Environmental benefits of LNG as a marine fuel reduced by 'slippage'

摘要

The use of liquefied natural gas (LNG) to power vessels has been touted as one of the best means for the maritime industry to meet strict new emissions regulations. The use of LNG as a fuel eliminates 100 percent of sulfur dioxide emissions and particulates and 80 percent of nitrogen oxides. It has been claimed that the use of LNG in engines could reduce greenhouse gas emissions by up to 25 percent, compared with conventional fuels. However, recent research shows that the environmental benefits of LNG fuel may not be as significant as advertised. The incomplete combustion of methane in engine cylinders, known as methane slippage, can decrease, or in some cases, negate the CO2 reduction benefits of using LNG as a mari- time fuel. That is because methane is much more powerful than CO2 as a greenhouse gas. Consequently, release of even small volumes of methane easily spoils potential environmental gains from reduced emissions of CO2.