Energy efficiency involves ever-more integrated planning. Hybrid systems are on the rise, and the search is on for viable sulphur-free alternative fuels.

Expect a growing numbers of vessels designed to offer superior energy efficiency through measures such as improved hydrodynamics, use of lightweight materials, and advanced hybrid power generation systems, with energy storage for optimization of performance and operations. In operations, use of overall power management plans to match demand and production will become increasingly sophisticated.

Learn about alternative fuel options in shipping

By 2025, more ships will be designed to operate with less ballast, with lightweight materials replacing steel in non-structural elements.


From energy efficient designs, lightweight materials, air lubrication and coatings, to advanced control systems and energy management planning.

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Overall ship design determines the size and dimensions of the vessel, the hull configuration, material selection, and, ultimately, the ship performance characteristics under loaded and ballast conditions. These, in turn, impact upon fuel use and associated CO2 emissions.

By 2025, more ships will be designed to operate with less ballast, and with lightweight materials increasingly used as a replacement for steel in non-structural elements. This offers substantial efficiency gains by reducing the area of the hull under water and consequently reducing resistance. Furthermore, there will be greater use of technologies such as air lubrication to reduce frictional resistance of the hull by introducing a thin layer of air between the hull and water, thereby lubricating the hull-water contact area.

Hardened low-resistance hull coatings will also be widely applied to reduce frictional resistance and fouling.

Advanced control systems for operation of ship machinery propulsion systems will improve management of the energy flow. For instance, electronically controlled fuel injection systems enable more responsive fuel injection, better combustion, and optimization of performance at various engine loads. Other ship power systems that will be increasingly automated and optimized include power generators, variable speed pumps, transformers, and waste heat recovery solutions.

The overall goal is to provide an energy management approach that optimally matches demand and production, taking into account voyage plans, hotel needs, energy storage (i.e., batteries), supplementary power generation technologies, such as solar panels, and supplementary propulsion systems, like sails and kites.

By 2025, a large share of new commercial ships will probably include some degree of hybridization.


Recent developments in ship electrification hold significant promise for improved energy management and fuel efficiency.

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Battery powered propulsion systems are already being engineered for smaller ships, while the current focus of engine manufacturers is on hybrid electric solutions for larger vessels.

Significant growth in hybrid electric ships should be expected after 2020 in ship segments like harbour tugs, offshore service vessels, and ferries. By 2025, a large share of new commercial ships will probably include some degree of hybridization. For large, deep-sea vessels, for instance, hybrid architecture may be utilized to power auxiliary systems, and for manoeuvring and port operations. Shifting from AC to DC grids on board will also allow engines to operate at variable speeds such that the engine can operate more efficiently at low loads.

Additional benefits of hybrid-electric ships include power redundancy, noise and vibration reduction, and decreased emissions (NOX, SOX and particulate matter) in ports and populated coastal areas.

The energy density of batteries is a limiting factor that has an impact on the size of batteries and the cruising range of electric ships. New battery chemistries may offer energy density that is one order of magnitude higher than current levels.

With this level of energy density becoming commercially available and affordable, it should be expected that the share of hybrid propulsion systems and electric ships will rise rapidly and gradually become comparable to conventional vessels. However, this is not expected to happen before 2025.


Recent developments in ship electrification hold significant promise for improved energy management and reduced emissions.



Alternative fuels are essentially free of sulphur and thus help with compliance with environmental regulations, as well as the potential for a smaller carbon footprint.

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One key factor that will affect uptake is the price of these fuels. Other questions that need to be addressed are related to local and global availability, production techniques, and safety and reliability concerns. The alternative fuel options available today or in the foreseeable future include:

  • liquefied natural gas (LNG)
  • liquefied petroleum gas (LPG)
  • methanol
  • ethanol
  • biodiesel
  • dimethyl ether (DME)
  • biogas
  • synthetic fuels
  • grid electricity
  • nuclear propulsion, and
  • hydrogen.

New fuels often require new on board systems and machinery, and shifting from one fuel (heavy fuel oil (HFO), marine diesel oil (MDO) to another (e.g., LNG) will take time, and may lead to unforeseen technical issues and delays for pioneers. Thus, a fuel that can be introduced without significant modifications to the machinery and storage facilities has the advantages of simplicity and low capital costs.

LNG was already utilized as a fuel by LNG carriers in the 1960s to take advantage of the fuel available on board in the form of boil-off gas. The first LNG-powered vessel was built in 2000, and at present there are about 75 LNG-powered ships in operation, excluding LNG carriers, and another 80 under construction. In addition, 40 ships have been designed to be ready for LNG retrofit. The growth in LNG-powered ships is expected to accelerate towards 2025. LNG is currently a particularly attractive fuel option for vessels operating in North American waters that have to comply with the Tier III NOX emission standards. The adoption of a 0.5% sulphur limit in European waters in 2020, in addition to the current ECA, could spur accelerated growth of the LNG-fuelled shipping fleet. A number of other sulphur-free fuels can also be used as a substitute for oil in dual-fuel engines. Amongst them, biodiesel, LPG, and methanol are of particular interest because they also offer significant reductions in emissions of NOX and particulate matter (PM).

Fuel availability and pricing will be decisive factors for widespread adoption of any alternative fuels in shipping. The development of bunkering infrastructure is a prerequisite to allow large, ocean-going ships to use alternative fuels. Other factors, such as the high cost of building or retrofitting dual fuel ships, the size of fuel tanks, and concerns about safety, may limit the uptake of such fuels.

A controversial option for powering large vessels is nuclear power. Its main advantages are virtually zero CO2 emissions and a propulsion system suitable for ships that need to be self-supporting for long periods. However, due to significant controversy around nuclear power, and public concerns related to potential consequences from accidents, it seems unlikely that nuclear propulsion will be widely adopted in shipping within the next 10-20 years. The outlook may change if societal acceptance of nuclear power increases and there is stronger policy push to reduce gaseous emissions from shipping.

Comparison of well-to-propeller GHG emissions for alternative fuels

Grams of CO2 equivalent emissions per megajoule

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