Periodic Reporting for period 3 - CHESTER (Compressed Heat Energy Storage for Energy from Renewable sources)
Berichtszeitraum: 2021-04-01 bis 2023-03-31
Electricity storage has a key role in the transition of the European energy sector towards a neutral emissions system. Balancing the grid is mandatory in order to allow for the targeted RES penetration in the grid. Energy storage will be the key enabling technology for increasing RES production in the future.
CHESTER project aims to develop a CHEST (Compressed Heat Energy Storage) system, an innovative power-to-heat-to-power energy storage system. It delivers heat and power on demand, making use of the excess renewable and other excess energy sources available. The combination of the CHEST system with Smart District Heating or other thermal loads (.e.g. industries) leads to a very flexible and smart renewable energy management system that is able to efficienctly store electric energy, site-independent unlike pumped hydro, cyclically stable unlike batteries, able to convert power into heat, able to convert renewable low temperature heat into power, able to store and deliver independently from each other upon request both, heat and power, cost competitive.
The CHESTER project overall objectives are mainly two: to demonstrate a first-of-its-kind laboratory scale prototype system (10 kWe) and advance from TRL3 to TRL5 on system concept at real scale regarding system design and optimization, and integration into the grid and electric market.
CHESTER project aims to develop a CHEST (Compressed Heat Energy Storage) system, an innovative power-to-heat-to-power energy storage system. It delivers heat and power on demand, making use of the excess renewable and other excess energy sources available. The combination of the CHEST system with Smart District Heating or other thermal loads (.e.g. industries) leads to a very flexible and smart renewable energy management system that is able to efficienctly store electric energy, site-independent unlike pumped hydro, cyclically stable unlike batteries, able to convert power into heat, able to convert renewable low temperature heat into power, able to store and deliver independently from each other upon request both, heat and power, cost competitive.
The CHESTER project overall objectives are mainly two: to demonstrate a first-of-its-kind laboratory scale prototype system (10 kWe) and advance from TRL3 to TRL5 on system concept at real scale regarding system design and optimization, and integration into the grid and electric market.
EXPERIMENTAL WORK AT LABORATORY SCALE:
The CHEST system is formed by a high temperature heat pump (HTHP), a high temperature thermal energy storage (HT-TES) and an ORC unit. Electricity is consumed by the HTHP and the produced heat is stored in the HT-TES, to be used later on by the ORC unit and produce electricity. In addition, a novel heat engine (based on isobaric expansion (IE)) has been developed in order to increase cycle efficiency if integrated into the system.
The HTHP, HT-TES, heat engine and ORC prototypes were designed, manufactured and individually characterized at responsible partners’ laboratory:
• A 10kWe HTHP that uses an environmentally friendly refrigerant (R1233zd(E)) able to operate at high evaporating temperatures (70ºC to 95ºC) and high condensing temperatures (approximately 146ºC) has been built and tested. Measured COP values ranging from 3 to almost 7 were achieved.
• A novel design of a HT-TES system based on PCM has been developed and prototype built (melting temperature of the selected PCM is 133ºC). The system is formed by a latent heat storage unit (LT-TES) of 2,1 m3 and a sensible heat storage unit (SH-TES) of 2 m3.
• A novel ORC prototype has been built, commissioned and tested, including an over 10 kWe nominal power piston expander with a built-in novel variable valve timing mechanism. Experimental results demonstrate the advantageous implementation of the real time control of the expander inlet valve timing to increase the efficiency of the prototype.
• A novel isobaric expansion heat-engine pump prototype has been successfully built, commissioned and tested. Experimental results demonstrate the great potential of IE engines as a technology for conversion of heat to mechanical energy, particularly in low temperature applications.
