LNG that the PSVs will be continuously manned with a certified Environmental Officer, be completely built with environmentally friendly materials, and have advanced alarms for fuel tanks and containment systems. Tirelli sees several other types of vessels that could migrate over to LNG power. “The Wärtsilä 34DF engines matches the typical applications covered by its power range. Within those, Platform Supply Vessels and AHTS are for sure natural adopters. In addition to that, medium size Ro-Ro, Ro-Pax or ferries are the other markets where the 34DF engine is establishing itself as the market leader. Wärtsilä has already been awarded an order for 34DF engines and LNGPac supply for a ferry being built for Canadian owner STQ.”
METHANE SLIP Liquefied Natural Gas is composed mostly of methane. One issue for dual-fuel, four-stroke engines has been methane slip, which occurs when methane (CH4) is released in the exhaust because of incomplete combustion in the cylinders. This is problematic when considering that methane is more efficient at trapping radiation than CO2. The U.S. EPA says that pound for pound, the comparative impact of CH4 on climate change is over 20 times greater than CO2 over a 100-year period. EPA says CH4 is the second most prevalent greenhouse gas emitted in the U.S. from human activities. In 2010, CH4 accounted for about 10% of all U.S. greenhouse gas emissions from human activities. Methane is emitted by natural sources such as wetlands, as well as human activities such as leakage from natural gas systems and the raising of livestock. For the most part, the tendency to release methane is highest when engines are operating at lower loads. Engine manufacturers
are of course aware of this challenge, and research is being carried out to minimize methane slip. Achieving maximum reduction of greenhouse gases from gasfuelled vessels will require carefully matching the engines and arrangements for the application and modes of operation. “The EU and the IMO are aiming for very ambitious CO2 reductions in the years to come,” says Tirelli. “Even if shipping is the most energy efficient mode of transportation, we must be prepared to be challenged based on shipping’s own reduction potential. In this setting, LNGfuelled vessels will certainly be one significant part of the solution.” Continues Tirelli, “Wärtsilä is constantly focusing on reducing the environmental impact of its products to a continuously higher level. Since the introduction of gas-burning technology in the marine market, several steps have been done in order to reduce the THC emissions from marine engines. Changes in combustion spaces design, engine parameters, engines tunings, etc, have all been contributing to the current achievements. Wärtsilä Dual-Fuel technology is today able to comply with the most stringent THC regulation in the marine market, set by Norwegian authorities.” One of the biggest hurdles for the advancement of LNGfuelled vessels is bunkering infrastructure and regulation (see LNG: The chicken and the egg problem in this issue). “The LNG market is developing fast and spreading all around the world,” says Tirelli. “Norway has been a pioneer in LNG for marine use adoption, followed by few other countries in the Baltic Sea region and, closely, by Canada and U.S. In North America the market potentials are extremely high and the presence of abundant and price-attractive natural gas supply will definitely play an important role in its fast establishment.” ■
AD 178x126mm HYDREX STRIP_Opmaak 1 27/08/12 11:54 Pagina 1
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22 MARINE LOG May 2013