Auxiliary systems optimization

Optimizing auxiliary systems to vessel specific operational profiles can lead to significantly reduced energy consumption. Auxiliary systems are often designed to support engines and other primary systems at extreme ambient conditions, or 100% load, which rarely occur. Most of these systems experience supporting primary engines and systems at loads from 80% and down, and with the era of slow steaming, the auxiliary systems typically support engines and systems at loads below 50%, as per Figure 1 which is a representative example.

Operating over a prolonged time at lower loads can induce accelerated wear and can increase the need, cost, energy consumption and complexity of maintenance.

 

Applicability and assumptions

Auxiliary systems optimization is applicable for all vessels with auxiliary systems, regardless of ship type and age. The measure includes full or partial assessment of the energy consumption and production in the vessel auxiliary systems. Through simulation and optimization potential to save energy and fuel can be revealed via

• speed control of pumps and fans
• control strategies of cooling water systems
• replacement of heat exchangers with new more efficient heat exchangers
• adjusted room ventilation, and better control strategies
• redesign of piping and instruments
• smarter utilization of heat recovery from the high-temperature and exhaust gas systems
• smarter sensor and power management systems controlling distribution and consumption of auxiliary energy
• others

Auxiliary systems optimization can represent a wide range of measures, but the key message is that there exist large potentials in saving energy consumed by the vessel’s auxiliary systems. The cost and reduction potential estimate of this measure is highly dependent on whether or not the case is a newbuild or retrofit, the design point(s) distance to actual operating points, complexity in auxiliary system design, etc.

Cost of implementation

The cost of implementation is estimated at $10,000 to $150,000 (USD), spanning from simpler improvement to control of cooling water systems to partial redesign of piping system for cooling and steam, including smart energy automation systems.

Reduction potential

The reduction potential is 1% to 5% of total ship fuel consumption where the reduction potential estimate is highly dependent on whether or not the case is a newbuild or retrofit, the design point(s) distance to actual operating points, complexity in auxiliary system design, etc.

Other References

1. DNV GL Energy efficiency finder / Holistic approach to finding applicable energy efficiency measures to a specific vessel type.

Engine performance optimization (automatic)

A potential lies within ensuring accurate insight to the engine’s condition and performance, enabling both optimizing the engine’s fuel efficiency and verification of the optimization’s effect. With the latest technology and machinery this potential can be realized more or less automatically.

Maintenance, periodic testing and tuning of marine internal combustion engines, for either propulsion or power production, is today an inherent part of the daily work and procedures onboard vessels. Testing is usually done on a monthly basis to ensure correct levels and balance of cylinder pressures, including exhaust temperatures and other parameters. However, these tests are often done with simple tools not calibrated, and performed by crew with limited access to advanced interpretations of the results. As such, test reports are often limited to being reviewed for engine condition via e.g. the exhaust temperature balance only. When changes in engine settings are done based on these tests, the tuning might also not yield the condition and performance sought for due to inaccurate tools, benchmarks and measurements, including unfavourable testing conditions. Also, to ensure achievement of the desired effect from any engine tuning a concurrent re-testing is always recommended, but unfortunately often challenging to make time for.

Applicability and assumptions

Automatic engine performance optimization (auto-tuning) is applicable for all vessels with 2-stroke (main propulsion) engines, irrespective of ages.

Improved balance of the cylinder pressures, and maximum combustion pressures closer to the rated values, is the detailed aim of this measure. The cylinder pressure balance is one important goal to improve the engine condition, enabling more efficient combustion. Peak engine efficiency is another important goal targeted by maximizing the ratio of maximum combustion pressure (P_max) over the compression pressure (P_comp), and subsequently the mean effective pressure (P_mep), within acceptable limits. The level of P_max itself, and the P_max/P_comp and P_max/P_mep ratio, is strongly correlated to the engine efficiency. Increased engine efficiency leads to reduced fuel consumption and a cleaner engine with less carbon deposits in the cylinders and turbocharger, thereby also reducing the maintenance cost. Optimizing an engine to increase efficiency is however usually the opposite of reducing NO_x-emissions, which is important to note as this fact limits any optimization by the applicable NO_x-emission tier level requirements.