In the last stage of the project the individual prototypes have been integrated into the whole CHEST prototype and tests were carried out both as full and as partial cycles to investigate the system performance. The results show that the theoretical concept of Compressed Heat Energy Storage for Energy from Renewable sources (CHESTER) works successfully at a laboratory scale. Based on the experimental results, estimations for large scale CHEST systems have been made, concluding that roundtrip efficiencies in the range of 68% would be attainable based on the current prototypes and identified optimizations.
THEORETICAL WORK TO ADVANCE ON THE CHEST CONCEPT:
One of the objectives of the CHESTER project is to establish the theoretical basis for the upscaling and optimization of the CHEST system. After five years of research in the CHESTER project with plenty of results from experiments, market potential and business model opportunity studies, the consortium has drawn the major conclusions and established a roadmap to outline the current and future potential applications of the Compressed Heat Energy Storage (CHEST) system.
An interesting business case study was found for an Eco-Industrial Park in Denmark. This kind of application, which combines the storage of both heat and electricity, makes the best use of the CHEST concep and engages several revenue streams, resulting in a positive business model already at MW scale, with a return on investment within 5 to 6 years for the analyzed boundary conditions.
The CHESTER consortium has also analysed the determining factors for obtaining a good economy with the use of the CHEST system, and identified the following:
• Effort needs to be made to reduce the investment cost of the Latent Heat Thermal Energy Storage (LHTES)
• Favourable taxation on electricity
• High load and long operating hours of the system
• Excess of electricity and/or heat availability/mutualised (sector coupling)
A general conclusion of the techno-economic studies is that the CHEST system is well suited for sector coupling and is likely to fit into the energy systems of the future, where renewables have a higher penetration into the energy system (both heat and electricity production).
The CHEST system is formed by a high temperature heat pump (HTHP), a high temperature thermal energy storage (HT-TES) and an ORC unit. Electricity is consumed by the HTHP and the produced heat is stored in the HT-TES, to be used later on by the ORC unit and produce electricity. In addition, a novel heat engine (based on isobaric expansion (IE)) has been developed in order to increase cycle efficiency if integrated into the system.
The HTHP, HT-TES, heat engine and ORC prototypes were designed, manufactured and individually characterized at responsible partners’ laboratory:
• A 10kWe HTHP that uses an environmentally friendly refrigerant (R1233zd(E)) able to operate at high evaporating temperatures (70ºC to 95ºC) and high condensing temperatures (approximately 146ºC) has been built and tested. Measured COP values ranging from 3 to almost 7 were achieved.
• A novel design of a HT-TES system based on PCM has been developed and prototype built (melting temperature of the selected PCM is 133ºC). The system is formed by a latent heat storage unit (LT-TES) of 2,1 m3 and a sensible heat storage unit (SH-TES) of 2 m3.
• A novel ORC prototype has been built, commissioned and tested, including an over 10 kWe nominal power piston expander with a built-in novel variable valve timing mechanism. Experimental results demonstrate the advantageous implementation of the real time control of the expander inlet valve timing to increase the efficiency of the prototype.
• A novel isobaric expansion heat-engine pump prototype has been successfully built, commissioned and tested. Experimental results demonstrate the great potential of IE engines as a technology for conversion of heat to mechanical energy, particularly in low temperature applications.
In the last stage of the project the individual prototypes have been integrated into the whole CHEST prototype and tests were carried out both as full and as partial cycles to investigate the system performance. The results show that the theoretical concept of Compressed Heat Energy Storage for Energy from Renewable sources (CHESTER) works successfully at a laboratory scale. Based on the experimental results, estimations for large scale CHEST systems have been made, concluding that roundtrip efficiencies in the range of 68% would be attainable based on the current prototypes and identified optimizations.
THEORETICAL WORK TO ADVANCE ON THE CHEST CONCEPT:
One of the objectives of the CHESTER project is to establish the theoretical basis for the upscaling and optimization of the CHEST system. After five years of research in the CHESTER project with plenty of results from experiments, market potential and business model opportunity studies, the consortium has drawn the major conclusions and established a roadmap to outline the current and future potential applications of the Compressed Heat Energy Storage (CHEST) system.
