| 1. |
- Avelin, Anders, et al.
(författare)
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Use of combined physical and statistical models for online applications in the pulp and paper industry
- 2009
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Ingår i: Mathematical and Computer Modelling of Dynamical Systems. - : Informa UK Limited. - 1387-3954 .- 1744-5051. ; 15:5, s. 425-434
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses the accuracy of different types of models. Statistical models are based on process data and/or observations from lab measurements. This class of models are called black box models. Physical models use physical relationships to describe a process. These are called white box models or first principle models. The third group is sometimes called grey box models, being a combination of black box and white box models. Here we discuss two examples of model types. One is a statistical model where an artificial neural network is used to predict NOx in the exhaust gases from a boiler at Mlarenergi AB in Vsters, Sweden. The second example is a grey box model of a continuous digester. The digester model includes mass balances, energy balances, chemical reactions and physical geometrical constraints to simulate the real digester. We also propose that a more sophisticated model is not required to increase the accuracy of the predicted measurements.
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| 2. |
- Blarke, Morten B, et al.
(författare)
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Intermittency-friendly and high-efficiency cogeneration : Operational optimisation of cogeneration with compression heat pump, flue gas heat recovery, and intermediate cold storage
- 2011
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 36:12, s. 6867-6878
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Tidskriftsartikel (refereegranskat)abstract
- This paper develops, implements, and applies a mathematical model for economic unit dispatch for a novel cogeneration concept (CHP-HP-FG-CS (CHP with compression heat pump and cold storage using flue gas heat)) that increases the plant's operational flexibility. The CHP-HP-FG-CS concept is a high-efficiency and widely applicable option in distributed cogeneration better supporting the co-existence between cogenerators and intermittent renewables in the energy system. The concept involves integrating an efficient high-temperature compression heat pump that uses only waste heat recovered from flue gases as low-temperature heat source, and an intermediate cold thermal storage allowing for non-concurrent operation of the cogeneration unit and the heat pump unit. The model is applied for a paradigmatic case study that shows how the integration of a heat pump affects the operational strategy of a cogeneration plant. It is found that CHP-HP-FG-CS offers significant reductions in fuel consumption (-8.9%) and operational production costs (-11.4%). The plant's fuel-to-energy efficiency increases from 88.9 to 95.5%, which is state-of-the-art. The plant's intermittency-friendliness coefficient Rc improves only marginally due to the constrained nature of the low-temperature heat source and the associated small capacity of the heat pump unit. Significant improvements in Rc are found when increasing the heat pump capacity assuming the availability of an unconstrained heat source
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| 3. |
- Daianova, Lilia, et al.
(författare)
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Evaluation of a regional bioenergy system with local production of biofuel for transportation, integrated with a CHP plant
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 92, s. 739-749
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Tidskriftsartikel (refereegranskat)abstract
- The share of renewable liquid fuels (ethanol, fatty acid methyl ester, biogas, and renewable electricity) in the total transportation fuel in Sweden, has increased by the end of 2009 to such level that e.g. domestic bioethanol production is unable to satisfy current ethanol fuel demand. Regional small-scale ethanol production can assist the region in covering the regional needs in transport fuel supply. Current case study system includes the production of ethanol, biogas, heat and power from locally available cereals straw. A mixed integer programming (MIP) model is developed for cost optimization of regional transport fuel supply (ethanol, biogas and petrol). The model is applied for two cases, one when ethanol production plant is integrated with an existing CHP plant (polygeneration), and one with a standalone ethanol production plant. The optimization results show that for both cases the changes in ethanol production costs have the biggest influence on the costs for supplying regional passenger car fleet with transport fuel. Petrol fuel price and straw production costs have also a significant effect on costs for supplying cars with transport fuel for both standalone ethanol production and integrated production system. By integrating the ethanol production process with a CHP plant, the costs for supplying regional passenger car fleet with transport fuel can be cut by 31%, from 150 to 104 (sic)/MW h fuel, which should be compared with E5 costs of 115 E/MW h (excl VAT).
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| 4. |
- Daianova, Lilia, et al.
(författare)
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Local production of bioethanol to meet the growing demands of a regional transport system
- 2011
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Ingår i: Proceedings of World Renewable Energy Congress 2011, May 2011, Linköping, Sweden.
