DNV announces the true hybrid OSV

14 Mar 2012
Bjørn-Johan Vartdal: “We know that the hybrid system will reduce energy consumption”

Bjørn-Johan Vartdal: “We know that the hybrid system will reduce energy consumption”

Det Norske Veritas, in conjunction with its partners in the FellowShip project Eidesvik Offshore and Wärtsilä, has announced the next phase of the project, in which the Eidesvik OSV ‘Viking Lady’ will be fitted with a battery pack.

“A true hybrid energy system” is how DNV describes the installation. The class society likens the principle to that of the Toyota Prius hybrid car, but calculations presented by DNV suggest that the environmental benefits for the ship could be considerably greater even than those claimed for the road vehicle.

Viking Lady, which has already demonstrated ‘green’ ship power technology through the use of a gas-diesel electric power system supplemented by a fuel cell, is to be fitted with a battery pack, of about 0.5MWh capacity, as a demonstration of the feasibility of a true hybrid propulsion system.

According to project leader DNV, the primary potential benefits of the hybrid energy system for a ship like the Viking Lady are a 20% to 30% reduction in fuel consumption and CO2 emissions through smoother and more efficient operation of the engines and fuel cell. The reductions of other exhaust components are said to be higher still.

Although the test battery installation is of comparatively small capacity, DNV has calculated the optimum size for a ‘real’ hybrid energy storage battery as around 2MWh. Based on actual fuel costs alone, the return on investment period for the hybrid system with a full-size battery pack is estimated to be less than two years. Other savings, such as reduced maintenance and the potential to benefit from schemes like the Norwegian NOx fund, should reduce the payback time still further.

Bjørn-Johan Vartdal, DNV’s project manager says: “We know that the hybrid system will reduce the energy consumption. When operating, for example, on dynamic positioning, there will be a major fuel saving potential. When in harbour, too, the ship should be able to operate on the fuel cell and its battery power alone, which will reduce emissions significantly. For environmentally sensitive areas, this will be an essential benefit. Additional benefits are related to reductions in machinery maintenance costs and in noise and vibrations.”

A comprehensive measurement program will be carried out on the Viking Lady to verify the saving potential. The project is due for completion in 2013.

As part of this initiative, DNV says that it has developed new class rules for battery-powered ships, claimed to be the first class rules which permit batteries to be used as part of a vessel’s propulsion energy - both as hybrid solutions and for “pure” battery-driven vessels.

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