Today the task of performance- and condition testing the engine, correcting the results and comparing them to sea-trial, and tuning the engines to optimized P_max/P_comp (efficiency) is done manually. However, electronic auto-tuning is beginning to become standard and the only option for newbuilds. Most large 2-stroke engines being delivered from 2016 onwards have one form of such a system. For 4-stroke this measure is still to become as mature and available. The auto-tuning systems typically measure the cylinder pressures, and adjust the fuel injection timing, balancing and optimizing parameters like P_max and P_comp.

Retrofit of auto-tuning on existing vessels has also recently started to mature and is available for 2-stroke engines with both mechanically and electronically controlled fuel injection pumps and exhaust valves.

Auto-tuning systems also have the added benefit of being an important safety function controlling and avoiding too high cylinder pressure, ignition rise, or P_max/P_comp ratio.

Cost of implementation

The cost of implementation is estimated at $3,000 to $7,000 (USD) per cylinder, depending on newbuild/retrofit and engine type.

Reduction potential

The reduction potential is estimated at 1% to 4% of total ship fuel consumption.

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool
2. Diesel Engines optimization and Fuel savings / Karlsson, Magnus / How to achieve reduction of fuel oil consumption and maintenance cost through carried out optimization of diesel engines / 2013

Engine de-rating

The main engines of almost all existing vessels are both designed and optimized for one specific vessel speed and engine load. The introduction of slow steaming in many ship segments has drastically lowered the actual transit speed from design levels, thus leaving the vessel and its engines operating at none-optimized load levels. De-rating the engine offers the possibility to lower the vessel’s maximum speed, specified maximum continuous rating (MCR), and thereby optimize actual load point with design load point. This results in higher efficiency with reduced specific fuel oil consumption (SFOC) at the new optimum design point.

Applicability and assumptions

This measure is suitable for all ship types and ages where a top speed reduction of 10% to 15% can be expected, and the principle of de-rating an engine for vessels is equally important for when in operation as for choosing the engine type and propeller design for new ships.

De-rating of the main engine, be it permanent or temporary, can be done by different methods varying in cost, flexibility and effort needed. The measure is especially relevant in today’s slow-steaming markets. However, many ship owners are hesitant to reduce the vessels’ top speed. Flexible and reversible de-ratings already exist and can be very attractive, keeping the option easy, and with low cost, speed up again if the market changes. Measures to achieve this include, but are not limited to:

• installing shims between the crosshead and piston rod to reduce stroke length
• cutting out one or several turbochargers, either with permanent or flexible flanges
• cutting out/deactivating cylinders
• various tuning methods/settings of the engine, incl. slow steaming kits (also for retrofit)

The main principle behind the fuel saving benefits from de-rating an engine is derived from maximizing the engine’s maximum cylinder pressure (Pmax) ratio to their cylinders’ mean effective pressure (MEP). A de-rated engine can also be further tuned to optimize the efficiency at the lower operating points. This may be complemented by reduction in cooling capacity of auxiliary systems, or by installing variable frequency drives on pumps, etc.

De-rating an engine will have an impact on the turbochargers and the engine’s NOx-emissions, and requires an evaluation by engine makers and regulatory bodies. New torsional vibration assessments are also typically needed for engine de-rating studies. Some de-rating measures, especially for mechanically controlled engines, may require additional NOx reduction measures that increase the SFOC.

De-rating the engine also opens up for a beneficial propeller exchange, as optimizing the propeller characteristics for better performance at lower engine speeds can shorten the payback time of the de-rating. This however typically also increases the project’s capital investment substantially.

It is possible to achieve a reduced RPM with the same power output for certain load ranges when de-rating, enabling a larger and slower propeller, which typically increases the propulsion efficiency.

