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Wärtsilä has announced that it has completed the converstion of the product tanker 'Bit Viking' [pictured] to liquefied natural gas (LNG) operation. The vessel was the first to ever undergo a conversion by Wärtsilä from heavy fuel oil to LNG.

Following the completion of the fuel conversion, the Bit Viking was handed over to its customer, Tarbit Shipping in October.

The re-commissioned vessel is operated by Statoil along the Norwegian coastline, and the conversion carried out by Wärtsilä enables it to qualify for lower nitrogen oxide (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. Furthermore, liquefied natural gas (LNG) operation means lower carbon oxide emissions, and virtually no sulphur oxide or particle emissions whatsoever.

First marine dual fuel conversion

The dual fuel conversion of the Bit Viking is the first marine installation in the world to involve converting Wärtsilä 46 engines to Wärtsilä 50DF engines, and the first 50DF marine installation with mechanical propulsion.

"By operating on LNG, the Bit Viking becomes one of the most environmental friendly product tankers in the world," Wärtsilä said.

In August 2010, Wärtsilä announced that it had signed a turnkey project with Tarbit Shipping to convert the Bit Viking to LNG operation. 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 units with related control systems and all adjustments to the ship's systems necessitated by the conversion. The vessel's classification certificate was also updated.

The engines are connected directly to the propeller shafts through a reduction gearbox, thus avoiding the electrical losses that are an unavoidable feature of diesel-electric configurations. This enables a significant improvement in propulsion efficiency, reduced fuel consumption, and corresponding reductions in emissions. It is the first LNG fuelled vessel to be classified by Germanischer Lloyd.

New LNG storage system

The Bit Viking utilizes Wärtsilä's new LNGPac system, which aims to provide the safe and convenient onboard storage of LNG. The two 500-cubic metre LNG storage tanks are mounted on the deck to facilitate bunkering operations and 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 per cent 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 per cent limit on sulphur emissions, the vessel operates on gas.

"Wärtsilä's unique expertise and experience with dual fuel technology, as well as with fuel conversion projects, were the main reasons for us choosing them. We appreciate the technological efficiency of the Wärtsilä solutions and the expert way in which this conversion project has been handled. We are proud that the 'Bit Viking' is now one of the world's most environmentally sustainable tankers in operation," said Anders Hermansson, Technical Manager, Tarbit Shipping.

"This is a major step for Wärtsilä in consolidating its market leading position in LNG solutions for the shipping industry. The successful sea trials with this vessel provide yet further validation of the viability of LNG as the marine fuel of the future. We anticipate that this development will rapidly accelerate during the coming few years," said Sören Karlsson, General Manager, Gas Applications, Ship Power Technology.