The rising demand with the declining domestic production of natural gas in the United States (US) has resulted in the need to expand or build more Liquefied Natural Gas (LNG) terminals. Over the past few decades only certain vaporization technologies were considered and employed based on past “tried and true” operating experience by the regulators. With greater emphasis on energy conservation and environmental impacts, it has become apparent that other approaches to LNG vaporization are needed for future LNG terminals.

Proposals have been put forward with innovative technologies which have been used successfully in other cryogenic industries. Some are completely original. With high emphasis on the environmental impacts associated with the LNG vaporization, the options were reduced, especially for the “tried and true” group of technologies. This opened the field for other alternative technologies. Those with lower emissions and lesser environmental impact began to get more consideration. As the fuel prices climbed, the option for fuel gas fired technologies has become less attractive.

Two approaches that are receiving considerable attention involve use of ambient air as a source of heat. Historically, the least utilized for LNG re-gasification, ambient air vaporizers are steadily rising in the choice of technology options being considered. Significantly reduced emissions and limited environmental impact have brought the use of ambient air into favor with those pursuing new permits. Each of the two ambient air alternatives has limitations which must be carefully considered before employing them, either for onshore or offshore locations. Both are reviewed and compared in this paper.