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  • Study location Room Delta, Mälardalen university campus Västerås and via Zoom
  • 2021-06-18 09:00–12:00

The public defense of Mahsa Daraeis’ doctoral thesis in Energy and Environmental Engineering

The public defense of Mahsa Daraeis’ doctoral thesis in Energy and Environmental Engineering will take place at Mälardalen University, room Delta and via Zoom at 09.00 on June 18, 2021.

Title: ”Production planning of CHP plants in transition towards energy systems with high share of renewables ”

The faculty examiner is Professor Louise Ödlund, Linköping University and the examining committee consists of Professor Viktoria Martin, KTH, Associate Professor Peter Sorknaes, Aalborg University and Professor Sanna Syri, Aalto University.

Reserve: Professor Clas Eriksson, Mälardalen University.

The doctoral thesis has serial number 335.

If you wish to participate, pleas contact Madeléne Westerberg at madelene.westerberg@mdh.se


The share of Renewable Energy Sources (RES) in the global energy supply, especially in the power sector, is growing. Energy supply from RES, such as wind and solar power, depends on weather conditions and it can intermittently change even over a short-time period. Therefore, the increased share of renewables in energy supply indicates the crucial necessity for flexibility in the system to respond to the imbalances between demand and supply. From the production planning perspective, expansion of the renewable energy supply as well as integration of new energy conversion and storage technologies could add to the complexity of the current energy system. Moreover, several parameters, including trends in energy demand and supply, availability of resources, market prices, and climate conditions influence the optimal performance of the future energy system. Thus, optimization of such a complex energy system is important.

The goal of this thesis is to assess the potential of existing combined heat and power (CHP) plants to be integrated with power supply from rooftop photovoltaic (PV) systems. Moreover, given the above-mentioned challenges, the impacts of high interrelation with renewables on the system flexibility and the possible directions in production planning of the CHP plants are investigated. Two cases have been developed and modelled for the system optimization and flexibility analyses. The first case investigates the impacts of long-term energy storage using power-to-hydrogen technology on the system flexibility. The second case assesses the potential of polygeneration by integrating bioethanol production and pyrolysis process with existing CHP plants. The optimization is performed using Mixed Integer Linear Programming (MILP) method. For better understanding of some of the future challenges related to changes in energy demand and supply, market trends, and climate change, different scenarios have been developed and investigated. The results of the studied cases are compared and evaluated to find the optimal integration pathway to maximize the renewables share and minimize the operation costs.

According to the investigation results, potential power supply from the proposed rooftop PV systems can contribute to decreasing the total power imports to the studied system. As the findings suggest the inclusion of power storage using power-to-hydrogen technology could improve the system flexibility. The studied polygeneration systems in this thesis indicate that the integration of biofuel production with existing CHP plants can increase the total heat and power outputs and subsequently increase the operation of CHP plants in the system.

The main conclusion of the thesis is that the interconnections between heating, power, and transportation sectors enable the integration of renewables to the energy system and increase the system flexibility. Market trends related to the electrification of the transportation system, increased use of heat pumps as direct heating sources, and variations in the electricity price can significantly influence the operational strategy of the existing CHP plants. Moreover, these trends increase the RES penetration in the system while enhancing the power imports and the system costs.

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