Although hydrogen filling stations are a rare sight in Germany, the technology is not only ready to use. It is also available. Together with NPROXX, the EDAG Group has developed a high-pressure hydrogen storage system, which it also produces at its Bremen location. It is used in buses for urban public transport and in commercial vehicles.
Large, heavy-duty vehicles such as buses, trucks, or construction machinery often have a load and requirements profile that is very difficult to reconcile with the characteristics of a battery-electric drive (BEV). The desired transition from fossil-fuel drive systems to climate-neutral alternatives can be achieved better with hydrogen on the whole. Both electrification using fuel cells (Fuel Cell Electric Vehicle, FCEV) and conversion of the engine to a hydrogen-powered combustion engine (Hydrogen Internal Combustion Engine, H2 ICE) are feasible alternatives.
Integration of functions as success factor
The key question for many manufacturers is how this kind of system can be accommodated without having to redevelop or extensively redesign the vehicle. The engineers have found a smart answer by integrating various functions to make the most efficient use of the installation space as possible. A key element is the "Tank Systems2Structure" concept, in other words, the frame that includes the hydrogen tanks and essential system components becomes part of the vehicle's support structure, replacing part of the existing construction and so making the body more rigid.
Another example is that the exhaust system for the fuel cell runs through the frame of the tank system. These innovations save both space and weight and simplify the integration of the system with its modular design. The EDAG developers are sure that they have made the most of the available installation space.
The first systems have been delivered to pilot customers and are already in use. The company operates double-decker buses for urban and regional transport, now with fuel cell and hydrogen tanks instead of the previous diesel drive system. The technology developed by EDAG and NPROXX shows here in practice that the solution works – hydrogen drives are therefore no longer science fiction, but an available working technology for today's everyday applications.
Bundled expertise
This fact also had an impact on the EDAG organization. All competencies for existing and new drive technologies were pooled in the newly created "Energy Systems and Drivetrain" business unit. Here, the H2 tank system for the double-decker buses was developed, along with a variant for H2 combustion engines in heavy-duty trucks and construction machinery. The department is also well prepared for other vehicle types or different custom developments.
This requires cross-departmental collaboration between various areas of expertise, ranging from electrical and electronics engineering to software and digitalization, through to complete vehicle development and the organization of in-house production solutions. The project includes both system development and system integration, both on the hardware side, i.e., the tank system with its mechanical components, and on the software side, from the control unit and its programming to data processing, through to end-of-line tests with special diagnostics procedures and stress tests. Furthermore, the EDAG Group is working on initial filling methods such as an automated alternating pressure flushing system or vacuum inertization to protect against uncontrolled ignition or explosion.
Hydrogen requires extreme caution
The safe storage of the highly flammable gas poses a huge challenge. Modern storage systems operate with high pressure so they can take on-board sufficient fuel for longer assignments. The tanks developed and manufactured by NPROXX are available up to a maximum pressure of 700 bar. In the current project, the usual operating pressure is 350 bar. This enables around 40 kg of hydrogen to be stored in the four tanks mounted one above the other. These are certified to EC79 and meet regulatory specifications.
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At the same time, the H2 molecules are tiny, giving rise to an extraordinary amount of work to guarantee that the storage system is leakproof – in all stages of production, for each individual system. This poses particular challenges for the quality of production. The Bremen location, where up to 1,000 of these high-pressure hydrogen storage systems are manufactured annually, has adapted to these stringent requirements, attested by ISO 9001 certification for volume production.
Presentation at the Hydrogen Conference
The high-pressure hydrogen storage system will make its public debut at the Hydrogen Technology Conference & Expo Europe in Bremen from October 19 - 22, 2022. Here EDAG is showcasing its solution on booth 4200. The Hydrogen Technology Conference & Expo will give anyone interested the opportunity to take a look at the system's details and discuss the innovative solutions with the EDAG engineers.
In addition, Marius Koch, Bremen site manager for the Models & Vehicle Solutions business unit at EDAG Engineering will be on hand to answer questions about the hydrogen storage system and EDAG development services. Further information is also available in our whitepaper "Converting a Mercedes Diesel Truck into a CO2-Neutral Vehicle," which describes the use of the high-pressure hydrogen storage system in an H2ICE truck. Download it here!
