LNG Study for Washington State Ferries

  • Client:
    Washington State Ferries (WSF)
  • Completion Date:
    July 2011
  • Project Type:
    Vessel Procurement Consulting
  • Service Categories:
    Naval Architecture
    Marine Engineering
    Marine Consulting
  • Challenge:
    Feasibility study evaluating the conversion of a 144-car ferry to LNG propulsion.


Vessel owners and operators are looking to alternative fuel sources to help them reduce emissions, and the use of liquefied natural gas (LNG) over diesel or gasoline has potential financial and environmental benefits. Glosten studied converting the Washington State Ferries (WSF) 144-car ferry design to LNG propulsion to determine whether switching to natural gas would be feasible and cost effective.

To support the study, Glosten developed a preliminary design for both dual-fuel and single-fuel (LNG only) engines. The operational savings for a single vessel were significant, even with the initial capital cost of the engines. The United States Coast Guard (USCG) reviewed the design and provided extensive feedback, showing their willingness to work with owners during design development while regulatory frameworks around new technologies are still being established.



While there are advantages to using LNG, it is not without its challenges. Converting or replacing machinery and routing piping to make a vessel gas compatible can be costly, considerable space and volume are required for fuel tanks, and LNG supply is still limited in and around ports.

To quantify the costs and benefits of using LNG, Glosten developed a concept design and reviewed the economic, regulatory, and environmental factors associated with implementation. The study concluded that converting the 144-car ferry design to LNG fuel was both technically feasible and cost effective, although some technical and regulatory challenges remain. An independent review by the State of Washington Joint Transportation Committee confirmed that LNG can provide significant savings in fuel costs for Washington ferries and recommended that WSF continue to develop a strategic fleetwide plan with consideration for LNG. Ultimately, WSF’s plans have called for fleetwide electrification over LNG, which better aligned with the state’s decarbonization mandates.

  • WSF 144 Class LNG Tank 10x48 2011-08-15