DLR tests hydrogen drives in the megawatt range
The test field is called BALIS – the same name as the BALIS project launched at the beginning of 2021, a project on fuel cell systems with an output of around 1.5 megawatts for which the DLR Institute of Technical Thermodynamics is responsible. In 2021, DLR laid the foundation stone for the now completed test field on the Empfingen Innovation Campus in the northern Black Forest to develop and test fuel cell drives for various modes of transport. Meanwhile, a follow-up project, BALIS 2.0, is already underway. But more on that later.
In Empfingen, fuel cell systems that are not yet available on the market will be tested with immediate effect, as the researchers emphasise. The modular test field will allow individual components or entire powertrains to be analysed. In addition to the test infrastructure itself, the DLR is also building its own electric drive system in the megawatt performance class – consisting of a fuel cell system, hydrogen tank, electric motor, control components and power electronics.
According to DLR, this makes it one of the first organisations to have such a system. “It consists of a fuel cell assembly, hydrogen tank, electric motor, control components and power electronics and can be used to thoroughly record, understand and qualify all the process steps of a fuel cell propulsion system. The largest commercially available fuel cells for mobile applications have an output of up to several hundred kilowatts. To reach the megawatt range, fuel cell systems need to be constructed from several interconnected modules,” the researchers explain. This results in high operating voltages and currents. These must be optimally controlled for stable and efficient operation. At the same time, a low weight and high efficiency of the drive system are crucial for commercial applications in the heavy-duty sector, they continue.
The initial focus of the work is therefore on the behaviour and optimisation of this megawatt drive system for stable operation under different load scenarios. DLR describes the handling of large quantities of liquid hydrogen (‘LH2’) for the operation of the entire propulsion system as a further research focus of the BALIS test infrastructure. To this end, DLR is currently building a test tank and the necessary refuelling infrastructure with additional funding of around three million euros.
Speaking of procurement funds: the Federal Ministry for Digital and Transport Affairs has subsidised the BALIS test field with 26 million euros. According to DLR, the test environment is already fully utilised for the next three years, for example through research projects or cooperation projects with the DLR spin-off H2FLY, the fuel cell manufacturer PowerCell, the propulsion specialist Compact Dynamics and the gas manufacturer Air Liquide. In the aviation sector, DLR says it is working with companies such as Diehl Aerospace, GE Aerospace and Deutsche Aircraft. The system partner with whom the system was designed and realised is the company AVL.
“The dialogue between research and industry that arises from the construction and use of large-scale facilities like BALIS is invaluable for both sides. This is how we not only jointly demonstrate that new technologies are functional, but also develop them to a size and economic viability that make them an interesting solution for industry,” emphasises Prof. Karsten Lemmer, member of the DLR Executive Board and responsible for innovation, transfer and scientific infrastructures. “In aviation in particular, the step up from a stable propulsion system on the ground to qualification for use in aircraft is very complex and takes time. A facility like BALIS provides the basis and reliability needed to transform aviation.”
Meanwhile, the BALIS project initiated in 2021 as the basis for setting up the test field was given a successor at the beginning of the year with the research and development project. H2FLY is now in charge of BALIS 2.0. DLR and Diehl Aerospace are acting as cooperation partners. The main focus of those involved is to develop and test an aviation-compatible fuel cell module with an output of 350 kW. This basic module will later form the basis for the development of megawatt propulsion systems. According to the initiators, this could be used to power commercial regional aircraft with 40 to 80 seats with zero emissions in the future.
Initial ground tests of the 350 kW fuel cell system are planned for 2025. Alongside the H2FLY home airport in Stuttgart, the aforementioned DLR test site in Empfingen is regarded as the centrepiece of the project. The German Federal Ministry for Digital and Transport Affairs is funding the project with around 9.3 million euros.
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