The significant reason for widespread interest in LNG is its potential for making a major contribution to the world's supply of transportable hydrocarbons. For example, if only one-half of the unused, proven gas reserves in some dozen developing countries were to be converted to LNG, they would contribute the equivalent of approximately 8 million barrels per day of crude oil.
Since international, base load LNG projects require unusually large capital investments, the potential of the LNG industry can only be realized if those projects can be financed with borrowed money. But this, in turn, requires a high degree of reliability of each link in the chain which forms the project. Since each individual LNG project has presold its production and arranged its transportation, if one link breaks, it renders the rest of the chain essentially useless-i.e. when the liquefaction plant will not function there is no other place for the idle ships to find a cargo. Similarly, if a ship breaks down, the liquefaction plant must reduce its output since, due to the unique nature of these ships, no alternative ships will normally be available. Thus, transportation of LN G can only be assured through redundancy or interchangeability of ships. But idle redundancy is too expensive, so interchangeability must be sought. A VEDELER (Leif Hoegh & Co., Norway) developed this theme to emphasize the serious need to work toward design standards which, through interchangeability, would create the equivalent of an international pipeline grid for LNG.
R. S. KVAMSDAL (Moss Rosenberg Verft, Norway) began his summary of the Factors Which Influence the Design and Operation of LNG Ships, by discussing the relative importance of shipping costs, in comparison with other elements of the total, landed, cost of transported LNG. When the shipping distance is 10000 nautical miles or more, and the net cost of feed gas is US %0.70/MMBtu, the cost of shipping is higher than all other cost elements together. Thus, the principal factors which influence the design of LNG ships are shipping distance, average number of round trips per year, volume to be shipped, draft or other restrictions, spare capacity requirements, and rules and procedures established by authorities. These factors, and the cost benefits of using large ships, have led most of the existing carriers to be constructed with a cargo capacity of around 125 O00 m3.
While designs have been prepared for capacities of up to 350000 m3, they have not been used because of restrictions of draft and shore installations, considerations of financing and insurance, a trend toward standardization, and the intention to limit the consequences of a breakdown.
While LNG ships have to