An interesting business case study was found for an Eco-Industrial Park in Denmark. This kind of application, which combines the storage of both heat and electricity, makes the best use of the CHEST concep and engages several revenue streams, resulting in a positive business model already at MW scale, with a return on investment within 5 to 6 years for the analyzed boundary conditions.
The CHESTER consortium has also analysed the determining factors for obtaining a good economy with the use of the CHEST system, and identified the following:
• Effort needs to be made to reduce the investment cost of the Latent Heat Thermal Energy Storage (LHTES)
• Favourable taxation on electricity
• High load and long operating hours of the system
• Excess of electricity and/or heat availability/mutualised (sector coupling)
A general conclusion of the techno-economic studies is that the CHEST system is well suited for sector coupling and is likely to fit into the energy systems of the future, where renewables have a higher penetration into the energy system (both heat and electricity production).
CHEST system:
- Before the start of the project there was not any realized system of CHEST concept and very little knowledge available regarding the concept itself. The performed work has allowed to establish the theoretical basis of the performance of full scale CHEST system on real applications and an advanced model has been developed which comprises a relevant tool for further research and development.
HT-TES based on PCM:
- Innovative heat storage design based on a cascaded unit with sensible and latent storage allowing high efficiency in condensing/evaporating processes. Prototype for 133ºC melting temperature in the range of several m3 designed, built and characterized. PCM heat exchanger based on aluminium finned tubes. PCMs storage design for new working fluids.
HTHP:
- Compressor, using an alternative refrigerant with low GWP, successfully tested allowing refrigerant outlet temperatures >150ºC.
- Selection and use of the most appropriate lubricant that ensures the compressor operation and durability based on experimental characterization
ORC:
- Improve standard technology of expanders, including a variable volume ratio mechanism with a sliding volume valve (never used so far in expanders)
HEAT ENGINE:
- Novel heat engine pump based on isobaric expansion of 1 kW output designed, built and tested. Demonstration of effective operation at heat source temperature of <80ºC.
SEMS
- Implementation of forecasting models into control strategies. Advanced AI-based control system that is scalable and portable. A self-learning dynamic management tool based on AI algorithms in order to control and optimize the operation of the CHEST system.
All the technologies have been integrated into the overall CHEST system and the whole prototype's operation tested. First-of-its kind CHEST prototype has been operated and operational experience gained.
- Before the start of the project there was not any realized system of CHEST concept and very little knowledge available regarding the concept itself. The performed work has allowed to establish the theoretical basis of the performance of full scale CHEST system on real applications and an advanced model has been developed which comprises a relevant tool for further research and development.
HT-TES based on PCM:
- Innovative heat storage design based on a cascaded unit with sensible and latent storage allowing high efficiency in condensing/evaporating processes. Prototype for 133ºC melting temperature in the range of several m3 designed, built and characterized. PCM heat exchanger based on aluminium finned tubes. PCMs storage design for new working fluids.
HTHP:
- Compressor, using an alternative refrigerant with low GWP, successfully tested allowing refrigerant outlet temperatures >150ºC.
- Selection and use of the most appropriate lubricant that ensures the compressor operation and durability based on experimental characterization
ORC:
- Improve standard technology of expanders, including a variable volume ratio mechanism with a sliding volume valve (never used so far in expanders)
HEAT ENGINE:
- Novel heat engine pump based on isobaric expansion of 1 kW output designed, built and tested. Demonstration of effective operation at heat source temperature of <80ºC.
SEMS
- Implementation of forecasting models into control strategies. Advanced AI-based control system that is scalable and portable. A self-learning dynamic management tool based on AI algorithms in order to control and optimize the operation of the CHEST system.
All the technologies have been integrated into the overall CHEST system and the whole prototype's operation tested. First-of-its kind CHEST prototype has been operated and operational experience gained.