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When MAN Energy Solutions announced that its subsidiary MAN Cryo’s marine fuel-gas system for liquefied hydrogen has obtained in-principle approval by DNV-GL, it pointed to the changes that the global shipping industry is undergoing. For many decades, new technology was rarely if ever adopted or even considered on board ships where the drivers were reliability and robustness, not efficiency, unlike in power and oil and gas industries. On ships, an outage was a strict no-no during voyages.
The slow-speed reciprocating engine capable of burning bunker fuel – a residue of the fractional distillation process with high sulfur content -- was the only technology used for propulsion. A likely technology disruptor was the scaling up of LNG shipping in the 1990s and 2000s where the boil-off natural gas had to be used onboard during voyages. Steam turbines, a technology widely used before the diesels, made a re-appearance on these ships. But, soon enough, the recips came back in the avatar of duel-fuel engines since there wasn’t enough boil-off gas for entire voyages. Moreover, shippers found it far more profitable to reliquefy the boil-off onboard and sell it than use it to propel the ships. For a while, gas turbines were proposed as an alternative on LNG ships since the argument was that if the object was to transport clean-burning natural gas then it made little sense to use bunker fuel. But there was no driver for this solution. Even in the latest LNG ships, a combination of electric motors and reciprocating engines is being used.
But, amidst this resistance, pollution laws were driving the industry to certain technologies. There was a major thrust towards stopping any form of oily, sewage or even ballast water discharge to the sea. Now, air pollution laws limiting sulfur emissions are set to kick-in in the next few years, leading to a general realization in the industry that business as usual will not work. Scrubbers are being developed that could be retrofitted to handle the sulfurous exhaust from the diesels. But, eventually, propulsion systems will be targeted, it appears.
The MAN solution is quite radical and out-in-the-future in shipping. None of the component systems are currently in use and it would take a leap to adopt the MAN system. Electric propulsion is still not in vogue in large ships. Batteries are found onboard only as emergency backup and fuel cells are a far cry from the ocean waves.
Meanwhile, Siemens has bagged a contract to supply batteries for offshore installations, which are stationary applications. Upping the ante, MAN Cryo has developed the Liquid Hydrogen Marine Fuel Gas System design in-house at its headquarters in Gothenburg in close cooperation with the shipowner, Fjord1, and ship designer, Multi Maritime, in Norway.
Dr Uwe Lauber, CEO of MAN Energy Solutions, said: “Winning this approval [from DNV-GL] is a significant development for a number of reasons. As a solution for vessels employed on relatively short maritime routes, such as ferries, this technology is a world-first and showcases our company’s ability to deliver genuinely innovative solutions. Furthermore, Hydrogen is a clean fuel whose profile fits perfectly with the general desire within the industry to move towards cleaner technology. The possibilities for this technology are varied and exciting.”
The system has a scalable design that allows easy adaptation for different shipping types, sizes and conditions. The design is suited for both above- and below-deck applications, offering ship designers the flexibility to optimise their designs in relation to efficiency, and to cargo or passenger space.
Liquefied hydrogen has a temperature of -253° Celsius and is one of the absolutely coldest cryogenic gases there is, which places system components and materials under extreme stresses. Another design challenge was hydrogen’s explosive nature, with the MAN Cryo engineering team accordingly placing top priority on safety.
Once liquefied, hydrogen is reduced to 1/800th of its volume, compared to that of its gas phase, facilitating a more-efficient distribution. As a fuel, hydrogen does not release any CO2 and can play an important role in the transition to a clean, low-carbon, energy system. Liquefied hydrogen can be used to charge batteries for electrical propulsion via fuel-cell technology. MAN Cryo states that it sees a bright future for hydrogen applications globally as part of its target of achieving zero fossil emissions within the marine sector by 2050. In particular, Norway is currently developing several promising hydrogen applications.