Seaworthy

Converting the approximately 100,000 commercial ships on the world’s oceans to CO₂-neutral propulsion systems is one of the greatest challenges facing climate policy, since a large part of this fleet is operated on the high seas. The range of any new propulsion systems must be able to cover these distances. In merchant shipping, for example, container ships travel the route from Shanghai to Rotterdam without a stopover. Due to the heavy weight of batteries, electricity is not an option as an energy source. If used directly, “green” hydrogen obtained from solar and wind power is also suitable only to a limited extent.

The volumetric energy density of hydrogen – even when liquefied and stored at -253 degrees Centigrade – is seven times lower than that of conventional marine diesel. This would require huge fuel tanks, which in turn would not be practical. It’s thus a good option to chemically bind the regeneratively produced hydrogen. An ideal candidate for this is methanol, a simple alcohol that is liquid under normal conditions and has about three times the energy density of liquefied hydrogen. The technical methods for the production are tried and tested because methanol is already an important basic material in the chemical industry. If the carbon for the methanol production isn’t derived from fossil sources but separated from the air, for example, or if the methanol is generated from biomass, the fuel is completely climate-neutral.

Modular solutions for carbon neutral shipping

Methanol can be used in polymer electrolyte membrane (PEM) fuel cells that operate with an upstream reformer. Through steam reforming, the system produces hydrogen, which reacts with oxygen in the fuel cell to produce the electricity required for the propulsion as well as the on-board power supply. Freudenberg Sealing Technologies has developed such a fuel cell operated with methanol in a container design with a view to its implementation in shipping.