Periodic Reporting for period 2 - HyFlow (HyFlow: Development of a sustainable hybrid storage system based on high power vanadium redox flow battery and supercapacitor – technology)
Reporting period: 2022-05-01 to 2024-02-29
In the course of the energy transition, the European power grid must constantly adapt. Today's power grids require dynamic multi-time-scale energy storage systems due to the rise of renewables and their fluctuating electricity production. In addition, high consumption peaks are putting more and more stress on the grid.
The project HyFlow has tackled these challenges and developed a hybrid energy storage system consisting of a vanadium redox flow battery, a supercapacitor, advanced converter topologies and a highly flexible control system that allows adaption to a variety of system environments. Such a hybrid system guarantees a fast and flexible availability of electricity by managing load peaks of private and public grids as well as renewable energy production.
The storage system is capable of meeting high energy and high power demands using the advantages of both storage technologies. On the one hand, high-power vanadium redox flow batteries offer large storage capacities. Supercapacitors on the other hand, can accelerate the charging and discharging process significantly while increasing the lifetime of the overall system. The hybridization of these two high performing devices creates an energy storage system, fully integrated with both high storage capacity and high power and enables the operation on various time scales. The six objectives of HyFlow are summarized as following: HyFlow develops (1) high-power vanadium redox flow batteries, (2) green aqueous based supercapacitors with increased cell voltage, (3) advanced component management systems, and (4) discrete and optimised simulation models for each components. We demonstrate (5) adaptable management strategies at four different application scenarios by developing two demonstrators. In general, HyFlow (6) improves the ecologic sustainability of the high power vanadium redox flow battery and the supercapacitor. Technology like our demonstrators finds application in a wide range of storage systems and will have a high impact on climate change mitigation, which is of essential importance to socio-ecological aspects.
The project HyFlow has tackled these challenges and developed a hybrid energy storage system consisting of a vanadium redox flow battery, a supercapacitor, advanced converter topologies and a highly flexible control system that allows adaption to a variety of system environments. Such a hybrid system guarantees a fast and flexible availability of electricity by managing load peaks of private and public grids as well as renewable energy production.
The storage system is capable of meeting high energy and high power demands using the advantages of both storage technologies. On the one hand, high-power vanadium redox flow batteries offer large storage capacities. Supercapacitors on the other hand, can accelerate the charging and discharging process significantly while increasing the lifetime of the overall system. The hybridization of these two high performing devices creates an energy storage system, fully integrated with both high storage capacity and high power and enables the operation on various time scales. The six objectives of HyFlow are summarized as following: HyFlow develops (1) high-power vanadium redox flow batteries, (2) green aqueous based supercapacitors with increased cell voltage, (3) advanced component management systems, and (4) discrete and optimised simulation models for each components. We demonstrate (5) adaptable management strategies at four different application scenarios by developing two demonstrators. In general, HyFlow (6) improves the ecologic sustainability of the high power vanadium redox flow battery and the supercapacitor. Technology like our demonstrators finds application in a wide range of storage systems and will have a high impact on climate change mitigation, which is of essential importance to socio-ecological aspects.
The consortium designed the layout for both one lab-scale (5 kilowatts of power) as well as one industry-scale (300 kilowatts of power) demonstrator. For both of these hybrid energy storage systems, advanced power electronics and component management systems have been developed, designed and built. Supercapacitors, including the control system, were installed on the large demonstrator. The individual components of the small demonstrator were assembled, interconnected and successfully tested for their function. Several material improvements have been made to improve and optimize the battery modules of the redox flow battery with respect to enhanced power. Recycling strategies for Vanadium, the chemical core element in the battery, have been developed and a prototype for a vanadium extraction and recycling plant was constructed. There was also a strong fundamental development during the project to achieve supercapacitor carbon electrodes from a sustainable local source, instead of the typical activated carbon from coconut shells. One focus was on developing non-flammable, water-based electrolytes. This can reduce the carbon footprint of the new system by up to 40 per cent and its cost by up to 60 per cent compared with Li-ion batteries.
Discrete simulation models of all components have been verified with real application data and are part of the HyFlow strategy. The possible use of hybrid energy storage systems in off-grid systems were also subject. The energy management system developed in the project can read and interpret information from the individual storage components such as battery, converters or the supercapacitor management system and control the hybrid system intelligently to achieve a high degree of energy autonomy. The smart switching of the two storages can increase the lifetime of components such as pumps by more than 2 years. The time-scale both demonstrators can cover is very broadly diversified and reaches from milliseconds up to days.
Major exploitable results include: Filing of one patent, new development of a fully commercialized product and the successful application for the follow-up project “SMHYLES” within the Horizon Europe programme, where four HyFlow members are involved.
Discrete simulation models of all components have been verified with real application data and are part of the HyFlow strategy. The possible use of hybrid energy storage systems in off-grid systems were also subject. The energy management system developed in the project can read and interpret information from the individual storage components such as battery, converters or the supercapacitor management system and control the hybrid system intelligently to achieve a high degree of energy autonomy. The smart switching of the two storages can increase the lifetime of components such as pumps by more than 2 years. The time-scale both demonstrators can cover is very broadly diversified and reaches from milliseconds up to days.
Major exploitable results include: Filing of one patent, new development of a fully commercialized product and the successful application for the follow-up project “SMHYLES” within the Horizon Europe programme, where four HyFlow members are involved.
In the future, hybrid storage systems will play a very important role in expanding redox flow systems to markets that are dominated by lithium-ion storage systems. The combination of supercapacitorand high-power vanadium redox flow batteries creates a very competitive energy storage system that avoids the usage of critical raw materials and can even beat lithium-ion storage in some areas. The advantages of a hybrid energy storage system, namely the ability to vary the size of the powerful supercapacitor, the capacity of the tank and the power of the redox flow battery independently of each other, allow a storage package to be put together precisely for the respective application scenario. The modular storage design in turn enables a very efficient system and saves unnecessary costs in the event of oversizing. Long-term storage and the coverage of the consumer's base load covers the redox flow battery, while the supercapacitors as a power component handles high short-term demands. This achieves higher grid independence, a more stable grid and a larger degree of autonomy. The logic of the energy management system developed for the laboratory demonstrator can be easily integrated into other hybrid storage systems. Its simple scalability and optimizability allows for an overall hybrid system that can be adapted to the continuously changing market requirements. The experimental data generated by the two lab- and industry-scale demonstrators was used to derive models and algorithms for the energy management system development and the optimization of the vanadium redox flow battery and supercapacitor components.
A next step in the future of low-cost and environmentally friendly energy supply beyond the scope of the project can be to replace the vanadium electrolyte from the developed high-power redox flow battery with higher available alternatives such as iron. Switching to a different electrolyte has many advantages: Iron is considerably cheaper. It does not have to be imported as a raw material, as it is available in practically every country. You are independent of the political conditions in other countries and can use your own, more sustainable extraction methods. Iron as an electrolyte also contains no strong acids. This means that the storage system is easier to maintain and the electrolyte is much easier to dispose of at the end of life.
A next step in the future of low-cost and environmentally friendly energy supply beyond the scope of the project can be to replace the vanadium electrolyte from the developed high-power redox flow battery with higher available alternatives such as iron. Switching to a different electrolyte has many advantages: Iron is considerably cheaper. It does not have to be imported as a raw material, as it is available in practically every country. You are independent of the political conditions in other countries and can use your own, more sustainable extraction methods. Iron as an electrolyte also contains no strong acids. This means that the storage system is easier to maintain and the electrolyte is much easier to dispose of at the end of life.