The International Chamber of Shipping (ICS) says both oil- and gas-fueled ships will not be able to meet one of the major environmental mandates coming to the shipping industry, the need to reduce carbon dioxide emissions.

On top of ballast water and sulphur emissions limits, the International Maritime Organisation set a goal for the shipping industry to cut its total carbon dioxide output by half by 2050.

ICS Deputy Secretary General Simon Bennett says this target can only be met with "zero carbon dioxide fuels.”