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Ship-board Energy Efficiency Measures - Various considerations

Shipboard activities for energy efficiency: All ship staffs have roles to play on ship energy efficiency. However, the role they could play would be different and its effectiveness will vary. For example: The above list does not negate the importance of all ship-board personnel in impacting the ship-board energy efficiency activities. It only highlights those that could have more influence. In fact, all personnel could play their role and without their buy-in the task of ship-board energy management will not be successful. Building up a culture of care for environment and fuel saving between staff is a prerequisite for any successful ship-board energy management.

Importance of communications between departments

One of the issues observed most of the time is the lack of optimal organisational communications between various departments that lead to waste of energy. For example, communication between deck and engine departments is essential for machinery use optimisation. In an effective ship-board energy efficiency programme, the collaboration and communications between all departments need to be enhanced. This may be achieved via consideration of energy efficiency at daily meetings and relevant ship-board work planning for reduction of electricity, compressed air, fresh water, etc. use.

Ship-board Energy Efficiency Measures

It was widely argued and shown that these kinds of measures are not fully under the control of ship staff, thus the issue of communication and coordination between ship, shore office, charterer, shipper, etc. were highlighted. In this module, energy efficiency measures are covered that to a large extend and primarily are in the hand and under control of the ship-board staff (although not all of them by 100%). They could be the subject of ship’s in-passage activities for energy efficiency. An overview of major aspects of ship-board activities that impacts the ship’s fuel consumption coming under this category are briefly introduced first and then fully described in other sections of this module.

Optimized ship handling

Optimum trim: Most ships are designed to carry a designated amount of cargo at a certain speed for certain fuel consumption. The same applies to ballast operations. Whether loaded and unloaded, for such conditions, normally there exists a ship trim that minimises the propulsion power, thus main engines’ fuel consumption. In fact, for any given draft there is one optimum trim that gives minimum ship resistances. In some ships, it is possible to assess optimum trim conditions for fuel efficiency continuously throughout the voyage. Setting the ship trim is to a large extent in the hand of ship-board staff although loading, operational and navigational constraints may limit the full extent of proper use of this energy efficiency measure.
Read more on Energy efficiency measures -Trim optimization.....

Optimum ballast: Ships normally carry ballast water to ensure ship’s stability and safety. Normally, ballast levels should be adjusted taking into account the requirements to meet ship stability, steering aspects of the ship and optimum trim. This does not necessarily mean carrying lots of ballast water all the time. This unnecessarily increases the ship displacement that directly increases fuel consumption. Thus there is an optimum ballast condition that needs to be achieved through good cargo planning as well as voyage planning. Therefore optimising the ballast levels for energy efficiency within the framework of ship stability, safety, steer-ability and optimum trim can be regarded as an energy efficiency measure.
Read more on Energy efficiency measures- Ballast water management ...

Optimum use of rudder and autopilot: There have been large improvements in automated heading and steering control systems technologies. Whilst originally developed to make the bridge team more effective, modern autopilots can achieve much more. An integrated navigation system can achieve significant fuel savings by simply reducing the distance sailed “off track”. The principle is simple; better course control through less frequent and smaller corrections will minimize losses due to rudder resistance. In some cases, retrofitting of a more efficient autopilot to existing ships could be considered.Read more on

Optimised propulsion condition

Hull maintenance: Hull fouling always happens in ships. The rate of hull fouling will depend on a number of factors such as quality of paint, ship service speed, periods of idle /waiting and ship geographical area of operation. Hull resistance can be optimized by new advanced coating systems, possibly in combination with hull cleaning at certain intervals. Regular in-water inspection of the condition of the hull is recommended. Consideration may be given to the possibility of timely full removal and replacement of underwater paint systems to avoid the increased hull roughness caused by repeated spot blasting and repairs over multiple dry dockings. Propeller cleaning: Propeller cleaning and polishing or even appropriate coating may significantly increase fuel efficiency. The need for ships to maintain efficiency through in-water hull and propeller cleaning should be recognized and facilitated by port States.
Read more on Energy efficiency measures- Causes of Hull roughness and preventive measures

Main engine maintenance: Marine diesel engines have a very high thermal efficiency (~50%). This is the best efficiently currently available on the market and is the main reason why diesel engines are unrivalled in shipping. The high efficiency is due to the systematic minimization of heat and mechanical loss of such engines and improved performance parameters that has taken place over many decades.

In particular, the new breed of electronic controlled engines can provide efficiency gains with wider flexibility for example for slow steaming. To keep these engines in optimal condition and performance, they need to continuously undergo on-board condition and performance monitoring. Maintenance in accordance with manufacturers’ instructions in the company’s planned maintenance schedule will also maintain efficiency. The use of engine’s condition monitoring can be a useful tool to maintain high efficiency.Read more on Engine load management ....

