From 2013 onwards Energy Efficiency Design Index (EEDI) for new ships has been in force. The EEDI value for a given ship is calculated according to a standard formula and compared against a ship specific standard by means of a so called reference line which will be gradually changing (decreasing) in subse-quent years. The article presents possible ways of increasing ship propulsion efficiency in order to de-crease ship propulsion power, EEDI value and CO2 levels.