Liquified Natural Gas (LNG), is being considered as an effective alternative to Compressed Natural Gas (CNG). In Trondheim, Norway, buses filled with LNG will soon undergo test trials.

Compared to CNG, LNG contains more energy per unit weight. It is also believed that emissions of nitrogen oxides (NOx) from using LNG will be 20 per cent less than the emissions from modern diesel engines. The organisations involved in the new experiment include Marintek of the Norwegian Foundation for Scientific and Industrial Research, Trondheim Bus Company and Norway's ministry of transport.