Depletion of oil reserves, pollution of air with harmful substances and global warming make it necessary to look for solutions to these global problems. One of the most efficient and comprehensive ways to solve them is to replace petroleum-based fuels for internal combustion engines by alternative fuels. The most promising approach, according to many scientists and experts, is the use of natural gas as fuel both in compressed and liquefied form (Luksho, 2014; Bakhmutov and Karpukhin 2012). The main advantage of natural gas is its better environmental footprint. The exhaust gases of natural gas powered engines contain less harmful substances, compared with petrol and diesel engines. They produce less carbon monoxide by 50-70%, less non-methane organic gases and nitrogen oxides by 70-80% and less carbon dioxide by 15-20% (Luksho et al., 2011; Luksho, 2010). There are certain other advantages of using natural gas as motor fuel. In particular, after desulfurization methane contains almost no sulfur, whose combustion products can be harmful to the health of people and other living organisms, acidify soil and water, destroy the monuments, building facades, etc. Therefore, a comprehensive assessment of the most harmful components of exhaust gases, created by engines running on natural gas, shows that such engines are significantly less dangerous than gasoline or diesel ones. However, transition to gas fuel does not fully solve environmental problems exposed by tightened environmental standards. These problems are mainly related to two components, namely methane and nitrogen oxides, although the transition to advanced (Euro 5 and Euro 6) standards can make it difficult to avoid violating the maximum levels of other regulated substances. In particular, when converting a diesel engine to methane fuel, scientists at NAMI and other researchers reported a very high level of methane emissions, which is several times greater than current standards. Therefore, even Euro-3 required the use of catalytic converters with high content of precious metals, with significantly (three or more times) greater concentration thereof than in the conventional oxidation converters for gasoline and diesel engines.