Flexible Sector Coupling (FSC) of Electrical and Thermal Sectors via Thermal Energy Storage (TES) - A Case Study on Oskarshamn Energi

Background

Sector Coupling (SC) is increasingly approached today to meet the global climate demands in particularly the energy sector, to make the best use of intermittent renewable energy sources while cutting down on fossil fuels and nuclear power. SC can merge and balance surpluses of one energy stream with the demands in another. Intermittent renewables like solar and wind often experience a risk for curtailment at their peak production when the existing electrical grid capacities are limited. The global power and thermal energy requirements are ever increasing, and still met for the major part via fossil fuels and nuclear. With more than 50% of global primary energy taken up by heating and cooling [1], thermal sector, including district heating (DH) and district cooling (DC), is undeniably a key energy sector.

Interestingly, DH and DC can absorb the intermittent surcharges of electricity adopting power-to-heat and power-to-cold, when smartly integrated and operated with thermal energy storage (TES) coupled with e.g., heat pumps and chillers (and like). With TES, flexibility is added to both electrical and thermal sectors, accomplishing flexible sector coupling (FSC). Even if this sounds like a remarkable synergy, it appears that the current market and infrastructures of these sectors may be limited to extract optimal benefits from the opportunities in FSC. One key limitation might be that the design and optimization of the two sectors typically happen in isolation, with very little interaction (for lacking financial incentives for their integration), and without considering the flexibility synergies rendered by coupling the two sectors via TES. Therefore, truly holistic design and analysis of FSC between electrical and thermal sectors appear to be limited today.

Task description

Within this background, this project aims to evaluate the options for FSC between electrical and thermal sectors by means of TES, and related conversion technologies, via techno-economic analyses. This is expected to be done preferably using open access software tools, e.g. OSeMOSYS[1] [2] together with a dispatch model (that could be programmed in e.g. Python or like, or with EnergyPlan[2] [3]) through a soft link approach. This is up for discussion and can be decided during the first phase of the project. The scope will be mainly on an energy company in Sweden: Oskarshamn energi AB, for their existing DH and electrical energy systems catering to Oskarshamn municipality, as a case study. Oskarshamn Energi AB [4] operates together with the daughter company Oskarshamn Energi Nät AB. The company is co-owned by the city of Oskarshamn and E.ON. Oskarshamn Energi caters today to the electricity (both supply and distribution), district heating as well as some of the mobility fuel (i.e., in fuel stations) demands in Oskarshamn. Their electricity and DH production is done via 3 production plants (marked 1, 2, and 3 in Figure 1), with one combined heat and power (CHP) unit and several heat only boiler (HoB) units, as summarized in Table 1.

Figure 1. Oskarshamn Energi AB’s three energy production plants location, numbered 1, 2 and 3

Table 1. Oskarshamn Energi’s electricity & heat production (CHP: Combined Heat & Power, HoB: Heat only Boiler)

1OSeMOSYS is a capacity investment model – Long term planning
2 EnergyPLan is a unit commitment dispatch model- technical and market simulation

• The project is for 2 students
• The project can be done from Stockholm (and online) mostly, with a few times’ physical presence at Oskarshamn energi as well.

Learning outcomes

• Explain flexible sector coupling (FSC) concept as applied to thermal and electrical energy systems and the role of thermal energy storage therein, and contrast FSC versus sector coupling
• Perform comprehensive review mapping out and comparing the available methods and tools on FSC analysis of electrical and thermal (DHC) sectors with TES, HPs, chillers, and like (considering Swedish and international literature)
• Identify suitable numerical methods and tools for techno-economic simulation and optimization of energy systems and their interactions, also with (and without) thermal energy storage
• Perform a case study analysis highlighting the technical, operational, economic and other opportunities in FSC between electrical and thermal sectors (using TES, HPs and like) in the chosen system, by considering supply-demand optimization as well as dispatch and grid aspects, for reasonable time resolutions and durations
• Future scenario assessment for techno-economic evaluation of e.g. the implementation of TES, HPs, and even new boilers (as the typical alternative), also considering power and DH demand and production pattern variations
• Critically appraise and discuss the numerical modelling results contrasting today’s system to future scenarios, as well as contrasting the employed tools against other available alternatives
• Draw key specific conclusions and recommendations to enable future development planning of the studied energy system as well as reflect on future work that can improve the study
• Propose generic conclusions and recommendations therein concerning FSC in this context and the available tools

Expected Steps

• A literature review (with critical discussion) on available methods and tools on FSC analysis of electrical and thermal (DHC) sectors with TES, HPs, chillers and like (in both Swedish and international contexts)
• Modelling the existing case study system (for available data of the thermal and electrical systems) using the chosen software approaches e.g., OSeMOSYS and the dispatch model (own/EnergyPlan etc.) respectively.
• Performing dispatch modelling e.g. through soft link approach using outputs from OSeMOSYS as inputs for the dispatch model (based on the final choice of tools)
• Formulating suitable possible future scenarios to incorporate e.g. TES, HPs, and even additional boilers (as the typical options), as well as electrical and heating demand and production pattern projections
• Developing the corresponding future scenario models in the chosen software tools and performing simulations
• Therein, explore possible flexibility synergies between these energy systems for FSC with TES and related technologies.
• Critically discuss the results for specific and generic conclusions and recommendations, on the opportunities, benefits and even barriers in FSC of electrical and thermal sectors with TES and related technologies.
  • Additional critical reflections on: 1) the obtained techno-economic results and their relevance to Oskarshamn energi’s energy system optimization and development, and 2) the used software tools as compared to other relatively new open access alternatives (e.g. DHNx [5], among others)

Prerequisites

• Mechanical/Chemical/Energy/Environmental engineering or like
• The knowledge and experience on numerical modelling tools like Python/Matlab and/or the tools stated in the proposal is an added advantage (but not compulsory)

Research Area/specialization/track

Sustainable energy Utilization / Solar energy (at the division of Applied Thermodynamics and Refrigeration)

Duration

• Typically 20 weeks (and maximum 24 weeks) of full-time work
• Expected start: January 2023 (negotiable)

How to apply

Send your application with the following documents by email to Saman Nimali Gunasekara 

1. CV
2. A cover letter explaining why you think you are suitable for this project
3. Bachelor’s degree academic transcripts
4. Master’s degree academic transcript so far

Upon evaluating these documents, you may be called for an informal interview (could be done online).

Supervisors and Examiner

Main supervisor at KTH:

Company supervisor at Oskarshamn Energi:

Mr. Johan Turesson

Co supervisors at KTH:

Examiners:

References