demand response actions by rescheduling the energy-intensive production into times of low electricity price. To conclude, the company could reach both higher environmental performance and economical profitability simultaneously, and thus utilizing the energy- and the production systems combined in a more efficient and effective way.

  • 207.
    Waldemarsson, Martin
    et al.
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    How energy affects supply chain planning at a pulp company2013In: 22nd International Conference on Production Research (ICPR 22), 2013Conference paper (Refereed)
    Abstract [en]

    Integrated planning of the supply chain at a multi-site pulp company has previously been considered, in whichenergy are included with respect to its revenue generating capabilities. When energy intense raw materials notonly give fiber to the pulp process but also generate an energy surplus, there is room for different planningapproaches to maximize the total profit. This paper deeply analyses the model with more analytical scenariosand reveals promising changes that can be done in terms of both refining the current planning, but also byimproving the production system and its corresponding energy system. The scenarios considered involvemarket changes for energy demand and price, and alternative production opportunities. The scenarios arecross-analyzed and compared in order to reveal additional relations that are worthy to consider. The findingstherefore point out the usefulness of the model and its advantages.

  • 208.
    Waldemarsson, Martin
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, Faculty of Science & Engineering.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    How energy price changes can affect production- and supply chain planning – A case study at a pulp company2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 203, p. 15p. 333-347Article in journal (Refereed)
    Abstract [en]

    The process industry in general is very energy-intensive, and therefore models focusing on energy can be very important in order to reach higher profitability. In this study, an optimization model of the supply chain in a pulp company, where energy is included with respect to its revenue generating capabilities, is used. Using real company data, and through an analysis of the model’s results, we show that higher profitability can be achieved when integrating energy into the planning process. Our findings show that when energy-intensive raw materials not only provide fibre to the pulp process but also generate an energy surplus, there is room for different planning approaches in order to maximize the total profit. This paper reveals promising changes that can be made for improving the current planning process. The scenarios considered involve market changes for energy demand and price, and also alternative production opportunities. A cross-analysis compares the scenarios in order to reveal additional relations that are important to consider. Depending on a price change of energy, the model prioritizes in its selection of pulp products to produce. From this we provide guidelines on where and when to increase or decrease pulp production. The model shows that the company can increase its total profit no matter which of the included energy parameters that increase in price. The paper contributes to previous research by enhancing the usefulness of this model for not only the case company as such, but also by illustrating and describing how the approach applied can be useful for other cases within the energy intensive industry.

  • 209.
    Waldemarsson, Martin
    et al.
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Rudberg, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Including energy in supply chain planning at a pulp company2012In: Proceedings of the Fourth International Conference on Applied Energy (ICAE) 2012, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper we consider integrated planning of the supply chain at a multi-site pulp company. In addition to the traditional focus on pulp products, also energy aspects are considered, both in the form of raw material and as revenue generating products. The idea is that energy intense raw materials not only gives fiber to the pulp process but also generates an energy surplus that can be used in different ways to create additional value or revenues. The planning horizon is one year and monthly time periods are considered. Decisions included in the planning are purchase and transportation of raw materials from harvest areas to pulp mills, production allocation by dividing the production among the pulp mills, energy mix by choosing the energy input at the pulp mills and distribution of products from mills to customer. An MILP model for the entire supply chain is proposed. A number of different scenarios including real data from the case company are analyzed and evaluated. The aim of the study is thus to investigate the effects on profitability while taking energy issues in consideration.

  • 210.
    Waldemarsson, Martin
    et al.
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Lidestam, Helene
    Linköping University, Department of Management and Engineering, Production Economics. Linköping University, The Institute of Technology.
    Rudberg, Martin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Including energy in supply chain planning at a pulp company2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 1056-1065Article in journal (Refereed)
    Abstract [en]

    In this paper we consider integrated planning of the supply chain at a multi-site pulp company. In addition to the traditional focus on pulp products, also energy aspects are considered, both in the form of raw material and as revenue generating products. The idea is that energy intense raw materials not only gives fibre to the pulp process but also generates an energy surplus that can be used in different ways to create additional value or revenues. The planning horizon is one year and monthly time periods are considered. Decisions included in the planning are; purchase and transportation of raw materials from harvest areas to pulp mills, production allocation by dividing the production among the pulp mills, energy mix by choosing the energy input at the pulp mills, and distribution of products from mills to customer. An MILP model for the entire supply chain is proposed. A number of different scenarios including real data from the case company are analyzed and evaluated. The aim of the study is thus to investigate the effects on profitability while taking energy issues into consideration.