De-rating is usually performed during docking and is expected to take approx. 7 to 10 days in dock, dependent on de-rating option. Main challenges are machining of liner and delivery of necessary equipment in time for docking.

Before de-rating it is normal that either makers or other consultancy firms perform engine specific studies to evaluate the potential for de-rating, and the most optimal point, including new turbocharger matching, torsional vibration calculation, and a new propeller design performance evaluation.

Cost of implementation

The cost of implementation is $60,000 to $3,000,000 (USD), dependent on starting point and method and extent of de-rating.

For reference, turbocharger cut out with permanent blinds represents the lower end of the cost implementation scale, while de-rating via more complex and universal measures is estimated at around $1,000,000 (USD) for 5 to 7 cylinder engines. For the largest engines around $2,000,000 (USD) is estimated, and taking into account fitting of a new propeller the high end of the cost scale is reached, i.e. $3,000,000 (USD).

Reduction potential

The reduction potential is estimated at 2% to 10% of main engine total fuel consumption.

Whichever de-rating method is most cost-beneficial typically depends on the vessel’s current operational speed compared to optimum design speed and the engine type/size.

Other References

1. MAN PrimeServ / MAN PrimeServ product brochure on engine de-rating
2. DNV GL Energy efficiency finder / Holistic approach to finding applicable energy efficiency measures to a specific vessel type
3. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Engine performance optimization (manual)

A potential lies within ensuring accurate insight to the engine’s condition and performance, enabling both optimizing the engine’s fuel efficiency and verification of the optimization’s effect. For the majority of existing vessels this potential is only possible to realize manually, unless costly retrofits are made.

Maintenance, periodic testing and tuning of marine internal combustion engines, for either propulsion or power production, is today an inherent part of the daily work and procedures onboard vessels. Testing is usually done on a monthly basis to ensure correct levels and balance of cylinder pressures, including exhaust temperatures and other parameters. However, these tests are often done with simple tools not calibrated, and performed by crew with limited access to advanced interpretations of the results. As such, test reports are often limited to being reviewed for engine condition via e.g. the exhaust temperature balance only. When changes in engine settings are done based on these tests, the tuning might also not yield the condition and performance sought for due to inaccurate tools, benchmarks and measurements, including unfavourable testing conditions. Also, to ensure achievement of the desired effect from any engine tuning a concurrent re-testing is always recommended, but unfortunately often challenging to make time for.

Applicability and assumptions

It is assumed that most ship and engine types and ages have an improvement potential in optimization of engine efficiency, except for a few “best in class” players including occasional special cases. Also, both 2- and 4-stroke engines, mechanic and electronic, are eligible for optimization, and the principles do not change much with use of different fuels either.

Improved balance of the cylinder pressures, and maximum combustion pressures closer to the rated values, is the detailed aim of this measure. The cylinder pressure balance is one important goal to improve the engine condition, enabling more efficient combustion. Peak engine efficiency is another important goal targeted by maximizing the ratio of maximum combustion pressure (P_max) over the compression pressure (P_comp), and subsequently the mean effective pressure (P_mep), within acceptable limits. The level of P_max itself, and the P_max/P_comp and P_max/P_mep ratio, is strongly correlated to the engine efficiency. Increased engine efficiency leads to reduced fuel consumption and a cleaner engine with less carbon deposits in the cylinders and turbocharger, thereby also reducing the maintenance cost. Optimizing an engine to increase efficiency is however usually the opposite of reducing NO_x-emissions, which is important to note as this fact limits any optimization by the applicable NO_x-emission tier level requirements.

The potential for reduced fuel consumption in this measure is twofold, where the first part is testing the engine’s condition and

performance with accurate tools and methods, under comparable conditions with sea trial performance data. The second part relates to actually acting on the potential for improvement identified, and verifying the results through re-testing.

