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  • 1.
    Afzali Gorouh, Hossein
    et al.
    Shahid Bahonar University of Kerman, Iran.
    Salmanzadeh, Mazyar
    Shahid Bahonar University of Kerman, Iran.
    Nasseriyan, Pouriya
    Shahid Bahonar University of Kerman, Iran.
    Hayati, Abolfazl
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Cabral, Diogo
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Gomes, João
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Karlsson, Björn
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Thermal modelling and experimental evaluation of a novel concentrating photovoltaic thermal collector (CPVT) with parabolic concentrator2022Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 181, s. 535-553Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, a zero-dimensional thermal model has been developed to analyze a novel low concentration photovoltaic-thermal (CPVT) collector. The model has been developed by driving heat transfer and energy balance equations for each part of the collector and then solving all the equations simultaneously. Moreover, a Monte-Carlo ray-tracing software has been used for optical stimulations of the parabolic trough solar collector. The novel CPVT collector has been experimentally tested at Gävle University (Sweden) and the model has been validated against the experimental results. The primary energy saving equivalent to the thermal-electrical power cogeneration of the CPVT collector has been determined. The effect of glass cover removal, heat transfer fluid (HTF) inlet temperature and mass flow rate on the collector performance has been investigated. The optimum HTF mass flow rates of the collector for maximum electrical yield and overall primary energy saving were determined under specified operating conditions by considering the pump consumption. The effect of mean fluid temperature on the thermal and electrical efficiencies has been studied and the characteristic equation of the thermal efficiency has been obtained. The thermal and electrical peak efficiencies of the collector have been found to be 69.6% and 6.1%, respectively.

    Fulltekst (pdf)
    fulltext
  • 2.
    Amiri, Shahnaz
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energiteknik. Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Henning, Dag
    Optensys Energianalys, Linköping, Sweden .
    Karlsson, Björn G.
    Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden .
    Simulation and introduction of a CHP plant in a Swedish biogas system2013Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 49, s. 242-249Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objectives of this study are to present a model for biogas production systems to help achieve a more cost-effective system, and to analyse the conditions for connecting combined heat and power (CHP) plants to the biogas system. The European electricity market is assumed to be fully deregulated. The relation between connection of CHP. increased electricity and heat production, electricity prices, and electricity certificate trading is investigated. A cost-minimising linear programming model (MODEST) is used. MODEST has been applied to many energy systems, but this is the first time the model has been used for biogas production. The new model, which is the main result of this work, can be used for operational optimisation and evaluating economic consequences of future changes in the biogas system. The results from the case study and sensitivity analysis show that the model is reliable and can be used for strategic planning. The results show that implementation of a biogas-based CHP plant result in an electricity power production of approximately 39 GW h annually. Reduced system costs provide a profitability of 46 MSEK/year if electricity and heat prices increase by 100% and electricity certificate prices increase by 50%. CO2 emission reductions up to 32,000 ton/year can be achieved if generated electricity displaces coal-fired condensing power.

  • 3.
    Amiri, Shahnaz
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem. Department of Management and Engineering, Division of Energy Systems, Linköping University, Linköping, Sweden.
    Weinberger, Gottfried
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Energisystem.
    Increased cogeneration of renewable electricity through energy cooperation in a Swedish district heating system - A case study2018Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 116, s. 866-877Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study of the district heating (DH) system in the city of Kisa, Sweden, shows how, through energy cooperation with a nearby sawmill and paper mill, a local energy company contributes to energy-efficient DH and cost-effective utilization of a new biofuel combined heat and power (CHP) plant. Cases of stand-alone and integrated energy systems are optimized with the linear program MODEST. The European power market is assumed to be fully deregulated. The results show clear advantages for the energy company to cooperate with these industries to produce heat for DH and process steam for industry. The cooperating industries gain advantages from heat and/or biofuel by-product supply as well. The opening to use a biofuel CHP plant for combined heat supply results in cogenerated electricity of almost 29 GWh/a with an increased biofuel use of 13 GWh/a, zero fuel oil use and CO2 emission reductions of 25,800 tons CO2/a with coal-condensing power plant on the margin and biofuel as limited resource. The total system cost decreases by −2.18 MEUR/a through extended cooperation and renewable electricity sales. The sensitivity analysis shows that the profitability of investing in a biofuel CHP plant increases with higher electricity and electricity certificate prices.