  • 211.
    Wang, Chuan Fei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Xu, Xiaofeng
    Chalmers, Sweden.
    Zhang, Wei
    Lund University, Sweden.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Meng, Xiangyi
    Xi An Jiao Tong University, Peoples R China.
    Bini, Kim
    Chalmers, Sweden.
    Ma, Wei
    Xi An Jiao Tong University, Peoples R China.
    Yartsev, Arkady
    Lund University, Sweden.
    Vandewal, Koen
    Technical University of Dresden, Germany.
    Andersson, Mats R.
    University of South Australia, Australia.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Chalmers, Sweden.
    Low Band Gap Polymer Solar Cells With Minimal Voltage Losses2016In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 6, no 18, article id 1600148Article in journal (Refereed)
    Abstract [en]

    One of the factors limiting the performance of organic solar cells (OSCs) is their large energy losses (E-loss) in the conversion from photons to electrons, typically believed to be around 0.6 eV and often higher than those of inorganic solar cells. In this work, a novel low band gap polymer PIDTT-TID with a optical gap of 1.49 eV is synthesized and used as the donor combined with PC 71 BM in solar cells. These solar cells attain a good power conversion efficiency of 6.7% with a high open-circuit voltage of 1.0 V, leading to the E-loss as low as 0.49 eV. A systematic study indicates that the driving force in this donor and acceptor system is sufficient for charge generation with the low E-loss. This work pushes the minimal E-loss of OSCs down to 0.49 eV, approaching the values of some inorganic and hybrid solar cells. It indicates the potential for further enhancement of the performance of OSCs by improving their V-oc since the E-loss can be minimized.

  • 212.
    Weinberger, Gottfried
    et al.
    University of Gävle, Sweden.
    Amiri, Shahnaz
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering. University of Gavle, Sweden.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering. University of Gavle, Sweden.
    On the benefit of integration of a district heating system with industrial excess heat: An economic and environmental analysis2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 191, p. 454-468Article in journal (Refereed)
    Abstract [en]

    Energy-related cooperation using industrial excess heat (IEH) in district heating (DH) networks shows economic and environmental benefits. A rarely investigated approach is the energy cooperation which incorporates a jointly operated CHP plant also producing process steam for nearby industry. The present study aims to evaluate economic and environmental effects on the Hofors DH system with jointly operated CHP plant when the nearby steel mill extends the supply of recovered IEH. Various IEH supply opportunities with different capacities of hot water and steam were designed and compared with existing IEH utilization, plant heat and electricity production and DH system performance. The energy system model MODEST is used for cost-optimization. A parametric study is used to analyze influences of increasing IEH cost and fluctuating electricity prices. The results show advantages for the DH system to utilize IEH for deliveries of DH and process steam and the cogeneration of electricity. Economic and environmental benefits are decreased total system cost (-1.67 MEUR/a), less use of fuels and electricity, and reduced CO2 emissions with a maximal reachable amount of 28,200 ton/a when the use of biofuel is assumed as limited resource and the substituted marginal electricity production is based on coal condensing power plants. The results also show that industrial steam is a preferred heat supply source as long as the steam cost is below the alternative heat production cost, irrespective of the electricity price. While the cost-effective utilization of industrial hot water for DH is more sensitive and affected by a beneficial CHP production based on higher electricity price segments, it is also shown that utilization of continuously supplied industrial hot water is limited during seasons of low DH demand. (C) 2017 Elsevier Ltd. All rights reserved.

