WEiteR

Hydrogen has been identified by the BMWi as a key element of the energy transition. The use of hydrogen as an energy source is therefore a significant component of the strategy to reduce CO2 emissions in Germany in the coming years. Particularly in the traffic and transport sector, this energy carrier offers the possibility of replacing fossil fuels.
In terms of hydrogen storage, wound carbon-fibre-reinforced pressure vessels (CFRP tanks) have become established, which means that the production of these tanks will increase significantly in the coming years as the hydrogen economy expands. Due to the energy-intensive manufacturing process of carbon fibres, a sustainable strategy for the end-of-use of the hydrogen containers to be produced must already be developed today, as an acceptable CO2 footprint cannot be achieved without suitable recycling or reuse. This is all the more true as global production capacities for carbon fibres are currently insufficient to meet the demand forecast for the coming decades. A suitable waste and recycling strategy is therefore essential for both ecological and economic reasons.
The aim of the WEiteR project is to establish a Freiburg competence centre for the evaluation of CFRP hydrogen tanks during operation and at end-of-use at the Fraunhofer Institutes EMI and IWM together with INATECH at the University of Freiburg. As part of the project, solutions for extending the service life, reuse and high-quality recovery of the carbon fibres used - taking into account the ageing of the materials used - are being developed and made available to industry.
Based on monitoring the tanks, innovative methods for tracking and predicting the material properties during the utilisation period are being developed. Depending on the scenario, this should enable an extension of the utilisation time or qualification for a different application. In addition, an innovative peel process for recovering the carbon fibre tapes without significantly shortening the fibres is being investigated and numerically modelled. The aim is to derive a new numerical method for determining peeling process parameters that can be used for different material combinations with a minimum number of input parameters. This strategy differs greatly from current fibre composite recycling processes, which systematically include a shredding stage and thus lead to downcycling of the material. The peeling process, on the other hand, makes it possible to recover and reprocess the fibres as high-quality, stretched continuous fibres.