  • 4.
    Eriksson, Ola
    et al.
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för bygg- energi- och miljöteknik, Miljöteknik. Profu AB, Mölndal, Sweden.
    Bisaillon, Mattias
    Haraldsson, Mårten
    Sundberg, Johan
    Integrated waste management as a mean to promote renewable energy2014Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 61, s. 38-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Management of municipal solid waste is an efficient method to both increase resource efficiency (material and energy recovery instead of landfill disposal) and to replace fossil fuels with renewable energy sources (waste is renewable in itself to a large extent as it contains paper, wood, food waste etc.). The paper presents the general outline and results from a comprehensive system study of future waste management. In the study a multifunctional waste management system integrated with local energy systems for district heating and electricity, wastewater treatment, agriculture and vehicle fuel production is investigated with respect to environmental impact and financial economy. Different waste technologies as well as management strategies have been tested. The treatment is facilitated through advanced sorting, efficient treatment facilities and upgrading of output products. Tools used are the ORWARE model for the waste management system and the MARTES model for the district heating system. The results for potential global warming are used as an indicator for renewable energy. In all future scenarios and for all management strategies net savings of CO2 is accomplished. Compared to a future reference the financial costs will be higher or lower depending on management strategy. 

  • 5.
    Granqvist, C. G.
    et al.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Azens, A.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Kullman, L.
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Rönnow, Daniel
    Department of Technology, Uppsala University, Uppsala, Sweden.
    Progress in Smart Windows Research: Improved Electrochromic W Oxide Films and Transparent Ti-Ce Oxide Counter Electrodes1996Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 8, nr 1-4, s. 97-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review recent work on sputter deposited W-oxide-based films. Improved electrochemical durability was obtained by electron bombardment during deposition, and enhanced coloration/bleaching dynamics was obtained by fluorination. Spectrally resolved scattering measurements indicated that haze levels ≪ 1 % could be reached. Oblique angle deposition could yield angular selectivity. New results are given for sputtered Ti-Ce oxide films, showing their capacity as counter electrodes in transparent electrochromic devices.

  • 6.
    Lindahl, Johan
    et al.
    Chalmers University of Technology.
    Lingfors, David
    Uppsala University.
    Elmqvist, Åsa Katarina
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för datavetenskap och samhällsbyggnad, Besluts-, risk- och policyanalys.
    Mignon, Ingrid
    Economic analysis of the early market of centralized photovoltaic parks in Sweden2022Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 185, s. 1192-1208Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sweden are one of the countries that experience growing installation volumes of Solar photovoltaic. Traditionally, in Sweden, most of the solar photovoltaic investments and policy incentives have focused on distributed photovoltaic systems. Yet, despite limited policy incentives and pessimistic forecasts, an increasing number of centralized photovoltaic parks have been commissioned and plans for substantial new capacities are communicated. Hence, the current paper investigates why. Detailed information about the underlying costs of six PV parks commissioned in2019 and 2020 in Sweden were obtained by in-depth interviews with stakeholders and were analysed through levelized cost of electricity calculations. We conclude that the unsubsidised levelized cost of electricity ranged from 27.37 to 49.39 €/MWh, with an average of 40.79 €/MWh. This is lower than what are assessed for photovoltaic parks in some recent Swedish electricity system scenario studies. The main reason for the discrepancy is identified to be the assumed interest rates in the system scenario studies and the actual cost of capital experienced in the market. Comparing the levelized cost of electricity values with the market value of solar photovoltaic electricity on the spot market show that four of the six studied parks would be profitable under a merchant business model with the last years spot prices. If the downward price trend continues, Sweden may face an unexpected expansion of photovoltaic parks.

