Energy efficiency and fuel changes to reduce environmental impacts

Book chapter, 2016

Many different emissions from ships are directly related to a ship's fuel consumption. This is particularly true for emissions to air, which are generated during the combustion process in the engines. Hence, improving the conversion process from fuel energy to transport work can be an effective means of reducing ship emissions. Solutions for reducing ship fuel consumption are generally divided into design and operational measures. Design measures primarily include technical solutions implemented when the ship is designed, constructed, and retrofitted, such as weightreduction, hull coatings, air lubrication, improvement of hull design, optimal propulsion systems and harvesting waste energy. Operational measures are related to how the ship or the fleet is operated and include measures such as weather routing, optimal ship scheduling, improved ship logistics, and on-board energy management. Although reducing fuel consumption always generates an environmental benefit, it should be noted that the use of different fuels results in different impacts on the environment for a given energy conversion efficiency. Another way to reduce emissions is therefore related to the type of fuel used on a ship, e.g., diesel fuels, gases, alcohols and solid fuels. However, choosing a fuel is not an easy process because it is influenced by a broad range of criteria, including technical, environmenta l and economic criteria.