Thermochemical Energy Storage Design in Improving Peak Shaving for District Heating System

Chung-Yu Yeh

Research output: ThesisEngD ThesisAcademic

Abstract

The Heatlands project is dedicated to investigating various aspects of thermal storage system implementation within 3rd and 4th generation district heating systems (DHs), with a specific emphasis on thermochemical energy storage (TCES) and the utilization of residual heat from industries. It aims to develop TCES systems to enhance DHs by providing additional buffer storage capacity and supporting peakload demand, thereby reducing reliance on fossil fuels and enhancing the overall sustainability of the DHs.
The EngD thesis details the progress and outcomes of a design project, starting with the procedure of stakeholder needs analysis. The key stakeholders encompass heat suppliers and heat grid operators for DHs in the Enschede areas, striving to phase out natural gas consumption, especially during peak heat demand periods. These local utilities’ ambition aligns perfectly with the Twente regional objectives outlined in the energy transition plan, which aims to steer the thermal sector towards a more sustainable energy system. The analyzed needs and desires of these stakeholders have transformed into design requirements centered around peak load reduction, energy system transition, and the robustness of heat supply.
Following analyzing the design requirements, the proposed design solution introduces a dual thermal storage system. This innovative approach combines existing hot water storage with TCES to address heat loss during prolonged storage periods. The configuration of this dual thermal storage system, particularly the TCES component, is thoroughly analyzed to ensure seamless integration with other DH components. This includes coordinating with a
cogeneration power plant (CHP) as the base load heat source and hot water storage as short-term storage to achieve the goals of reducing peak loads and enhancing energy efficiency. This dual thermal storage system is tailored in both scenarios of 3rd and 4th generation DHs from technical and economic perspectives (only in 4th DHs).
Apart from the focal point of reducing natural gas consumption, the design also encompasses the recovery and utilization of residual heat from industrial processes. One such valuable source is the excess heat generated by supermarket cooling systems. Due to its consistent availability and proximity, supermarkets emerge as prime candidates for DH applications in the Enschede region. The residual heat integration is considered in only 4th generation DHs due to the similarity of temperature level.
The results of these simulations suggest that 4th generation DHs are both technically and economically suitable for TCES implementation. Their ability to access low-temperature heat sources directly from the environment contributes significantly to this feasibility.
Additionally, the implementation of a weekly-based CHP supply can substantially reduce the mismatch between supply and demand, thereby aiding in peak load reduction. When combined with the TCES’s capability to store supermarket residual heat as a secure backup for peak loads, it becomes feasible for energy allocation for a long-term period. As a result, the finalized design solution involves incorporating two base load heat sources (CHP and residual heat) and a dual thermal storage system (hot water storage and TCES) within 4th generation DHs. To realize this concept, a TCES reactor prototype is devised based on key attributes derived from prior system-level analyses. The reactor employs a fixed bed with a U-shaped embedded heat exchanger tube, which is enhanced with
honeycomb metal fins to address heat transfer rate challenges commonly associated with closed-system TCES. The study also considers future implementation, risk management, and operational scenario tests as integral aspects of the development process.
Original languageEnglish
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Brem, Gerrit, Supervisor
  • Shahi, Mina, Supervisor
  • Mahmoudi, Amirhoushang, Co-Supervisor
  • Singh, Abhishek Kumar, Co-Supervisor
Award date16 Nov 2023
Place of PublicationEnschede
Publisher
Publication statusPublished - 16 Nov 2023

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