Consequence Analysis of Large-Scale Liquefied Natural Gas Spills on Water

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1.1 Background As public concerns increase over global warming caused by the burning of fossil fuels, natural gas is gaining a lot of attention for the lowest emission of carbon dioxide among the fossil fuels. Thus, governments implementing national or regional plans to reduce greenhouse gas emissions may encourage its use to displace other fossil fuels. According to the Energy Information Administration, the worldwide natural gas consumption in 2030 will increase by about one and a half times as much as in 2006 (EIA, 2009), so that the number and frequency of seaborne transportation of liquefied natural gas (LNG) are expected to increase significantly around the world. In fact, there are a lot of projects to build new receiving terminals in the United States. Also, natural gas consumption is expected to rise rapidly in China and India. With such a growing global demand, recent LNG carriers (LNGCs) become larger up to a 266,000 m3 cargo capacity, which are referred to as Q-Max vessels. Due to the above change in the situation, there has recently been considerable interest concerning possible risks involved in the LNG carrier operations, though seaborne transportation of LNG has been conducted with a very good safety record since 1959. Hence, public authorities have raised their awareness of concern about the possibility of large-scale LNG spill hazards caused by accidental events or intentional attacks. As a result, a number of consequence analyses have been carried out in recent years in order to propose models and approaches or to assess hazards resulting from an unconfined LNG spill over water (Luketa-Hanlin, 2006). However, these studies showed a broad range of results due to their differences in models, approaches and assumptions, since the physics involved in such LNG spills and related phenomena is very complicated. In addition, because of the lack of experimental data for a large-scale LNG spill and subsequent combustion and/or dispersion events, there are many theoretical and experimental gaps related to understanding of the dynamics and limitations in predicting the associated hazards. Therefore, consequence assessment methods based on a combination of theoretical formulations and empirical relationships derived from laboratory and small-scale field experiments are the only practical measure to predict the hazards associated with large-scale LNG spills on water. 23