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Next-generation battery storage
Lithium-ion rechargeable batteries are our everyday companions and now found in all kinds of appliances, including mobile devices like smartphones, eBikes and household and consumer electronics. Their purposes span from A for automotive to Z for zapper. But what about batteries that are as big as a shipping container? Well, the electricity grid of the future needs this type of large-scale storage facility.
Developing them is important and they are at the centre of research projects including those conducted in the Next-MeBa Living Lab of the Energy Transition. The goal of the researchers is to make advances towards a broader use of battery storage facilities in the electricity system; ranging from batteries in the 100 kilowatts (kW) category to those with a megawatt capacity. They are to enable a more flexible, low-cost and stable power supply. The goal is to make these large-scale storage facilities more efficient, durable, affordable and safe.
Large-scale battery storage facilities as a key to a flexible electricity system
Large-scale lithium-ion batteries can take up electricity from renewables at times when wind or solar installations generate more energy than is needed at that moment. When the electricity is needed at a later point, it can then be fed back into the grid. In this way, these modern battery systems help to accommodate fluctuations in the power supply, stabilise the grid and make more efficient use of renewable energy. Photovoltaics (PV) is a great example of this: solar cells generate electricity in daylight and sunshine, which is then stored in a battery and released over night. If all components are ideally adjusted to one another, a large PV installation combined with a battery can yield green electricity 24/7, at least during the summer months.
New technical concepts for battery systems
The research team at next-MeBA focuses on three main goals: lowering costs, increasing life spans, and improving the safety of large-scale lithium-ion storage facilities. For this purpose, the researchers develop new systems architectures, more precise control mechanisms for individual battery cells and innovative safety concepts. A special modular concept is to prevent any possible battery failures or errors from spreading from one battery cell to others. The LiFEPO4battery chemistry reduces potential fire hazards for large-scale battery storage systems to a level no higher than that of conventional industrial buildings.
But the real key enabling technology is found in the inverter, which individually controls each battery cell, allowing the system to be operated in a highly efficient way – even in partial load –, with reduced waste heat and a longer operational life. For the first time, the project is scaling up this inverter technology beyond 100 KW and 250 kW, into the megawatts range. This AC battery will generate three-phase alternating current (also called polyphase current) directly.
Furthermore, the researchers are also seeking to increase battery cells’ durability and to develop low-cost solutions for the necessary cooling and systems technology. A digital twin of the large-scale storage facility is to help optimise its operations. Parallel to this, the project team is analysing potential use profiles and economic applications that are in line with the needs of the energy market and the electricity system.
Research for the future energy system
Initial tests on battery cells and safety components have already been successful. To conclude the project, several storage units with a capacity in the megawatts range are to be subjected to field tests to study the technology and use cases in a real-life environment and to prepare for the certification procedure for application in the medium voltage grid.
Cell characterisation, safety assessments, durability tests and simulations and a model of installation ageing – these are all points on the to-do list of the researchers at the Centre for Solar Energy and Hydrogen Research Baden-Wuerttemberg (ZSW) who work in the Next-MeBa Living Lab of the Energy Transition. The institute for energy conversion and storage at Ulm University is developing these innovative procedures and switches for these battery storage facilities with a capacity in the megawatts range. The project’s industrial partners are SAX Power GmbH and Proteba GmbH.
The Next-MeBa project, which receives funding from the Federal Ministry for Economic Affairs and Energy, is to continue until the end of 2027. The insights gained from this Living Lab of the Energy Transition are to help bring the next generation of large-scale battery storage facilities to market-readiness, thereby supporting the transition of the energy system towards a climate-neutral power supply. The Living Labs of the Energy Transition, a funding measure of the Federal Ministry for Economic Affairs and Energy, are designed to test innovations in a real-life environment.