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Multi-criteria analysis of the integration of Solar Thermal Collectors and Borehole Thermal Energy Storage Systems into existing District Heating Grids

Formhals, J. and Welsch, B. and Sass, I. (2019):
Multi-criteria analysis of the integration of Solar Thermal Collectors and Borehole Thermal Energy Storage Systems into existing District Heating Grids.
In: 10th European Geothermal PhD Day 2019, Potsdam, Germany, 25.-27.02.2019, [Conference or Workshop Item]

Abstract

Solar district heating (SDH) is a rapidly expanding technology, which can help to replace large amounts of conventionally produced thermal energy by renewable heat. However, the inherent seasonal mismatch of heat demand and solar heat supply reduces its potential substantially. This drawback can be overcome by seasonal thermal energy storage. Due to their large capacities, Borehole Thermal Energy Storage (BTES) systems are particularly suited for district scale solutions. The efficiency of those systems and their components is highly dependent on the implemented operational temperature levels. To quantify those interdependent and partially opposing effects, a numerical case study is carried out, in which a SDH system with BTES is integrated into an existing district heating grid. For this purpose, a coupled numerical simulation approach has been developed, in which the above- and below-ground parts of the system are considered each in dedicated software environments. The BTES is simulated using FEFLOW, a finite-element software tool, taking into account the specific geology of the site under investigation. The SDH is simulated in SimulationX, a system simulation suite based on Modelica, providing detailed information about energy supply, demand and losses of the grid and each component. 16 different scenarios for the grid and storage discharge temperatures are analyzed taking into account energetic, economic and ecological criteria. The results show that optimal solutions can vary considerably according to the weighting of objectives. Furthermore, the study reveals that the optimization of the overall system in a multi-objective approach is much more important than focusing on component efficiencies only. However, the results are highly sensitive to economic boundary conditions. Accordingly, the considered regulatory framework and energy prices are very important.

Item Type: Conference or Workshop Item
Erschienen: 2019
Creators: Formhals, J. and Welsch, B. and Sass, I.
Title: Multi-criteria analysis of the integration of Solar Thermal Collectors and Borehole Thermal Energy Storage Systems into existing District Heating Grids
Language: English
Abstract:

Solar district heating (SDH) is a rapidly expanding technology, which can help to replace large amounts of conventionally produced thermal energy by renewable heat. However, the inherent seasonal mismatch of heat demand and solar heat supply reduces its potential substantially. This drawback can be overcome by seasonal thermal energy storage. Due to their large capacities, Borehole Thermal Energy Storage (BTES) systems are particularly suited for district scale solutions. The efficiency of those systems and their components is highly dependent on the implemented operational temperature levels. To quantify those interdependent and partially opposing effects, a numerical case study is carried out, in which a SDH system with BTES is integrated into an existing district heating grid. For this purpose, a coupled numerical simulation approach has been developed, in which the above- and below-ground parts of the system are considered each in dedicated software environments. The BTES is simulated using FEFLOW, a finite-element software tool, taking into account the specific geology of the site under investigation. The SDH is simulated in SimulationX, a system simulation suite based on Modelica, providing detailed information about energy supply, demand and losses of the grid and each component. 16 different scenarios for the grid and storage discharge temperatures are analyzed taking into account energetic, economic and ecological criteria. The results show that optimal solutions can vary considerably according to the weighting of objectives. Furthermore, the study reveals that the optimization of the overall system in a multi-objective approach is much more important than focusing on component efficiencies only. However, the results are highly sensitive to economic boundary conditions. Accordingly, the considered regulatory framework and energy prices are very important.

Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Earth Science
11 Department of Materials and Earth Sciences > Earth Science > Geothermal Science and Technology
Event Title: 10th European Geothermal PhD Day 2019
Event Location: Potsdam, Germany
Event Dates: 25.-27.02.2019
Date Deposited: 07 May 2019 05:49
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