Economical, environmental and exergetic multi-objective optimization of district heating systems on hourly level for a whole year

Scientific paper - Original scientific paper

• Author: Hrvoje Dorotić
• Author: Tomislav Pukšec
• Author: Neven Duić
• Author's institution: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; (Department of Energy, Power and Environmental Engineering); (Power Engineering and Energy Management Chair)
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Process Energy Engineering

Abstract (english)

District heating systems are proven to be an effective way of increasing energy efficiency, reducing the environmental impact and achieving higher exergy efficiency than individual heating solutions. The leaders in
district heating integration are Scandinavian countries with more than 50% of the covered total heating demand.
Nevertheless, these systems haven’t reached their full potential in most European countries. The reason for this
could be that energy planners often study only the economic feasibility of the system, thus neglecting other
crucial aspects of the previously mentioned district heating. In research papers, district heating multi-objective
optimization usually takes into account the minimization of the total discounted cost and the environmental
impact. Most times, these two objectives are studied as a single objective optimization problem through the
internalization of the cost related to carbon dioxide emissions. This paper presents the multi-objective optimization method which is capable of optimizing district heating technology supply capacities and their operation,
including thermal storage, for a one-year time horizon in order to satisfy the optimization goals. The model was
written in the open-source and free programming language called Julia, while linear programming solver named
Clp was used to obtain the solution. The solver is part of Julia’s optimization package called JuMP. Three
separate objective functions are included in the model: the minimization of the total discounted cost, the
minimization of carbon dioxide emissions and the minimization of exergy destruction. Since these three goals
are often in conflict, the final result of multi-objective optimization is the so-called Pareto surface which presents
the compromise between all possible results. To deal with the multi-objective optimization problem, the
weighted sum method in combination with the epsilon-constraint method was used. The most suitable result has
been chosen using the knee point method which is a solution the closest to the Utopia solution where all three
goals reach their optimal value.

• Keywords (english): District heating; Exergy; Multi-objective optimization; Linear programming; Thermal storage
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Applied Energy
• Numbering: vol. 251, 113394
• p-ISSN: 0306-2619
• e-ISSN: 1872-9118
• DOI: https://doi.org/10.1016/j.apenergy.2019.113394
• URN:NBN: urn:nbn:hr:235:077063
• Publication: 2019
• Type of resource: Text
• Access conditions: Open access
• Created on: 2024-06-03 15:05:41