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Konferensbidrag (refereegranskat)abstract
- : Energy security and the mitigation of greenhouse gas emissions (GHG) are the driving forces behind the development of renewable fuel sources worldwide. In Sweden, a relatively rapid development in bioethanol usage in transportation has been driven by the implementation of national taxation regulations on carbon neutral transport fuels. The demand for bioethanol to fuel transportation is growing and cannot be met through current domestic production alone. Lignocellulosic ethanol derived from agricultural crop residues may be a feasible alternative source of ethanol to secure a consistent regional fuel supply in Swedish climatic conditions. This paper analyzes how the regional energy system can contribute to reducing CO2 emissions by realizing local small scale bioethanol production and substituting petrol fuel with high blend ethanol mixtures for private road transport. The results show that about 13 000 m3 of bioethanol can be produced from the straw available in the studied region and that this amount can meet the current regional ethanol fuel demand. Replacing the current demand for petrol fuel for passenger cars with ethanol fuel can potentially reduce CO2 emissions from transportation by 48%.
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| 5. |
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| 6. |
- Daraei, Mahsa, 1991-, et al.
(författare)
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Evaluation of biofuel production integrated with existing CHP plants and the impacts on production planning of the system – A case study
- 2019
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 252
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Tidskriftsartikel (refereegranskat)abstract
- The increasing atmospheric CO2 concentration has caused a transformative shift in global energy systems, which is contributing to an increased use of renewables. Sweden is among the countries trying to shift to a fossil-fuel-free system in all energy sectors. This paper addresses the fuel demand and supply in the transportation sector in the county of Västmanland in Sweden. A Mixed Integer Linear Programming optimization model is developed to minimize cost in the studied system. The model is further used to investigate the influence of three different scenarios on production planning of regional Combined Heat and Power (CHP) plants: (1) straw-based biofuel production integrated with existing CHP plants to fuel combustion engine vehicles, (2) use of electric vehicles, and (3) use of hybrid vehicles fueled by both electricity and bioethanol. Potential solar power generation from rooftop solar cells is also included in the model. The energy system in scenario 2 is found to have the highest overall system efficiency; however, a large amount of power needs to be imported to the system. Hybrid vehicles can potentially reduce the electricity import and CO2 emissions compared to the current situation. Electricity production from rooftop solar collectors could provide the energy needs of the vehicles during summer, while regionally produced straw-based bioethanol integrated with CHP plants can satisfy the fuel needs of the vehicles in winter. This approach could affect the production planning of CHP plants, result in less fuel use and increase the share of renewable resources in the regional transportation system.
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| 7. |
- Daraei, Mahsa, 1991-, et al.
(författare)
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Evaluation of potential fossil fuel free energy system: Scenarios for optimization of a regional integrated system
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 142, s. 964-970
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Tidskriftsartikel (refereegranskat)abstract
- Population growth and urbanization have led to increases in energy demand and consequently, greenhouse gas emissions. Therefore, the availability of the fossil fuel as the main source of energy supply has been changed. Utilization of renewable resources including solar, wind, and hydropower together with distributed energy systems could eliminate the dependency on fossil fuel energy sources. In this paper, energy use and supply trends have been studied for the Counties of Västmanland and Södermanland in Sweden in order to develop a scenario for the regional energy system in 2030. The aim is to use the scenario for evaluation of the impacts of regional renewable energy resources on the production planning of CHP plants. The scenario shows that there is not enough potential for electricity production from renewable resources such as solar, wind, and hydropower to fulfill the estimated demand in 2030. Around 75% of electricity needs in Västmanland and 89% of power demands in Södermanland need to be met by imported electricity to these regions. Efficiency improvements and a more complex energy system integrating also with other energy resources like biomass, waste and industrial waste heat are necessary to develop a sustainable energy system.
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| 8. |
- Daraei, Mahsa, 1991-, et al.
