The production of high-performance batteries consumes an enormous amount of energy, especially for cooling and heating. The Fraunhofer Research Facility for Battery Cell Production FFB in Münster has been able to reduce its consumption in this area by up to 40 per cent thanks to a highly efficient com-bined heat pump.
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Fraunhofer FFB is setting up a research facility for efficient and sustainable battery cell production at the Münster site, creating a centre for the development of modern battery cell production. The establishment will create a unique infrastructure that will transfer cutting-edge technologies and expertise to industry. In the first factory, the "FFB PreFab", a sample line for complete battery cell production on a smaller scale will be set up on around 3000 m², followed by the "FFB Fab", a research facility on a gigantic scale. In order for the research factories and future European battery cell factories to make a positive contribution to climate protection, their enormous energy requirements must be considered.
Together, the "FFB PreFab" and the "FFB Fab" will have a total energy requirement of around 120 gigawatt hours (GWh) per year. This corresponds to the demand of around 6,000 single-family homes. For commercially utilised gigafactories, which have continuous production compared to the research factory, this value is around 15 times higher. A not insignificant proportion of around 60 % of this is the demand for cooling and heating. A small proportion of this is required for cooling the manufacturing process. However, most of the cold and heat is used for dehumidification in order to create ambient conditions that are drier than in any desert. This is because the materials in a lithium-ion battery react to even the slightest amount of moisture and the relative humidity must not exceed 0.05%. The air is dried using dehumidification technology that always requires cold and heat at the same time due to its cooling and heating coils. The temperature level of the conventional dehumidification flow is 130 °C to 160 °C.
The heat requirement can be provided either conventionally using natural gas or with the help of electric heating systems. The use of heat pumps is more efficient. However, the necessary 130-160 °C cannot be achieved with these, as the water in the heating system vaporises at 100 °C and above. For this reason, Fraunhofer FFB uses a highly efficient dehumidification technology with three dehumidification rotors connected in series, which requires maximum temperatures of 85 °C. This works with high-temperature heat pumps. This works with high-temperature heat pumps. However, as there is always a very high cooling requirement at the same time, it makes sense to use a combination heat pump. This combination of simultaneous generation of high-temperature heat and cooling is a fairly new development. And so the system type in the "FFB PreFab" and the "FFB Fab" with its high performance class is almost unique in Europe.
The system generates cooling and heat simultaneously by using the waste heat from cooling as a source for the two-stage high-temperature heat pump. This coupling enables coefficients of performance of up to 8 to be achieved. This means that one kilowatt of electrical power for operating the heat pump generates 8 kW of thermal power.
Low-temperature combined heat pumps are used at the Fraunhofer FFB in Münster to supply the building heating system, which also generates the required cooling at the same time.
Overall, the highly efficient simultaneous provision of cooling and heating is not only interesting for the Fraunhofer FFB and battery cell production in general, but for every other institute and every other industry that has a simultaneous cooling and heating requirement.
We are also happy to support other institutes within external projects in the creation of efficient and sustainable energy concepts and in examining the possibility of using a combined heat pump with subsequent planning and design.
Editor's note: This article was first published in the Fraunhofer employee magazine "Quersumme", written by Dr. Birgit Ziller.
Fraunhofer Research Institution for Battery Cell Production FFB