An analysis was conducted on greenhouse gas emissions from the liquified natural gas (LNG) chain and life cycle of City Gas 13A [caloric value: 46 MJ/Nm(3)(11,000 kcal/Nm(3))], which is produced from LNG. The analysis was based on highly reliable data which are qualified in terms of source and representativeness. Actually, the latest data for CO2 and CH4 emissions from the natural gas field and liquefaction plant were obtained from field studies. Moreover, the analysis includes CO2 emissions during the LNG transportation from exporting countries to Japan, city gas production and distribution stage in Japan and the manufacturing of facilities associated with the production of natural gas overseas to final domestic consumption. The reduction effect of CO2 using LNG cryogenic energy was also considered. The evaluation showed that the level of greenhouse gas emissions and energy consumptions in the modern natural gas production and liquefaction plants were lower than those previously reported due to improvements in the production process. The results of the analysis also provide basic data essential for conducting life cycle analyses in many fields using natural gas. (C) 2001 Elsevier Science Ltd. All rights reserved.