Delivering district energy for a net zero society

Millar, Michael-Allan (2022) Delivering district energy for a net zero society. PhD thesis, University of Glasgow.

Abstract

District energy systems have been hailed as the cornerstone of any Net Zero carbon energy system, yet there are still distinct operating and design challenges in implementing an efficient and economic system. The novelty of this thesis therefore lies in attempting to providing routes to efficient district energy systems. Many dwellings will be uneconomical to connect to a heat network without significant investment to improve building fabric. This is demonstrated using dynamic modelling of common UK building stock. Transient System Simulation Tool (TRNSYS) is used to demonstrate the criticality of good building fabric on the potential to reduce operating temperatures in district energy networks, and therefore improve the overall system efficiency. It was shown that improving building conditions alone could offer a 30% reduction in space heating energy consumption, while building improvements and heat pumps could see a 70% reductions 5th generation energy networks are considered. Detailed building energy simulation modelling is given to identify indicative heating and cooling profiles of common building types which are then programmed to a linear optimization to identify the benefits of an energy sharing network. Key performance indicators are identified. This is of increasing importance as network designers begin to grapple with energy sharing network design considerations. The work showed the potential to reduce the levelised cost of energy by 69%, and carbon emissions by 13%. The critical finding however, was that thermal energy storage has the largest impact on energy sharing capability. To further validate the key performance indicator concepts, a more detailed non-linear optimization is given which discusses in greater detail the role of operating temperatures and flowrates on the system design. It was shown that traditional metrics become disconnected from ambient loop networks (e.g. linear demand density). The overall conclusions of the thesis show that although heat networks have suffered poor performance in the past, there are clear paths to improve this. However, this depends on choosing the correct connections to the network and understanding how to optimize for retrofit demands.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Yu, Prof. Zhibin
• Date of Award: 2022
• Depositing User: Theses Team
• Unique ID: glathesis:2022-82897
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 24 May 2022 10:26
• Last Modified: 24 May 2022 10:30
• Thesis DOI: 10.5525/gla.thesis.82897
• URI: https://theses.gla.ac.uk/id/eprint/82897

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