1) town gas
2) city gas
a gas manufactured for public supply with a Wobbe number range of 23.0-33.5 MJ/m³ (600-785 Btu/ft³)
GRM: n. (1,2)
REG: British English (1), American English (2)
Note: they fall within the first family of gases

ENERGY TERM COURTESY OF ENERGY.EU