 

 

Regarding the tool to be used for measurement of cylinder pressures, the minimum required quality is advised to be an electronic combustion analyser. The analyser should provide the reader with a full overview of the combustion cycle and the pressure development presented in both absolute numbers and graphs, with possibility to zoom in/out and compare multiple cylinders. See Figure 1 and Figure 2 for examples.

Cost of implementation

The cost of implementation is estimated at $5,000 to $10,000 (USD).

Variable cost will come in addition to the cost of the measurement tool relating to education/training, establishing the methodology and needed procedures, carrying out the job itself, establishing software analysis and trending tools.

Reduction potential

The estimated reduction potential is 1% to 4% of total ship fuel consumption.

The changes in engine settings to optimize an engine with regards to efficiency differs from case to case and engine type to engine type, but one of the most typical changes is setting of the fuel injection timing. In terms of absolute fuel consumption reduction it is evident that the larger 2-stroke propulsion engines possess the largest absolute fuel reduction potential.

Other References

1. Diesel Engines optimization and Fuel savings / Karlsson, Magnus / How to achieve reduction of fuel oil consumption and maintenance cost through carried out optimization of diesel engines / 2013

Exhaust gas boilers on auxiliary engines

Exhaust gas boilers recover the heat from the exhaust gas of auxiliary diesel engines to generate steam and/or hot water, or useful heat for process heating. Depending on system design, these boilers can enhance the efficiency of the auxiliary engine system by up to 20%, leading to lower overall process costs. See Figure 1.

Applicability and assumptions

Applicable for ship types of all ages not fitted with shaft generator where an auxiliary engine will be in service in all operational modes (seagoing and in port). Excessive heat from the engine exhaust could then be recovered and utilized.

In case of ship fitted with shaft generator, the auxiliary engines will normally be in service in port. Excessive heat is then assumed only to be available when in port.

For reference an assumption is made that the auxiliary engines of large deep sea cargo ships in transit usually are run with one 1MW engine at 60% to 80% load, the average power output is around 600 to 650 kW. This can yield an estimated steam production between 450 kg/h and 500 kg/h at 7 barG.

The benefit from the measure might relate to reduced fuel consumption on the auxiliary engine itself due to lower need for auxiliary power for e.g. process heating, where both steam and electricity can be used for heating purposes. Alternatively, and likely more frequent, the benefit may come as reduced fuel oil consumption on an oil fired boiler in cases of insufficient steam production from main engine exhaust gas economizer. To simplify the benefit, the savings are estimated as total percentage saving of the auxiliary engine’s fuel oil consumption.

Cost of implementation

The cost of implementation is estimated at $50,000 to $75,000 (USD) based on size of auxiliary exhaust gas boiler.

Reduction potential

The estimated reduction potential is 0% to 5% of the auxiliary engine’s fuel consumption.

The reduction potential has been estimated to up to 5% for steam production on ships that have oil fired boilers installed, of all ages. The reduction potential is estimated to be up to 1% on ships without an oil fired boiler installed.

Other References

1. Alfa Laval / Efficiency in boilers and beyond
2. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Hybridization (plug-in or conventional)

On a full-electric ship, all the power, for both propulsion and auxiliaries, comes from batteries. A plug-in hybrid ship, similar to a plug-in hybrid car (PHEV), is able to charge its batteries using shore power and has a conventional engine in addition. The ship can operate on batteries alone on specific parts of the route, when manoeuvring in port, during stand-by operations. A conventional hybrid ship uses batteries to increase its engine performance and does not use shore power to charge its batteries.

 

The introduction of batteries enables selection of smaller engine sizes that can operate at optimal loads for a larger portion of the time, due to additional power being obtained from the batteries when required (peak loads). When power requirements are low, the batteries can be charged using the excess energy generated by running the engine still at the optimal load. Also, for vessels with electric cranes and other cargo equipment with transient peak loads and options for regenerating power, batteries can introduce significant benefits. Alternatively, in operating conditions requiring very low loads, the ship may be able to operate on battery power alone saving engine running hours, fuel- and maintenance cost.

