Due to the increasing proportion of renewable energies in the power grid, energy storage systems are gaining importance to ensure stable power supply. Today’s use of battery storage systems is associated with high costs. Apart from investment costs, operation costs also play an important role.

At the Energy Lab 2.0, a large-scale energy research facility at KIT, a close-to-production prototype of a large lithium-ion storage system with very low operation and maintenance costs is now being implemented. The efficient control system required for this purpose was developed by KIT’s Battery Technical Center. In addition, cooling of the prototype was optimized. Besides cooling water from geothermal probes, a concrete shell is used for passive cooling. Proper cooling increases the service life of batteries and, hence, economic efficiency. The new storage system supplies 1.5 MWh of usable energy and can reach an electric power of up to 800 kW. Optimal operation is ensured by two independent battery and inverter systems. They enable continuous operation of the storage system even if one of the components fails. As part of the building is located underground, the space needed for the battery storage system is reduced. An attractive design enhances acceptance by local population when used within urban spaces.

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Electrode foils play a decisive role in the production of batteries and accumulators for electric cars, smartphones, and laptops. The electrode material is applied as a thin paste to a copper or aluminum foil, with the electrode patterns being separated by small strips of uncoated foil serving as electrode conductors. To produce these uncoated areas, the coating process has to be stopped and restarted again. This takes a lot of time and increases production costs.

Researchers at KIT are now able to significantly increase production speed with a new intermittent, i.e. interrupting, process. They use a patented nozzle equipped with a special membrane which is able to interrupt the coating process abruptly and to restart it again. As no other moving parts are required, production speed can be increased. Instead of the 25 to 35 meters previously common in the industrial sector, more than 100 meters per minute of coated film for battery electrodes can now be produced.

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Solutions for the storage of regenerative energies are of decisive imp ortance in implementing the energy transition. Generation of synthetic natural gas (SNG) from renewable energies enables power storage in the existing natural gas grid and use of SNG without fossil CO2 emissions. Usually, hydrogen is produced by low-temperature electrolysis. This hydrogen is then converted into SNG in a methanation plant.

The EU-funded project HELMETH (Integrated High-Temperature ELectrolysis and METHanation for Effective Power to Gas Conversion) coordinated by KIT has now shown that efficiency in the production of SNG from electric power can be increased by combining both processes. Consistent use of synergies from high-temperature electrolysis and methanation in the HELMETH prototype resulted in efficiencies of power-to-SNG conversion of 76%. This is much higher than the usual 54% of existing power-to-SNG facilities. Larger industrial plants might even reach efficiencies over 80% in case of further optimization.

• Data sheet