Analysis concerning possibilities of reduction of toxic substances and co2 emission by use of dual fuel diesel engines for seagoing ships main propulsion

The goal of the paper is to focus the problem of emission of toxic compounds e.g. NOx, SOx and CO2 from seagoing ships to environment. The VI Amendment to Marpol Convention concerning prevention against air pollution by seagoing ships brought into practice in May 19th 2005 forced ship owners to use means for reduction of environment harmful substances emission to atmosphere. Considerable reduction of these harmful substances can be use dual fuel diesel engines for ship propulsion. Dual fuel engines are fuelled by natural gas having methane as main component. Leading producers of marine diesel engines introduced into production diesel engines DF (Dual Fuel) type. These engines can be fuelled alternatively with natural gas or with heavy fuel oil and marine diesel oil. Today the propulsion by diesel engines fuelled with natural gas is the most popular on ships carrying natural gas cargo i.e. LNG carriers (Liquefied Natural Gas Carriers). Natural gas is freight in liquid form under atmospheric pressure in temperature -163 °C. Due to heat penetration into cargo tanks, the liquefied gas evaporates. Evaporated cargo BOF (Boil Off Gas) is used as a fuel in ship diesel engines. However, dual fuel engines are used on other types of ships not only on LNG carriers. A number of seagoing ships fuelled with natural gas are now under construction. For example container ship 9,000 TEU in Japan shipyard Kawasaki Heavy Industries or container ship 14,000 TEU in Korean shipyard Daewoo Shipbuilding & Marine Engineering for company CMA-CGM. Ships fuelled with natural gas e.g. modern ferries are also built by Stocznia Remontowa Shipbuilding in Poland for Norwegian owner. Adaptation of presently operated ships for fuelling with natural gas is also considered.