The HI-SEA (Hydrogen Initiative for Sustainable Energy Applications) experimental plant, supported by the University of Genoa through the collaboration between the Thermochemical Power Group (TPG) and Fincantieri, continues the studies started within the TESEO project: High-efficiency Technologies for Energy and Environmental Sustainability On-board (PON02_00153_2939517). The system has been specifically designed for the evaluation of fuel cell technology applications in the maritime sector; it is composed of 8 proton exchange membrane fuel cell stacks (PEMFCs), which boast a high energy density and operate at low temperatures, allowing very fast startup and shutdown times, thus making them the most suitable fuel cells applications in the transport sector.

The eight stacks were supplied by Nuvera Fuel Cell, and are located on two branches, electrically in parallel, and within which they are connected in electrical series. The total installed power is approximately 250 kW. Other auxiliary components make up the system, simulating installation in a boat:

• Fuel cell system installed inside a container (8 ft) that is easy to move and place
• Non oil-free industrial air compressor (12 Nm3 / min) with filters, with dynamics different from those necessary for the correct functioning of the fuel cells; it simulates the connection of the cathodic line to the air line present on board
• Two groups of 25 compressed hydrogen cylinders at 200 bar simulating the fuel storage system
• A resistive modular load to make the system perform at different operating profiles
• Two-stage cooling circuit, to simulate heat exchange with a constant temperature source (sea water)

The plant control system is implemented through an HMI interface that acquires (with a frequency of 1 Hz) the status of the stack contactors, the current and cell voltage values ??(minimum, average and maximum) recorded for each stack, data on the temperature of the cooling circuit and the anodic and cathodic flow rates and pressures. A Labview interface has also been developed, that allows to acquire some of the system parameters with a higher frequency (5 Hz). The system’s control allows to promptly detect malfunctions and act on some of the operating parameters.

Starting from 2019, an in-depth experimental campaign was conducted, which led to various results: the compatibility of auxiliaries with the use of fuel cell stacks was studied; a recovery procedure has been developed for stacks when subjected to prolonged periods of inactivity; different stationary and dynamic load profiles are tested to assess the suitability of the system for different operating profiles; some analyses were carried out with Design of Experiment techniques to evaluate the interaction and mutual influence between the operating parameters. It was possible to reproduce the polarization curves of each stack, and to test them in various operating conditions, using static and dynamic load profiles and other load profiles close to those that can be encountered in the naval field. The cells were tested both individually and together (single branch or entire system), to verify their stability even in the presence of the DC / DC converters placed on each branch.

A new experimental campaign on the HI-SEA plant is currently underway. The collected data will be analysed with Response Surface Methodology techniques; data will also be compared with those relating to other PEMFC stacks of similar power (30 kW) tested in the University’s IES (Innovative Energy Systems) Laboratory as part of the MISE TecBIA research project (low impact technologies for the production of energy on ships), of which the TPG is a partner.