Bit Viking’s groundbreaking conversion to LNG

Sustainability assured 2011In October 2011, thanks to a unique, groundbreaking conversion from heavy fuel oil to liquefied natural gas (LNG) operation, the Bit Viking became the first vessel in the world to be equipped with a fully mechanical propulsion system powered by Wärtsilä dual-fuel (DF) engines using gas as the primary fuel.

Back in August 2010, Wärtsilä announced that a turnkey project to convert the Bit Viking to LNG operation had been signed with Tarbit Shipping, a Swedish company that has been transporting bitumen, petroleum products and chemicals since 1962. The scope of the conversion package from Wärtsilä included deck-mounted gas fuel systems, piping, two six-cylinder Wärtsilä 46 engines converted to Wärtsilä 50DF engines with related control systems and all adjustments to the ship’s systems necessitated by the conversion. This enables a significant improvement in propulsion efficiency, reduced fuel consumption, and corresponding reductions in emissions. The Bit Viking is the first LNG-fuelled vessel to be classified by Germanischer Lloyd, and the vessel’s classification certificate was updated as a result of the conversion.

The re-commissioned vessel is operated by Statoil along the Norwegian coastline, and the conversion carried out by Wärtsilä also enables it to qualify for lower NOx emission taxes under the Norwegian NOx fund scheme. The fund is a cooperative effort whereby participating companies may apply for financial support in return for introducing NOx reducing measures.

As well as the NOx-related benefits, LNG operation means lower carbon oxide emissions and virtually no sulphur oxide or particle emissions whatsoever. All in all, equipped with a double-engine installation, propellers, steering gear, rudders and duplicate control systems, the conversion has made the Bit Viking one of the world’s most environmentally-sound product tankers in its class.

“This onboard conversion of marine engines is a world-first,” says Kai Alavillamo, Project Manager, Services, Wärtsilä. “It’s a natural step. We have more than two decades of experience with dual-fuel technology and converting land-based power plant engines from running on heavy fuel oil to run on gas is a well-established procedure world-wide, but no company has carried out this type of work onboard until now.”

The Bit Viking also utilises Wärtsilä’s new LNGPac system, which enables the safe and convenient on-board storage of LNG. Two 500 cubic metre LNG storage tanks are mounted on the deck to facilitate bunkering operations and to permit the bunkering of LNG at a rate of 430 cubic metres per hour. The storage tanks provide the vessel with 12 days of autonomous operation at 80% load, with the option to switch to marine gas oil if an extended range is required. When visiting EU ports, which have a 0.1% limit on sulphur emissions, the vessel operates on gas.

“The final result is a significant improvement in propulsion efficiency, reduced fuel consumption and corresponding reductions in emissions,” says Giulio Tirelli, Marketing and Application Development Manager at Wärtsilä Ship Power. “The Bit Viking engine conversion will open up the market for many additional applications powered by Wärtsilä’s gas-fuelled engines.”

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