Environmental restrictions now favor cleaner fuels, and Natural gas (LNG) is one of the most promising alternative fuels. Highly efficient natural gas fuelled engines have been developed since around 1990. These engines are now entering maritime applications, offering significant emission reductions, both in a local and global perspective. Using LNG as fuel reduce NOx emissions by up to 90%, SOx and particulate matter (soot) are reduced by 95–100% and CO2 emissions are reduced by up to 25%, when compared to traditional marine fuels. These emission reductions are significant contribution especially in local and regional environments. Using LNG as a clean fuel also offers a significant increase in total energy efficiency. Combining power and heat generation, natural gas fuelled engines for on-shore power generation offer a total thermal efficiency of 80–90%, depending on the waste heat recovery rate. For liquid fuels exhaust heat recovery is limited due to the sulfur content, which may cause acid corrosion. Onboard ships, LNG fuelled engines have potential to utilize waste heat to obtain significant higher thermal efficiency than their diesel engine counterpart.
LNG is mainly available from fossil sources, but now also increasingly from renewable sources as bio-gas. For storing and transportation LNG is preferred as less challenging compared to high pressure CNG. On the coast of Norway a LNG distribution system is now being built, supplying a fleet of more than 40 ships. LNG is transported by special designed small LNG carriers from the production plants to a series of main terminals along the coastline. From these main terminals the LNG is distributed by trucks to the local fuelling stations, or for direct fuelling of the ships.
This paper will present the basic technology and experiences from this full scale LNG fuel system. The paper will discuss local and global environmental benefits, technical solutions, safety issues, and costs issues related to the distribution system and the on-board fuel installations.