  • 213.
    Weinberger, Gottfried
    et al.
    Univ Gavle, Sweden.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering. Univ Gavle, Sweden.
    Investigating influential techno-economic factors for combined heat and power production using optimization and metamodeling2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 232, p. 555-571Article in journal (Refereed)
    Abstract [en]

    This paper investigates the interaction of a wide range of electricity and fuel prices and technical factors of combined heat and power production in a district heating system. A linear programming-based optimization model with the objective to minimize system cost was used to study the energy systems in the cities of Gavle and Sandviken in Sweden. The comprehensive outcomes from optimization and parametric studies have been analyzed using a polynomial-based metamodel. System costs include variable costs for the production and revenues for sale of heat and electricity. The metamodel is used as an analytical and explanatory tool to interpret input-output relationships. Municipal district heating systems of Gavle and Sandviken in Sweden are studied as an interconnected regional system with improved and new combined heat and power plants. The results show that effects from electricity and fuel prices are important, but that variations in energy system cost may also be caused by many cross-factor interactions with technical factors. A comparative system performance analysis with defined cases and optimal factor setting shows a substantial increase in the electricity production, here by up to 650 GWh annually. The profitability of investing in a new plant depends highly on the considered investment risk and electricity and fuel market prices. CO2 emission savings by up to 466 kton annually can be accomplished if marginal electricity production from coal-condensing power plants is avoided and biofuel is released at the same time.

  • 214.
    Westling, Hanna
    Linköping University, Department of Management and Engineering, Energy Systems.
    Kommuners roll i omställningen till ett hållbart energisystem: med fokus på arbetet gentemot medborgare och näringsliv2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A transition towards a sustainable energy system is of great importance given the climate changes which have been observed and the close link between climate changes and the energy system. Climate change is affecting the planet on a global level and it is therefore of vital importance that actors work together to reduce greenhouse gas emissions and achieve political goals, such as the United Nations' goal which state that the global temperature increase should be kept well below 2 degrees Celsius. 

    Given this background, the aim of the thesis has been to analyse the role of Swedish municipalities in the transition towards a sustainable energy system. The ability for Swedish municipalities to influence the transition has been divided into five areas; their own operations, their own companies, the local business sector, citizens and through cooperation. This thesis has focused on municipalities’ work addressing citizens and the business sector. Cooperation associated with citizens and businesses has also been included in the thesis.

    A literature search and an interview study were used as methods for data collection. The literature search has been conducted to generate a scientific foundation and give a context to the thesis. In the interview study, interviews were held with representatives from eight Swedish municipalities. The selection of municipalities has been strategic and based on The Swedish Association of Local Authorities’ division of municipalities into three main groups; A, B and C. The municipalities that have been interviewed are the City of Stockholm and the City of Malmö from group A, Linköping Municipality, Umeå Municipality and Eskilstuna Municipality from group B and Piteå Municipality, Mora Municipality and Markaryd Municipality from group C. The interview study has resulted in a description of the work related to the transition of the energy system in each municipality.

    It has been concluded that municipalities have an important role in Sweden's transition to a sustainable energy system. Furthermore, it has been indicated that actors at a local and regional level, such as municipalities, have contributed to reduced carbon dioxide emissions in Sweden. In their role, municipalities have the opportunity to influence the energy system through their own operations and their companies as well as other actors such as the local citizens and business sector. They are also able to influence the energy system through cooperation with other actors.

    In the work addressed to citizens and the business sector, the municipalities are able to use tools such as strategic documents, owner directives, physical and economic planning, municipal energy and climate advisors, means and support, and collaboration. They can also use policy instruments and nudging to create incentives in line with municipal targets and visions.

    The analysis shows that the municipalities mainly emphasized municipal energy and climate advisors and business networks as the tools they use in their work addressed to citizens and the business sector. One of the future opportunities and challenges is the municipalities' consideration to the role of citizens and businesses and their inclusion in the energy transition. Municipal self-government and the balance between local adaptation and collaboration are other crucial factors. Opportunities have also been observed by exploring topical areas such as consumption, resources and nudging. The main challenges seen by the municipalities are lack of resources and local adaptation from a national level. It is also important that their prerequisites are maintained consistently over time.

