Public thesis defence of Samira Fazlollahi
© 2014 EPFL
On the 14th of March the public thesis defense of Samira Fazlollahi will take place (17h15 in CM4). Her PhD thesis entitled "Decomposition optimization strategy for the design and operation of district energy systems" was supervised by Prof. François Maréchal and is accessible through infoscience and the EPFL library (N°6130).
Abstract
In the present context of sustainable development, a variety of energetic, economic and environmental benefits can be achieved by district energy systems, which can be pointed out as; energy efficiency, decrease the CO2 intensity and environmental impacts, reliability, waste heat recovery, fuel flexibility and cost saving. The design and operation of energy systems are key issues in order to obtain these benefits.
The aim of the present work described in this thesis is to develop a method and a computa- tional framework, that helps decision makers define the optimal design and the operating strategy of a district energy system with regard to the sustainability and the profitability.
The developed model combines conversion technologies modeling, energy integration techniques, Geographical Information System (GIS), global sensitivity analysis, economic evaluation and environmental impact assessment in a multi-objective, multi-period mixed integer non linear optimization framework. It has the aim of obtaining a set of optimal solutions in the form of a Pareto frontier. To solve the non linear optimization model, a decomposition strategy including a master and a slave problem was developed.
The proposed method helps the decision maker to know; Which type and size of poly- generation technologies (centralized and decentralized) and with which type of resources are best suited for the district? Where in the district shall these technologies be implemented (geographical locations)? Is it viable to combine these technologies with other advance technologies like heat pumps and solar PV? Which operating strategy is to be followed? What are the optimal layout, supply and return temperatures of distribution pipelines?
The developed methodology is illustrated by several test cases. The last case study deals with the design and the synthesis of energy systems in an urban area with 450,000 inhabitants. The overall system from resources and supply side to services and consumers side are synthesized. Results show that by integrating the district heating networks the overall system efficiency can be improved from 34% to 75%, with simultaneous costs and emissions reduction of 22-27% and 50-65% respectively.
Keywords: District energy systems, Mixed Integer Non Linear Programming, Evolutionary algorithm, Thermo-economic modeling, CO2 mitigation, daily thermal storage, typical operating periods.
