German submarine specialist thyssenkrupp Marine Systems (TKMS) announced last week that it has completed development and tests of a fourth generation fuel cell (FC4G) system for submarine applications.
The milestone was presented by the company at the quadrennial SubCon submarine conference held in Kiel.
TKMS said the FC4G is designed to be a high-availability modular system composed of redundant components to retain a maximum performance at all times. In terms of H2-storage, the systems rely on metal hydride cylinders much like those of previous generations.
The company noted that these cylinders do not contain any active components; thus, reducing failure to a minimum holding hydrogen molecules safe in place in the crystal lattice of the hydride. Since hydrogen is fed to the system in its purest form, no chemical conversion is required.
In contrast, reformer systems inevitably create CO2 out of a liquid fuel such as diesel oil leaving a trace of CO2 – and potentially other by-products contained in diesel oil such as Sulphur – that must be dissolved into the surrounding sea water by operating electrical pumps.
The same applies to AIP systems based on other principles, such as Stirling engines, closed-cycle diesels, or closed-cycle steam turbines. Not so the FC4G system. The only by-product besides electrical energy is pure water, which is stored on board for weight compensation, according to the company.
“Our customers have been using our fuel cell systems for more than 15 years now. With this 4th generation we are making something great even greater,” Dr. Rolf Wirtz, CEO of thyssenkrupp Marine Systems. “This is the next big step with huge improvements in availability, redundancy, and stealth.”