that an LNG engine with a WHR system saves money compared to a diesel engine with WHR. There is a higher initial investment cost but it is a cost efficient method and environmentally sound one. Environmental and safety issues Natural gas consists mainly of methane, which has a much stronger greenhouse effect than ref: Global warming potential. Climate impacts of methane are due largely to methane leakage. For example, there is an issue called methane slip. Methane slip is when gas leaks unburned through the engine. Methane has a GWP(20) (20-year global warming potential) which is 86x higher than . If methane slip is not controlled, environmental benefits to using natural gas are reduced and can cancel out the advantages over diesel or bunker fuel due to the high greenhouse effect of the methane. Another challenge is hazards associated with the LNG being stored at very low temperatures. Insulation of the tank is critical, and there's possibilities of structural brittleness and personnel frostbite injuries. Essentially, since it is established that LNG for ship propulsion reduces and other pollutants compared to common heavy fuel oils, LNG implementation depends on these key factors: Gas availability, demand for ships, emission limits (emission controlled areas), LNG tank installation, and safety requirements. Challenges related to the use of LNG should be taken into consideration. Challenges such as the lack of infrastructure in the majority of commercial ports, crew's limited experience running engines with gas fuels, the future price of gas, and the required safety measures all are critical points to be considered. Use of LNG reduces Sulfur Oxides by nearly 100 percent, and it reduces Nitrogen Oxide emission by about 85 percent. There is considerable debate as to whether use of LNG results in reduced greenhouse gas emissions, with studies finding that methane leakage negates climate benefits. The requirements concerning the use of LNG fuel in shipping, in particular technical and safety requirements are set out in International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels, abbreviated as the IGF Code. References Marine engines Liquefied natural gas