Engine testing of bus fuelled with LNG

Due to finishing of conventional fossil energy resources, energy security, the desire of independence from imported fuels and reduction of emission of harmful compounds and greenhouse gases in the atmosphere, there is need to explore new technologies using alternative energy sources. One of alternative energy sources, which can be used in transportation, is natural gas. Natural gas can be use in two forms: as a gas (CNG – Compressed Natural Gas), and as a liquid (LNG - Liquefied Natural Gas). Currently the most often used is CNG fuel. The vehicles, which can be supplied by CNG or LNG fuels are called Natural Gas Vehicles (NGV). The article presents the basic properties of liquefied natural gas (LNG) used as a fuel for internal combustion engines. There were made the comparison of the characteristics of CNG, LNG and diesel oil as an engine fuels in different aspects. There was presented the measurement method and measurement equipment applied in the Motor Transport Institute, used to measure the fuel consumption of LNG bus in real traffic conditions in comparison to bus, supplied by diesel oil. The results of measurements in SORT tests were presented and compared with fuel consumption of similar buses fuelled with diesel fuel.