Fuel cells for powerful underwater propulsion

_{23.10.2020 I Vera Schmies}

Fuel cells are seen as a great hope when it comes to efficient drive technologies for the future. The innovative fourth-generation fuel cells developed by our experts make submarines more powerful and enable them to remain underwater for longer.

At the beginning of 2020 thyssenkrupp made it into the 100 most active companies in the European Patent Office’s ranking for the fifth time in succession. In 2019 alone the Group filed more than 600 first-time patent applications for inventions worldwide. In its 125-year history thyssenkrupp can look back on more than 22,000 innovations protected by patents.

This innovative strength and the aim of developing tomorrow’s technologies today also drives the experts at thyssenkrupp Marine Systems. Their invention of a fuel cell device with humidifier for use on a submarine is just the first patent from a portfolio which thyssenkrupp Marine Systems has developed over the past six years with a focus on the further development and innovation of propulsion technologies for submarines.

Reinventing a 180-year-old technology

The idea of the fuel cell is already around 180 years old. On the way to the modern drive technology of today, however, the process from 1839 has been constantly developed and new inventions have been patented again and again. Also by the experts at thyssenkrupp Marine Systems. Their new fourth generation fuel cell has been in series production since 2020 and its modular design offers significant advantages for underwater use.

Today, fuel cells are mainly used in areas where the use of classic combustion-based generators is not possible or only possible to a limited extent. For example, for the energy supply in submarines with propulsion systems that are independent of outside air.

As a rule, anhydrous oxygen and hydrogen as educt gases are used to operate such fuel cells. In the fuel cell, the reaction of hydrogen and oxygen produces electricity, which in turn can power a submarine. However, especially when using polymer electrolyte membrane (PEM) fuel cells, it is important that these gases fed into the fuel cell have a high humidity at the operating temperature of the fuel cell in order to ensure the stability of the membrane and thus a long service life of the fuel cell.

A complex cycle for cost-efficient and powerful fuel cell

The task of the invention of a fuel cell device with humidifier, for which thyssenkrupp holds a patent, is to regulate the moisture content of the educts in a simple and reliable way. For this purpose the patent covers a specific arrangement within the fuel cell device. In addition to the fuel cell itself, the patented device consists of a water separator, an educt feed and a humidifier. During the fuel cell process, water and also some oxygen usually remain as “waste products”. Our experts make use of these waste products and return them to the process at a profit. Instead, it is captured and returned to the fuel cell as an educt. The result: In the end, all that is left is water, which is extracted and used again within the humidifier.

For example, our experts use the fuel cell’s own waste heat to keep it sufficiently humid and at the right temperature through a complex cycle, thus increasing the fuel cell’s efficiency. This is a win-win solution, because no additional energy needs to be expended. The heat generated in the fuel cell is efficiently dissipated, because never too much oxygen is and must never be released into the environment. The result is a particularly compact, robust and self-contained system

More safety and longer periods under water

Applied to the application area, this means that the innovative drive technology is used exactly where it is needed in the operational marine business. The new fuel cell is less expensive, offers better performance and allows longer dives – but above all it should have high long-term stability, i.e. not break down in use. The patented device also meets the strict  safety requirements of a submarine. In the event of a fire, the crew cannot escape. Safety on board was therefore a central theme in the development of the innovation.

The thyssenkrupp patent department is one of the oldest in the country. Each year the colleagues protect around 600 new innovations through patents.