  • 215.
    Wijeratne, Kosala
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Conducting Polymer Electrodes for Thermogalvanic Cells2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fossil fuels are still the dominant (ca. 80%) energy source in our society. A significant fraction is used to generate electricity with a heat engine possessing an efficiency of approximately 35%. Therefore, about 65% of fossil fuel energy is wasted in heat. Other primary heat sources include solar and geothermal energies that can heat up solid and fluids up to 150°C. The growing demand and severe environmental impact of energy systems provide an impetus for effective management and harvesting solutions dealing with waste heat. A promising way to use waste heat is to directly convert thermal energy into electrical energy by thermoelectric generators (TEGs). Solid state TEGs are electronic devices that generate electrical power due to the thermo-diffusion of electronic charge carriers in the semiconductor upon application of the thermal field. However, there is another type of thermoelectric device that has been much less investigated; this is the thermogalvanic cell (TGCs). The TGC is an electrochemical device that consists of the electrolyte solution including a reversible redox couple sandwiched between two electrodes. In our study, we focus on iron-based organometallic molecules in aqueous electrolyte. A temperature difference (Δ𝑇) between the electrodes promotes a difference in the electrode potentials [Δ𝐸(𝑇)]. Since the electrolyte contains a redox couple acting like electronic shuttle between the two electrodes, power can be generated when the two electrodes are submitted to a temperature difference. The focus of this thesis is (i) to investigate the possibility to use conducting polymer electrodes for thermogalvanic cells as an alternative to platinum and carbon-based electrodes, (ii) to investigate the role of viscosity of the electrolyte in order to consider polymer electrolytes, (iii) to understand the mechanisms limiting the electrical power output in TGCs; and (iv) to understand the fundamentals of the electron transfer taking place at the interface between the polymer electrode and the redox molecule in the electrolyte. These findings provide an essential toolbox for further improvement in conducting polymer thermogalvanic cells and various other emerging electrochemical technologies such as fuel cells, redox flow battery, dye-sensitized solar cells and industrial electrochemical synthesis.

    List of papers
    1. Poly(3,4-ethylenedioxythiophene)-Tosylate (PEDOT-Tos) electrode in Thermogalvanic Cells
    Open this publication in new window or tab >>Poly(3,4-ethylenedioxythiophene)-Tosylate (PEDOT-Tos) electrode in Thermogalvanic Cells
    2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 37, p. 19619-19625Article in journal (Refereed) Published
    Abstract [en]

    The interest in thermogalvanic cells (TGCs) has grown because it is a candidate technology for harvesting electricity from natural and waste heat. However, the cost of TGCs has a major component due to the use of the platinum electrode. Here, we investigate new alternative electrode material based on conducting polymers, more especially poly(3,4-ethylenedioxythiophene)-Tosylate (PEDOT-Tos) together with the Ferro/Ferricyanide redox electrolyte. The power generated by the PEDOT-Tos based TGCs increases with the conducting polymer thickness/multilayer and reaches values similar to the flat platinum electrode based TGCs. The physics and chemistry behind this exciting result as well as the identification of the limiting phenomena are investigated by various electrochemical techniques. Furthermore, a preliminary study is provided for the stability of the PEDOT-Tos based TGCs.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2017
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-140745 (URN)10.1039/C7TA04891B (DOI)000411739700007 ()
    Note

    Funding agencies: European Research Council (ERC) [307596]

