Impact of Different CNG Compositions on Automotive Applications of Brazilian Market

Over the last few years, a growth of the Brazilian light duty vehicle fleet converted to Natural Gas (NG) has been observed. This is mainly due to license tax reductions on NG vehicles; the increase of the NG distribution around the country and attractive price difference between NG and other fuels. The Brazilian CNG (Compressed Natural Gas) light-duty vehicle fleet has currently reached more than 1,4 million units, being the 2^nd largest in the World. ANP (Brazilian National Petroleum Agency) published in 2002 Resolution n^o104, which defines the NG specification for automotive application. The IBAMA (Brazilian Institute for Environment and Natural Renewable Resources) published in 2002 Resolution n^o 291, which defines ways for the environmental certification of the NG conversion kits. Worldwide, there is little work regarding the impact of NG composition changes on automotive application, due to the difficulty in performing field tests with different NG compositions, vehicles and conversion kit technologies. Some countries, such as the U.S.A. Japan and England, are importing Liquefied Natural Gas (LNG) to supply national demand, compensating for internal production lack or decrease. Depending on the supply origin, LNG compositions can be richer than local specifications, requiring additional discussions related to changes in operational safety, efficiency, performance and emissions for NG areas of application.