Dresden-based Ambartec AG has worked on a storage and transport process for hydrogen in recent years, in which no hydrogen is transported at all, but iron. Iron, which is available in the form of small nuggets, removes oxygen from the water when these two media are brought together, that is, it rusts or oxidizes. What remains is hydrogen that can be used on site. The oxidized iron is then transported back so that the iron nuggets can be reused for the next transport, which works more than 5,000 times. The storage is renewed by reducing the iron oxide with added hydrogen.
Iron nuggets are relatively easy to store in unpressurized vessels. Several of these vessels are then installed in containers so that they can be transported easily and in large quantities. Matthias Rudloff, CEO and one of the co-founders of Ambartec AG, told H2-international: “We’re not limited by the German emissions law nor any accident regulation or the like. We deliver hydrogen to every company - this is not difficult with our storage solution.” His vision is that the iron nuggets in the near future "are only driven back and forth as bulk cargo in intercontinental transport."
Compared to conventional 300-bar pressurized gas storage, this technology offers the advantage of significantly larger storage capacity. A volume of 1,000 liters can release 90 kg of hydrogen. The company recently received funding from the EU and the German state of Sachsen. Together with the technical university TU Bergakademie Freiberg, the storage technology is to be expanded promptly to 800 kg of hydrogen. The preparation of series production is being funded by Sachsen and the EU with funds from the program "FuE-Verbundprojektförderung 2021-2027" (R&D joint project support) with more than 4 million euros. The aim is to build Europe's first H2 storage power station at the Freiberg location by early 2026.
Use as stationary H2 storage power station
The transport of releasable hydrogen in the form of iron nuggets is only one aspect of Ambartec’s technology – it can also serve as stationary H2 storage power stations. It thus offers an alternative to large electricity storage from lithium-ion batteries, the market of which is currently growing. The combination of the storage with a reversible high-temperature solid oxide electrolysis cell (SOEC) should offer a lot of potential. If the power supply is high, the unit can provide SOEC hydrogen, which serves to load the storage. The water required for the SOEC is also obtained during this. When unloading with water vapor, the hydrogen is created, which is then used in the SOFC operation (solid oxide fuel cell) for electricity generation. Although a reversible SOFC is still very expensive today, Ambartec CEO Rudloff is certain that there is a noticeable cost advantage compared to battery storage for larger systems with more than one megawatt-hour power storage capacity.
Rudloff is relying especially on the German power station security law. This requires that long-term energy stores are provided for power plants so that 1 MW is available under full load for at least 72 hours. With the container solution, this is possible at any time, according to the company CEO. "If hopefully the first tenders come this year, we can offer something exciting,” he says.
The Sachsen company is currently targeting the public with their innovative technology, since the storage method is now ready for marketing: “You can already order. From the beginning of next year we can provide hydrogen in containers,” says Rudloff. From 2028, Ambartec plans to sell several hundred of these 20-foot standard containers every year –each of which holds ten vessels with iron nuggets. The CEO also reports: "Purem by Eberspächer is now accompanying us in gaining important findings for the later series production and effectively using the knowledge gained for product optimization – with the aim of producing the final product as low costly as possible."
Ambartec is presenting its hydrogen storage technology at the Hydrogen + Fuel Cells Europe taking place as part of Hannover Messe (see exhibition preview on page 9).
Authors: Sven Geitmann, Jens Peter Meyer