Applicability and assumptions

Hybridization is expected to have a wide range of applications, but is likely to be particularly relevant to ferries, offshore vessels and tugs. In addition, hybrid solutions are in general suitable where there are large fluctuations in power output, where the battery bank can stand for power spikes so that engines are constantly operating smoothly within optimal range. Hybridization with batteries can be used on ships with both diesel, LNG and biofuels. Hybridization requires by itself no charging infrastructure on land.

The specific fuel oil consumption of, and emissions from, an internal combustion engine depend on the engine load. Typically, engines are calibrated for optimum performance at high loads. For ship types that experience large load variations during operation, the introduction of batteries may allow the engines to operate optimally with respect to fuel oil consumption and/or emissions. An example of this is dynamic positioning (DP) vessels often experiencing high transient power demands while operating frequently at unfavourable low engine loads.

For the cases when operation solely on battery power is feasible, e.g. for the initially very low engine load operations, maintenance costs can be reduced by avoiding incomplete fuel combustion. Incomplete fuel combustion can lead to contamination of the lubrication oil and the build-up of carbon residue on vital engine parts, inflicting amongst others increased maintenance cost and fuel consumption.

Hybridization of a vessel is favourable also for use in conjunction with direct current (DC) grid system on board. A DC grid system can amongst others disable restrictions for speed on power producing engines, enable these engines to be more optimum at energy storage and production for hybrid vessels resulting in overall fuel savings.

Cost of implementation

A conventional hybrid ship will have an additional cost in the range of $600,000 to $2,000,000 (USD) where the cost increases with the engine and vessel size.

For the plug-in hybrid ship the estimated additional cost of implementation is from $1,800,000 to $3,000,000 (USD).

For a full-electric ship the cost of implementation is in the range of $4,800,000 to $6,000,000 (USD). Again, the costs will increase with engine size and are dependent on vessel type, size and operational profile.

Reduction potential

The reduction potential is estimated at 15% to 30% of total ship fuel consumption depending on vessel operational profile, power production and consumption profile, engine specifics, rules and regulations, etc.

Other References

1. ABB / Example of fully battery powered ferry

Improved auxiliary engine load

Improved engine load in this measure relates to the engine load of the auxiliary power producing engines which provide electrical power to the ship.

The auxiliary engines are used for electrical power production on board and can represent up to 15% of the total fuel consumption for a vessel with diesel mechanical. There are many different engine configurations, with normally 2 or 3 auxiliary engines on a diesel-mechanical vessel, and 4 to 6 auxiliary engines on diesel-electric vessels. The engine performance and efficiency aspects of the auxiliaries are quite similar to the large 2-stroke propulsion engines as they are often more efficient at higher loads.

Applicability and assumptions

Applicable for all vessels at all ages.

The key of this measure relates to the fact that many vessels run more auxiliary engines simultaneously than are actually needed regarding power consumption vs. production-basis during normal deep sea transit. This is amongst others related to risk aversion of black-out, i.e. your only running auxiliary engine dropping out. The safety margin against black-out from running more than one engine can, however, often be reasoned. During manoeuvring or other similar operations losing power production can be very critical, but during deep sea transit in calm weather it is typically not critical to experience a black-out. In addition to risk aversion for black-out, general wear and tear of the auxiliary does tend to bring down their rating (maximum kW production), meaning that the assumed load level is in fact higher. This is quite normal and should easily be fixed via e.g. overhaul of the turbochargers.

In order to minimize the fuel consumption on the auxiliaries through increasing the average engine load, the number of auxiliary engines running must be minimized at all times. This could be included in a ship specific auxiliary engine operation guideline. A guide for the number of engines running could be developed based on the possibility to measure the kWh produced and compared with the operational mode. Lowering the number of auxiliary engines also reduces the engine hours, the rate of wear and tear per hour, lubrication oil consumption and consequently work needed to do maintenance. The average engine load is as such on its own a good performance indicator to work from, but it must not contribute to compromising safety, and a risk based approach is as such advised.

