Engineering Design In Retrofitting LNG Fuel Tanks for Shipping In Combating Exhaust Emissions

Abstract

Significant pressure is being placed on shipping industry, known to be conservative to new technologies, to reduce engine exhaust emissions. The exhaust emissions from marine engines include SOx, NOx and particulate matters (PM) as well as CO2, a greenhouse gas (GHG) which is increasing steadily due to globalization in trade. This study proposes an engineering design to retrofit a typical bulk carrier with liquefied natural gas (LNG) fuel tanks. The report also evaluates engineering modification with cost reduction and minimum downtime set as ultimate objectives. One key aspect in ship owners’ considerations in capital expenditure is the payback period of an investment. Through the cost analysis, the payback period of a LNG retrofit was estimated at 3.5 years against a MGO fueled ship or 4.5 years against a 0.5% S compliant fueled vessels. This payback period is reasonable and it shows retrofitting vessels with LNG fueled engine as an attractive option. Several other innovative ideas were considered before this concept design was finally selected with a mini-cape size bulk carrier of 5 to 10 years of age used as a case study. As a result of LNG being used as a marine fuel, it will lead to complete removal of SOx and PM emissions. A reduction of NOx emission of up to 85% and a reduction of up to 25% CO2 emission from shipping industry is made possible.