North American ECA Critical to LNG Uptake
The introduction of the North American Emissions Control Area (ECA) in August 2012 was a watershed for the uptake of LNG, says James Ashworth of Energy consultancy TRI-ZEN International of Singapore in the company’s latest report: LNG as a Marine Fuel. “LNG as a marine fuel can no longer be described as a Nordic curiosity.”
Ashworth says 2013 saw a surge of intentions, conversions and new building orders for vessels operating in North American ECA waters. “This has brought a minor and welcome resurgence in USA shipbuilding. Europe is also making steady progress and we now expect to see the pattern followed globally.”
The report highlights many LNG-fueled newbuildings and changes in the US container vessel market. TOTE Marine will operate its Florida to Puerto Rico route with new gas fuelled vessels from 2015/6 and its CON-RO, Tacoma to Alaska route with converted vessels. Likewise, Jacksonville, Florida based Crowley has inked contract for two LNG fuelled CON-RO vessels to serve their USA – Puerto Rico routes from 2017. Matson Navigation Companyhas also ordered two 3,600 TEU dual fuel container vessels from Aker Philadelphia for delivery in 2018 for service on its US West Coast – Hawaii routes.
“Over past years we have predicted that LNG would become the preferred choice of marine fuel, replacing oil, even though most existing tonnage is unsuitable for conversion and will have to be replaced. We stand by that prediction. Today, only LNG meets in full, da Vinci’s requirements for true ‘sophistication’ that is, simplicity,” says Ashworth.
In a new development, Wärtsilä has launched the world’s first low-pressure gas injection 2-stroke engine. The problem for 2-stroke cycles and gas fuel has always been that containment of gas at the very high injection pressures required has led to “methane slip”, whereby un-combusted gas passes through the engine from the exhaust system.
“Methane, the main component of LNG, is a virulent greenhouse gas, so the avoidable emission of such volatile organic compounds (VOCs) is desirable at a minimum and may fall subject to future legislation under the IMO,” says Ashworth. “This is an important development, as 2-stroke cycles have traditionally offered higher levels of fuel efficiency than 4- stroke, making them suitable for long voyage vessels.”
In January 2014, Mississippi based Gulf Coast Shipyard announced the launch of the first of six Harvey Gulf International Marine 302’ x 64’ (92m x 20m) dual fuel offshore supply vessels.
Looking to the future, Ashworth sees more technology developments. One of the few disadvantages with LNG is that it takes up more space than diesel to deliver the same energy content. Depending on the gas source you need 1.6 – 1.7 times the volume to go the same distance compared with diesel. Probably the greater advantage is that super cooled LNG substantially reduces the burden of dealing with unwanted boil off gas. A ‘slush gun’ has been developed and tested in a European pilot plant. The LNG slush exits the gun at 91K or -185?C, leaving 22.5?C before the flash point of LNG and the commencement of boil off gas generation.
Another potential role for the LNG slush is in the cooling of electric motors and cables to create electrical ‘super conduction’, thus enabling more efficient power generation. As a general principle, LNG can also be used for a range of cooling processes aboard ship, from cargo chilling to air conditioning system to engine air intake pre-chilling to improve combustion efficiency.
“Though we may not see it immediately, things have moved on a long way for LNG as a marine fuel in the past year. No longer a purely Norwegian and small vessels play. Big ships are, or soon will, be operating on both sides of the Atlantic and burning gas. The latest large cruise ferries burn gas. The fastest ship in the world burns gas.”
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