    Fulltekst (pdf)
    fulltext
  • 7.
    Mulenga, Enock
    et al.
    Department of Engineering Science and Mathematics, Luleå University of Technology.
    Kabanshi, Alan
    Högskolan i Gävle, Akademin för teknik och miljö, Avdelningen för byggnadsteknik, energisystem och miljövetenskap, Energisystem och byggnadsteknik.
    Mupeta, Henry
    Department of Electrical Engineering, The Copperbelt University, Jambo Drive, Riverside, P.O. Box 21692, Kitwe, Zambia.
    Ndiaye, Musa
    Department of Electrical Engineering, The Copperbelt University, Jambo Drive, Riverside, P.O. Box 21692, Kitwe, Zambia.
    Nyirenda, Elvis
    ZESCO Limited, PO Box 33304, Lusaka, Zambia.
    Mulenga, Kabwe
    ZESCO Limited, PO Box 33304, Lusaka, Zambia.
    Techno-economic analysis of off-grid PV-Diesel power generation system for rural electrification: A case study of Chilubi district in Zambia2023Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 203, s. 601-611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study explores the techno-economic feasibility and viability of a Photovoltaic-Diesel Hybrid system for rural electrification in sub-Sahara Africa with a case study of Chilubi island, a remote district without access to electricity in the Northern Province of Zambia. Using HOMER (Hybrid Optimization of Multiple Electric Renewables) Pro software, the best and most feasible technical solutions through different hybrid system configurations, combinations and the district's rate of access to electricity were considered based on the least Levelized Cost of Energy (LCoE) and life cycle costs of the project. The results show that operating diesel generators as stand-alone is not economically sustainable and has a high LCoE. Influencing factors include variability in diesel pump prices, high fuel transportation costs, high cost of operation and maintenance, among other factors of concern. 100% photovoltaic (PV) with a battery system gave the lowest LCoE. However, the initial capital cost of solar energy projects in Zambia is relatively high compared to the equivalent diesel-based plants, as shown herein. It explains why diesel power plants are favoured for off-grid settlements. On the hand, the low operational cost and LCoE of PV power plants favour rural districts as they offset the high initial capital costs. Additionally, the continued downward trend in the cost of PV installations per kWp has opened discussions among policymakers and energy planners in Zambia to favour rural electrification with renewable energy-based power generation. This study contributes to this discussion.

    Fulltekst (pdf)
    fulltext
  • 8.
    Natarajan, Karthikeyan
    et al.
    University of Eastern Finland .
    Leduc, Sylvain
    International Institute for Applied Systems Analysis (IIASA), A-2361 Laxenburg, Austria .
    Pelkonen, Paavo
    University of Eastern Finland.
    Tomppo, Erkki
    Finnish Forest Research Institute (METLA), Vantaa, Finland.
    Dotzauer, Erik
    Mälardalens högskola, Framtidens energi.
    Optimal locations for second generation Fischer Tropsch biodiesel production in Finland2014Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 62, s. 319-330Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A country level spatially explicit mixed integer linear programming model has been applied to identify the optimal Fischer Tropsch biodiesel production plants locations in Finland. The optimal plant locations with least cost options are identified by minimizing the complete costs of the supply chain with respect to feedstock supply (energywood, pulpwood, sawmill residuals, wood imports), industrial competition (pulp mill, sawmill, combined heat and power plants, pellet industries) and energy demand (biodiesel, heat, biofuel import). Model results show that five biodiesel production plants of 390MW feedstock are needed to be built to meet the 2020 renewable energy target in transport (25.2PJ). Given current market conditions, the Fischer Tropsch biodiesel can be produced at a cost around 18€/GJ including by-products income. Furthermore, the parameter sensitivity analysis shows that the production plant parameters such as investment costs and conversion efficiency are found to have profound influence on the biodiesel cost, and then followed by feedstock cost and plant size. In addition, the variations in feedstock costs and industrial competition determine the proportion of feedstock resource allocation to the production plants. The results of this study could help decision makers to strategically locate the FT-biodiesel production plants in Finland.

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