    Available from: 2017-09-11 Created: 2017-09-11 Last updated: 2018-11-27
    2. Bulk electronic transport impacts on electron transfer at conducting polymer electrode-electrolyte interfaces.
    Open this publication in new window or tab >>Bulk electronic transport impacts on electron transfer at conducting polymer electrode-electrolyte interfaces.
    Show others...
    2018 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, no 7, p. 11899-11904Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    Electrochemistry is an old but still flourishing field of research due to the importance of the efficiency and kinetics of electrochemical reactions in industrial processes and (bio-)electrochemical devices. The heterogeneous electron transfer from an electrode to a reactant in the solution has been well studied for metal, semiconductor, metal oxide, and carbon electrodes. For those electrode materials, there is little correlation between the electronic transport within the electrode material and the electron transfer occurring at the interface between the electrode and the solution. Here, we investigate the heterogeneous electron transfer between a conducting polymer electrode and a redox couple in an electrolyte. As a benchmark system, we use poly(3,4-ethylenedioxythiophene) (PEDOT) and the Ferro/ferricyanide redox couple in an aqueous electrolyte. We discovered a strong correlation between the electronic transport within the PEDOT electrode and the rate of electron transfer to the organometallic molecules in solution. We attribute this to a percolation-based charge transport within the polymer electrode directly involved in the electron transfer. We show the impact of this finding by optimizing an electrochemical thermogalvanic cell that transforms a heat flux into electrical power. The power generated by the cell increased by four orders of magnitude on changing the morphology and conductivity of the polymer electrode. As all conducting polymers are recognized to have percolation transport, we believe that this is a general phenomenon for this family of conductors.

    Place, publisher, year, edition, pages
    National academy of sciences, 2018
    Keywords
    conducting polymer, electron transfer, thermogalvanic cell
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-152759 (URN)10.1073/pnas.1806087115 (DOI)000450642800036 ()30397110 (PubMedID)
    Note

    Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University Faculty Grant [SFO-Mat-LiU 2009-00971]

    Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2019-03-21
  • 216.
    Wirell, Viktoria
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Påverkan av förnybar energi på Singapores energisäkerhet2014Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Singapore is one of the most densely populated countries in the world. At the same time the country has an electricity consumption that is among the highest in the world in relation to the population. They have no indigenous energy resources and are therefore dependent on import of fossil fuels to handle their high electricity consumption. Most of their electricity is generated from natural gas which has been imported in pipelines from Malaysia and Indonesia.

    A consequence of Singapore’s heavy dependence on imported fossil fuels is that they have low energy security. Energy security means that the energy supply should be affordable, reliable and adequate. With its heavy dependence on imported fossil fuels, Singapore is exposed to several energy security risks. These energy security risks could result in detrimental consequences for Singapore.

    The environmental benefits of renewable energy are well known, but how renewable energy can contribute to a better energy security is less known. There are several energy security risks related to the use of fossil fuels and renewable energy can therefore, in the countries that have the right conditions, decrease these risks.

    The purpose of this thesis has been to examine if renewable energy can contribute to a more secure electricity supply in Singapore. To do this, theory regarding Singapore, energy security and different renewable energy sources has been collected. The renewable energy sources that have been examined are wind power, hydropower, geothermal energy, solar power and bioenergy. The theoretical background has then been used to analyze the possibility of using renewable energy sources to improve the energy security in Singapore.   

    The conclusion that can be drawn from this study is that some of the renewable energy sources can contribute to a more secure electricity supply in Singapore. Singapore’s geographical conditions are unfavorable for the use of wind power, hydropower and geothermal energy and these energy sources can therefore not be used to improve the energy security in Singapore. The situation regarding solar power and bioenergy is however different and an increase of the electricity production from these sources can contribute to a more secure electricity supply. 

  • 217.
    Zhang, Yingfeng
    et al.
    Northwestern Polytech Univ, Peoples R China; Northwestern Polytech Univ, Peoples R China.
    Ma, Shuaiyin
    Northwestern Polytech Univ, Peoples R China.
    Yang, Haidong
    Guangdong Univ Technol, Peoples R China.
    Lv, Jingxiang
    Northwestern Polytech Univ, Peoples R China.
    Liu, Yang
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering. Univ Vaasa, Finland.
    A big data driven analytical framework for energy-intensive manufacturing industries2018In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 197, p. 57-72Article in journal (Refereed)
    Abstract [en]

