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HyFlow: Development of a sustainable hybrid storage system based on high power vanadium redox flow battery and supercapacitor – technology

Periodic Reporting for period 1 - HyFlow (HyFlow: Development of a sustainable hybrid storage system based on high power vanadium redox flow battery and supercapacitor – technology)

Período documentado: 2020-11-01 hasta 2022-04-30

Fluctuations of renewable generation as well as load peaks influence modern energy grids. In order to absorb those power peaks, today's power grids depend on more dynamic multi-time-scale energy storage systems. The project HyFlow is meeting these challenges with the development of a Hybrid Energy Storage System (HESS). The system guarantees the fast and flexible availability of electricity by managing load peaks of private and public grids as well as renewable energy production. It will be capable of meeting high energy and high power demands using two storage technologies: On the one hand, high-power vanadium redox flow batteries (HP-VRFB) offer large storage capacities. Supercapacitors (SC), 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 solutions creates an energy storage system, fully integrated with both high storage capacity and high power and enables the operation on various time scales. HyFlow focuses on technological and ecological improvements of the HESS components, their management systems and their interaction. The main goal is to adapt and enhance storage components for optimal hybridization. The results will contribute to a sustainable, cost effective and highly flexible electricity grid. The six objectives of HyFlow are summarized as following. HyFlow will develop (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 will (5) demonstrate adaptable management strategies for at least four different application scenarios by developing two demonstrators. In general, HyFlow (6) improves the ecologic sustainability of the HP-VRFB and the SC. The outcomes of HyFlow will contribute to the ambitious goals of the European Green Deal by addressing the issues of carbon neutrality and climate resilience. The developed system will enable the usage of affordable and clean energy. Our technology will have a high impact on climate change mitigation, which is of essential importance to socio-ecological aspects.
Up to now, the research focus is set on the development of advanced components and component management systems. Improved materials for high-power vanadium redox flow batteries (HP-VRFB) lead to further development of the cell and stack performance. Compared to the status quo, the consortium already achieved up to 60 % higher current densities within lab cells. HyFlow aims to improve the ecologic sustainability of the storage components. The consortium works during the project on a new environmentally friendly supercapacitor (SC). A first cell demonstrator has been developed based on a sustainable manufacturing process and the usage of green, locally available raw materials. The cell prototype aims at a higher cell voltage above 1.5 V and an increase of the specific energy density of 45 %. Recycling strategies for vanadium, the main part of the HP-VRFB, have been developed and a prototype for a vanadium extraction and recycling plant was constructed. Life cycle assessment (LCA) applying ISO 14040/14044 methodology is being constantly developed based on the data provided by all beneficiaries.

Advanced management systems for both components, are the core control mechanisms for the operating and safety concepts of the HESS. On the one hand, both storage components, the HP-VRFB and the SC, require adaptable control strategies to meet the energy demand while maintaining safety operation modes. On the other hand, the Energy Management system (EMS) controls the complete HESS taking into account the application scenario. Thus, the EMS predicts all power demands and adapts the power flow between the components. Discrete simulation models of all components verified with real application data are one essential part of the HyFlow strategy. Up to now, all components can be simulated with a simulation error of less than 5 %.

Moreover, the consortium defined the layout for both the lab-scale (5kW) as well as the industry-scale (300kW) demonstrator. Up to now, the electrical layout of the lab-scale demonstrator give first indications on potential efficiency improvements reduced installed converter power and adaptable communication between the components. The demonstrators will be installed to test the aforementioned components, their performance and control algorithms as well as the interaction of the complete HESS. The consortium defined four different load scenarios. High power peak (1) and weak distributions grids (2) are suitable application cases. Typical applications include different scenarios, where SC or batteries are already used, and which could benefit from an additional energy component to make the system more efficient or the application of renewable energy more useful. Moreover, the HESS can meet the flexible requirements of uninterruptible power supply (3) for sensitive infrastructure, e.g. telecommunication, and momentary reserve (4). The HESS can deliver a more adjusted, optimized and compact storage system for these applications. The load data evaluation lead to a first definition of component roles in HESS. In general, the HESS will be able to cover time scales from milliseconds up to several hours.
Developing low-cost energy storage systems is a central pillar for a secure, affordable and environmentally friendly energy supply based on renewable energies. In demanding applications, hybridization leads to more efficient storage systems, with longer lifetime as well as higher adaptability and potentially lower costs. The hybrid system avoids the usage of critical raw materials, thus ensuring environmentally friendly operation. HyFlow forms a unique opportunity for both research and industrial stakeholders in order to develop tailor-made solutions and to explore new markets. By combining the best of both worlds, a supercapacitor (SC) and a high-power vanadium redox flow battery (HP-VRFB), this solution will unlock numerous applications in the grid, boosting its stability while decreasing the dependence on fossil fuel. The system design enables modular long-term energy storage through HP-VRFB, while the SC as a power component handles high load demands. The flexible Energy Management System (EMS) will be designed to perform high level of control and adaptability using computational analysis and hardware development. Newly developed simulation models of all components can be scaled to higher powers and show the performance of the HESS in different application scenarios. The consortium will build upon lab- and industry-scale experimental data to derive models and algorithms for the EMS development and the optimization of existing HP-VRFB and SC components. Outputs of the project support the whole value-chain and life cycle of HESS by developing new materials and components and adding them together with an innovative EMS. The development of the HESS, especially the flexible EMS, enables plethora usage potentials. It will lead to the grid integration of the HESS where the full flexibility can be achieved and optimized for market requirements.