Washington Ferries concludes that LNG fuel is safe, clean and cost-effective

25 Nov 2013
Washington State Ferries intends to convert its six Issiquah class ferries to run on LNG, with tanks sited on the top decks

Washington State Ferries intends to convert its six Issiquah class ferries to run on LNG, with tanks sited on the top decks

US ferry operator Washington State Ferries reports that it is a step closer to converting one class of vessels from diesel to LNG operation.

The driving factors behind the move are to significantly reduce fuel costs and emissions. The announcement follows comprehensive studies over the last three years into the economic and safety implications of converting WSF’s six-strong Issaquah class double-ended ferries.

The LNG conversions would involve replacement of the main propulsion engines to use natural gas, and retrofitting of LNG fuel tanks on the top decks. The work would be phased to minimise effects on the service, and it is planned that refuelling would take place at night, out of service, from road tankers, as with the Norwegian LNG-fuelled Fjord1 fleet.

WSF reports that its proposal was officially submitted to the US Coast Guard on 18 November, for formal review by USCG.

The ferries currently operate on ultra-low sulphur diesel fuel, and converting to LNG is expected to result in reductions of 61% in NOx, 59% in SO2, 89% in PM, and 28% in CO2.

“Fuel is WSF’s fastest growing operating expense,” said David Moseley, assistant secretary for the Washington State Department of Transportation, Ferries Division. “Replacing diesel with LNG on the Issaquah class ferries could result in very substantial savings on fuel over the remaining 30 years of their service life. This will also mean a cleaner, more efficient future for our fleet by significantly decreasing emissions.”

WSF’s study process concluded with issuing the final safety and security assessment and a risk-management plan, undertaken in cooperation with DNV. The study found that the LNG proposal is inherently safe with risks as low as reasonably practicable.

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