    Energy-intensive industries account for almost 51% of energy consumption in China. A continuous improvement in energy efficiency is important for energy-intensive industries. Cleaner production has proven itself as an effective way to improve energy efficiency and reduce energy consumption. However, there is a lack of manufacturing data due to the difficult implementation of sensors in harsh production environment, such as high temperature, high pressure, high acid, high alkali, and smoky environment which hinders the implementation of the cleaner production strategy. Thanks to the rapid development of the Internet of Things, many data can be sensed and collected in the manufacturing processes. In this paper, a big data driven analytical framework is proposed to reduce the energy consumption and emission for energy-intensive manufacturing industries. Then, two key technologies of the proposed framework, namely energy big data acquisition and energy big data mining, are utilized to implement energy big data analytics. Finally, an application scenario of ball mills in a pulp workshop of a partner company is presented to demonstrate the proposed framework. The results show that the energy consumption and energy costs are reduced by 3% and 4% respectively. These improvements can promote the implementation of cleaner production strategy and contribute to the sustainable development of energy intensive manufacturing industries. (C) 2018 Elsevier Ltd. All rights reserved.

  • 218.
    Zhou, Ke
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Xi An Jiao Tong Univ, Peoples R China.
    Wu, Yang
    Xi An Jiao Tong Univ, Peoples R China.
    Liu, Yanfeng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhou, Xiaobo
    Xi An Jiao Tong Univ, Peoples R China.
    Zhang, Lin
    Xi An Jiao Tong Univ, Peoples R China.
    Ma, Wei
    Xi An Jiao Tong Univ, Peoples R China.
    Molecular Orientation of Polymer Acceptor Dominates Open-Circuit Voltage Losses in All-Polymer Solar Cells2019In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 4, no 5, p. 1057-1064Article in journal (Refereed)
    Abstract [en]

    Low open-circuit voltage (V-oc) induced by energy loss in organic solar cells is considered to be one of the most influencing factors limiting device performance, in which morphology of the active layer plays a crucial role in determining energy loss. By employing a bilayer structure of the P3HT:N2200 all-polymer system, we have identified the isolated impact of a molecular packing structure on device V-oc with analysis of energy loss processes. Thermal annealing and various solvents were used to control molecular orientation in P3HT:N2200 bilayer devices, in which different V-oc spanning from 0.45 to 0.54 V could be obtained. It was found that energy of charge-transfer state (E-ct) differed in these bilayer devices. Besides, increased charge recombination could be observed in bilayer devices when N2200 layers exhibited face-on orientation, which caused an additional energy loss and decreased V-oc. Our results suggest that rational control of polymer molecular orientation is essential to reduce the energy loss and ultimately achieve high V-oc in all-polymer solar cells.

  • 219.
    Åberg, Magnus
    et al.
    Uppsala University, Sweden.
    Molin, Andreas
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Wäckelgård, Ewa
    Uppsala University, Sweden.
    Moshfegh, Bahram
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
    Greenhouse Gas Emission from General District Heat use in Sweden: An Approach for Justified Comparisons in Residential Energy Use2009In: Scientific Conference on Energy Saving and Green Energy, Älvsjömässan, Stockholm, 2009Conference paper (Refereed)
    Abstract [en]

    Significant uncertainties regarding the evaluation of environmental impact from the use ofenergy motivates the need for a unified evaluation approach. In this paper a marginalapproach for general evaluation of CO2 equivalent emissions from the use of district heat inSweden is proposed. A predefined national marginal heat production mix is used to define amarginal heat evaluation approach to calculate the greenhouse gas emissions from the use ofdistrict heating. The novel approach offers a method for justified comparisons of differenttypes of energy use. By using the marginal heat evaluation approach it was shown that theevaluation of the electricity used in heat production for district heating is significant for theCO2 equivalent emissions. A survey of general district heating CO2 emission evaluationexamples is also included in the paper. The marginal heat use approach generates high CO2equivalent emission values in comparison with earlier studies. The overall conclusion of thepaper is that there is a need for further research and discussion regarding development ofmethods for energy use evaluation. The general marginal heat use approach is part of thesolution to this problem.

2345 201 - 219 of 219
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