Optimised auxiliary machinery

There is a significant number of auxiliary machinery on board ships that use electrical power to function. Such machinery has a number of redundancies for safety and operational purposes so that if one fails, the redundant one could take over and ensure continuous safety and operation of the ship. There aspects to choice of such machinery as well as their operation that impact a ship’s energy efficiency. For example, the way such machinery is used could lead to poor maintenance as well as high energy use. Read more on

Fuel management

Shipping normally uses Heavy Fuel Oil (HFO) that is of lowest quality amongst marine fuels and could be of poor quality, if care is not exercised during procurement and use. Control of quality and quantity of fuels purchased and also on-board fuel treatment can provide significant benefits for safeguarding the machinery from damage but also in terms of energy efficiency.
Read more on Fuel oil management ....

Maintenance and energy efficiency

Ship maintenance operations and management are fundamental for energy efficient operation of its machineries and systems. Deterioration of ship systems’ condition takes place due to normal wear and tear, fouling, mis-adjustments, long periods of operation outside design envelopes, etc. As a consequence equipment downtime, quality problems, energy losses, safety hazards or environmental pollution may result. The end outcome is a negative impact on the operating cost, profitability, customer satisfaction and probable negative environmental impacts. Thus good maintenance is in line with good performance and energy efficiency.

Technical upgrades and retrofits

There are a whole host of technologies that may be used to improve the energy efficiency of an existing ship. Although a decision to choose and install such technology upgrades is outside the hand of ship-board staff, nevertheless this topic will be covered in this module. Typical technologies could include the following.

  1. Optimum propeller and propeller inflow considerations: Selection of the propeller is normally determined at the design and construction stage of a ship but new developments in propeller design have made it possible for retrofitting of later designs to deliver greater fuel efficiency. It is important to know that such changes should be decided by looking at the ship as a whole from hydrodynamic points of view taking consideration for all elements of a ship’s duty cycle. Additionally, improvements to the water inflow to the propeller using arrangements such as fins and/or nozzles could increase propulsive efficiency power and hence reduce fuel consumption.
    Read more on Ships propeller maintenance requirement

  2. Efficient auxiliary machinery and electrical motors: Technology could help in this area via a host of initiatives such as energy saving lamps, energy efficient electrical motors, energy efficiency pumps, etc.

  3. Waste heat recovery: Waste heat recovery is now a commercially available technology for some ships. Waste heat recovery systems use thermal heat losses from the exhaust gas for either electricity generation or additional propulsion with a shaft motor. It may not be possible to retrofit such systems into existing ships. However, they may be a beneficial option for new ships. Waste heat recovery technologies to reduce the need for hot water or steam may be considered for existing ships where such requirement dictates longer operation of the auxiliary boilers.

  4. Boilers and steam system :
  5. In some ship types, boilers and steam are using significant amount of energy for either propulsion turbines or for other auxiliary services such as operation of cargo and ballast pumps, cargo heating, fuel oil treatment and conditions and so on.

Technical Upgrade and Retrofit

One effective way of improving the energy efficiency of a ship is to upgrade ship-board technologies to more energy efficient ones. Upgrading of technologies is not a ship-board activity but nevertheless, the ship-board staff could always engage in proposing such technologies. For this reason, this topic is covered under this module.

A number of technology upgrades can be considered for energy efficiency. It should be noted that applicability of such technologies will depend on ship type, ship size, operation profile and other factors. Thus the decision making for each technology will need to go through the normal process of technical feasibility aspects and economic cost-effectiveness analysis for the specific ship that is under consideration. The technologies described here only shows a good sample, but the list is not comprehensive as there are other potential technologies that may be included.

There are other technologies that may be used for upgrade and retrofit that includes:
  1. Energy saving lamps.
  2. Card controlled or occupancy sensors lighting system for accommodation.
  3. Variable speed drives for pumps, fans and compressors.
  4. HVAC system control upgrade and also pre-cooling of incoming air using outgoing cold air.
  5. Engine de-rating: This is a significant area and only applies for extreme slow steaming.


Energy efficiency measures -Trim optimization

Energy efficiency measures- Ballast water management

Energy efficiency measures- Causes of Hull roughness and preventive measures

Energy efficiency measures- hull roughness reduction

Energy efficiency measures- propeller maintenance

Energy efficiency measures- engine load management

Energy efficiency measures- fuel management

Energy efficiency measures - ship maintenance requirement

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