(författare)
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Potential biofuel production in a fossil fuel free transportation system : A scenario for the County of Västmanland in Sweden
- 2019
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Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; , s. 1330-1336
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Konferensbidrag (refereegranskat)abstract
- Air pollution and increased CO2 concentration in atmosphere and other energy related issues caused a transformative shift in energy system which contributes to increased utilization of renewables as alternative to generate green energy carriers. The potential of renewable resources in different region and potential energy conversion have been largely considered by many researcher in many countries. The energy conversion technologies to produce heat, electricity, and transportation fuels have made impressive technical advances. Sweden has also been challenging with mitigation of CO2 emission and trying to shift into a fossil fuel free system in all energy sectors. This paper deals with the current status of fuel demand and supply in the transport sector in a County in Sweden. A scenario for a fossil fuel free transport sector at a regional level is developed to investigate the potential biofuel production from regionally produced straw. The results and analysis indicate that the potential for cereal based bioethanol production in the region is sufficient to meet the biofuel demand of the County. Using the fallow land for cereal cultivation, it is feasible to shift into a fossil fuel free transportation system where all passenger cars are fueled by bioethanol. The results and finding from the current paper will be used to develop further study on optimization of local biofuel production integrated with CHP plants considering application of other feedstock such as municipal wastes.
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| 9. |
- Daraei, Mahsa, 1991-, et al.
(författare)
-
Potentials for increased application of renewables in the transportation system : A case study for Södermanland County, Sweden
- 2019
-
Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; , s. 267-273
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Konferensbidrag (refereegranskat)abstract
- In this study, possible alternations in a regional transport sector are assessed to increase the use of renewable resources. Three scenarios are developed aimed to investigate different alternatives including potential straw-based bioethanol supply to fuel regional cars with combustion engines, more use of Electrical Vehicles (EVs) with use of potential power from solar energy, and the feasibility of application of hybrid cars fueled with electricity and bioethanol. The evaluation considers the reduction in CO 2 emissions and increased balance in energy demand and supply. Results of the study indicate that application of hybrid vehicles with bioethanol-fueled engines and electrical motors could potentially reduce the CO 2 emissions compared with other proposed approaches in the studied scenarios. At the same time, there would be a balance in the system, so that, the bioethanol production from the available cereal straw in the region can meet the energy demand of suggested hybrid cars in wintertime. While, the energy supply from solar cells installed on the rooftop of the buildings can cover the electricity need of the motor during summer. This approach will also result in increased use of renewables in the transportation system.
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| 10. |
- Daraei, Mahsa, 1991-
(författare)
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Production planning of CHP plants integrated with bioethanol production and local renewables
- 2019
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Production planning of an energy system is dependent on parameters such as energy demand and energy conversion technologies, which are influential in making decisions on operation strategy and optimal performance of the system. In accordance with the European Union energy policy, the share of renewable resources in the energy supply is growing. Improvement in energy technology is considered to be a pathway to achieve the target of 100% renewable power supply in Sweden by 2040. Increased utilization of renewable resources in energy systems and transportation sectors as well as improved energy conversion technologies would add complexity to the systems. Development of such complex systems depends on several key parameters, including availability of local resources, changes in daily energy use behavior, market price and weather conditions. Therefore, optimization and long-term production planning of such systems will be crucial considering the alternating nature of renewable resources. The aim of this thesis is to develop an optimization model for a regional energy system to provide advanced knowledge for production planning for combined heat and power (CHP) plants. The energy system in the county of Västmanland in central Sweden is used as the case for study. The regional system consists of CHP plants, heat only boilers and renewable resources. Two different optimization cases are developed for the analysis, one with increased energy supply from local renewables, and the other with integrated transport fuels production in a polygeneration system. The model includes the whole chain from availability of resources to the final energy use. The effect of different parameters relating to trends in energy demand and supply on operational strategy of the studied system is investigated by developing different scenarios. The potential solar power production from grid-connected solar cells installed on the rooftops of buildings in the region is added to the system in the base scenario. Then, the first scenario analyzes the increased application of heat pumps to replace the district heating in some of the buildings in the region. The influence of electrification of the transportation system as a result of increased penetration of electric vehicles is investigated in the second scenario. Two further scenarios evaluate the effects of integration of bioethanol production with existing CHP plants and increased application of bioethanol cars and hybrid vehicles in the regional transportation system. The study demonstrates the importance of production planning of the energy system at the regional scale in relation to resource availability and energy imports. The main conclusion of this thesis is that the polygeneration and increased use of heat pumps could influence the production planning of the system in terms of fuel use, plants operation, fossil-based emissions, and energy demand and import. However, increased use of hybrid vehicles represents the optimal case for the mentioned parameters.
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