H2 Metastore: Development of a hybrid metallic tank system for the storage and use of compressed hydrogen in mobile combustion engines

Storage systems for alternative, hydrogen-based fuels play a central role in the energy transition. The switch to CO₂-neutral energy sources such as hydrogen, methanol, or ammonia will only succeed if storage and refueling are safe, reliable, and have a high energy density.

Hydrogen has a higher energy density per mass than natural gas or diesel and can be stored in tanks and distributed via existing infrastructure. Since gaseous hydrogen takes up around seven times more space than natural gas at ambient pressure, it is stored in liquid form at -256°C or under 350–700 bar in CFRP pressure vessels. However, these are expensive, energy-intensive to manufacture, difficult to recycle, and require complex pre-cooling during refueling due to their low thermal conductivity. In addition, the residual pressure required for fuel cells and combustion systems reduces the usable capacity, which necessitates larger and more expensive tanks.

Emptying the tank almost completely would significantly increase efficiency. The H2-Metastore research project addresses these challenges and is developing a mobile, metallic storage system specifically for heavy commercial vehicles such as airport or port vehicles and construction machinery. These types of vehicles differ significantly from passenger cars and trucks in terms of design, weight, and application profile, and have until now hardly been considered in hydrogen tank development.

The goal is a robust, cost-effective, and fully recyclable hydrogen tank system that causes lower CO₂ emissions during production and enables the almost complete use of the stored hydrogen. In the project, the concept is designed as an example for an aircraft tractor and made transferable to comparable vehicle categories.