An energy transition is required to face climate changes. A commitment from the government of the province of Quebec, in Canada, labelled as “l’exemplarité de l’État”, seek to reduce greenhouse gas (GHG) emissions of institutional building heating systems. In Quebec, the intensity of GHG emissions related to electricity consumption is relatively low. Electrification can thus contribute, in a certain way, to decarbonize heating. This transition presents numerous challenges, including electric demand management, since the province’s grid already peaks during the winter due to heating. The energy transition of building heating systems must therefore include different strategies, including demand management measures such as thermal storage. A sensible thermal energy storage system, a central electric thermal storage (ETS) device, is commercially available and designed for hydronic heating of institutional buildings. When demand allows, the ETS device converts electricity into heat and stores it in bricks. Heat is then extracted to meet heating load without significant impact on electric demand.
The main objective of this research project is to ease implementation of this ETS hydronic device in institutional buildings, more specifically in educational facilities administered by school boards. “Implementation” comprises design, commissioning, operation, and maintenance stages. In the literature as well as in the industry, barriers to adoption of thermal storage remain, hence the objective of easing implementation by proposing concrete ways to overcome those barriers.
To do so, the methodology used is mixed: in part qualitative and quantitative. The first part, qualitative, is to identify challenges faced and lessons learned from past implementations of the ETS hydronic device using semi-structured interviews with various industry stakeholders. The second part, quantitative, is to quantify the in situ performance of ETS hydronic devices using building operational data. This mixed method allows analyzing the effect of actual implementation practices on in situ performance, in a way to highlight best practices to adopt. Among those, elaboration of detailed control sequences during design stage plays a crucial role in the commissioning process and in reaching energy, economic, and GHG emissions reduction benefits. Indeed, analysis of operational data demonstrated a strong connection between in situ performance, reliability of control sequences in place, and ETS device’s operation tracking. On its hand, analysis of interviews outlined the challenge of having sufficient data at the design stage to develop detailed control sequences, even on heating and electric loads of existing buildings, and on the ETS hydronic device itself.
Based on the analyses of interviews and operational data, the third part of this research project is to propose solutions to improve actual practices and performance. Thus, data extracted from interviews on replaced ETS hydronic device’s components were used to summarize preventive maintenance tasks to complete in a sheet. This summary sheet purposes are to better plan maintenance actions and to avoid damageable operating modes for those components, while considering that allowable resources for maintenance are limited. Using operational data of ETS hydronic devices (80 kWe model), self-discharge was characterized by the effective heat loss coefficient and maximum thermal power output was quantified, both to support the elaboration of detailed control sequences at the design stage and operation tracking.
To follow up on this research project, it is recommended to develop automated tools easing implementation of the ETS hydronic device, such as: a simplified estimation tool to assess energy, economic, and GHG emissions impacts to support preliminary technical and economical analyses; an energy modelling tool to ease elaboration of detailed control sequences; and a tool to integrate fault detection and diagnostics system and energy management system to ease continuous operation and performance tracking, respectively. Finally, an analysis of benefit shares between consumers and public electric utilities, with for example modified tariffs or a demand-side management program including a common control strategy, should be considered to ease implementation of electric thermal storage and fast forward the energy transition of buildings.
| Date | 25 Apr 2023 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Katherine D'Avignon (Supervisor) |
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