MAN Cryo supplied liquid hydrogen fuel system for a superyacht
MAN Cryo, the cryogenic equipment division of MAN Energy Solutions, supplied a liquid hydrogen-to-gas-fuel supply system for a superyacht.
PHOTO: Hydrogen-fuelled superyacht called Project 821, designed by Feadship. Man Energy Solutions
The yacht is constructed by Dutch shipbuilder, Feadship. It will be powered by fuel cells that run on hydrogen.
The fuel gas supply system will “store the hydrogen in liquid form, evaporate and heat it” onboard the vessel. It will supply gaseous hydrogen to the fuel cell for propulsion.
The fuel supply system includes a cryogenic liquid hydrogen storage tank with a temperature maintained at -253°C.
“MAN Cryo faced a number of challenges during the project, in great part owing to the lack of existing design codes and standards to follow in order to get approval for its tank design. Normally, type C LNG tanks are designed according to IGF code, but this is not fully applicable to hydrogen,” MAN Cryo said.
“Instead, MAN Cryo approached Lloyds Register with a risk-assessment-based design that is considered safe and approved for placement [of hydrogen fuel tanks] below deck,” it added.
The system will include vent masts to safely release excess hydrogen gas in case of overpressure or other emergency situations. It also includes piping and bunkering stations, MAN Cryo said.
"LH2 [liquid hydrogen] is transported to the storage tank from a truck, bunker terminal, or bunker ship via the bunker station on the ship side. The bunker station is connected to the TCS [tank connection space] on the tank via bunker pipes." TCS comprises equipment that manages LH2 tank and bunkering process.
Challenges with hydrogen as a bunker fuel
Hydrogen-based technologies are making their way into short-sea shipping due to green hydrogen's zero-emission properties. However, some concerns around hydrogen as a mainstream fuel still linger.
“The key challenges for hydrogen as a fuel are managing safety and storage. Hydrogen is both explosive and flammable, so safety concepts for ship system designs must be developed,” classification society Bureau Veritas has explained.
In addition, hydrogen has a volumetric energy density that is 4.6 times lower than VLSFO and the lowest among the currently discussed fossil fuel alternatives, according to classification society American Bureau of Shipping (ABS). This means that to achieve the same energy output, hydrogen requires 4.6 times more volume of fuel compared to VLSFO.
Due to its very low energy density, hydrogen-powered vessels would need much larger tanks to store the same amount of energy as VLSFO- or LNG-powered vessels.
Since hydrogen needs to be compressed or stored cryogenically at low temperatures, it further adds to the complexity of storing hydrogen on board. This could also increase the costs associated with bunkering and operational logistics.
By Konica Bhatt
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