Cost of implementation

There are no direct costs related to improved engine load. However, there might be costs related to training of crew to improve the performance, production of guidelines or software tools to track the performance of this as a measure.

Reduction potential

The reduction potential is estimated at 0% to 20% on fuel consumption on auxiliary engine.

The basis for saving fuel on increasing the load of the auxiliary engines through minimizing the numbers in operation simultaneously can be seen by the example in Figure 1. In the example it is evident that it should be possible to reduce the specific consumption by 5 to 15 g/kWh for over 50% of the auxiliaries’ operational time, i.e. 2.5% to 7% reduction.

Other References

1. Kongsberg Vessel performance optimizer / Paper on cost efficient vessel operation

Shaft generator

As a complement to auxiliary engines, the auxiliary power can be generated by a shaft generator on the main engine.

Applicability and assumptions

Shaft generator is applicable for vessels with diesel mechanic propulsion, for all ages.

Smaller 4-stroke auxiliary engines compared to larger 2-stroke main engines are generally less efficient, having a higher fuel consumption resulting in more expensive operations and higher emissions. There are many different types and configurations of auxiliary- and main engines on vessels, but the vast majority sail with large 2-stroke engines in combination with smaller auxiliaries. Installing a shaft generator on this more efficient engine can be done directly to the main propulsion shaft, or with a gear box to the main shaft. As a redundancy or booster for the main engine there are also shaft generators that can be used as an electric motor driven by auxiliary engine power.

The latest shaft generator configurations can be used independently of shaft speed and maintain a stable voltage and frequency output; this makes it possible to optimize each route with parallel auxiliary operation. Use of shaft generators can reduce the maintenance costs and lubrication costs for the auxiliary engines. The number of auxiliary engines or the size of the auxiliary engines can also be reduced. Using shaft generators rather than auxiliary engine for electric power generation typically also reduces noise and vibration levels.

Installing a shaft generator on the typical main engine is by itself more efficient than producing the same power via a smaller and less efficient auxiliary, but for many cases the shaft generator would in addition increase the total load of the main engine closer to the optimum load point with minimum specific fuel oil consumption.

Shaft generator is an option for many types of vessels, especially those in need of a larger amount of power for heating or cooling, and sailing long transits.

Additional measures advised include new torsional vibration calculations.

Cost of implementation

A typical shaft generator will cost around $400 (USD) per kW. Depending on the required power output and vessel type it is estimated that the cost of implementation will be in the range of $240,000 to $600,000 (USD).

Reduction potential

The reduction potential is 2% to 5% of total ship fuel consumption.

Other References

1. MAN Diesel & Turbo / Shaft Generators for Low Speed Main Engines
2. Wärtsilä Technical Journal / Shaft Generators: propelling vessels toward leaner, greener power generation

Shore power

When a ship docks, it no longer needs energy for propulsion. However, ships may still be large consumers of energy when stationary as several of the ship functions are still operating. This includes ventilation/heating/cooling, pumps, control systems and cargo handling systems. Consequently, the generators are running when in port, resulting in local noise and air emissions as well as global climate driving emission. Rather than letting the generators on board make the electricity this can come from shore power.

Applicability and assumptions

Shore power can be installed for all types of vessel and for all ages with need for power in harbour, and has been used for years especially for smaller vessels, but also some larger passenger vessels.

For smaller vessels to draw power from the land based mains supply when docked is not a new phenomenon. Shore power has been used extensively for many years for vessels with moderate power requirements; typically less than 50 to 100 kW. These vessels are capable of making use of normal grid voltage and frequency, and replace the energy from the generators with the shore power with only marginal investments.

For the larger vessels with higher power requirements (100 kW up to 10 to 15 MW) it gets a bit more complicated. To serve these vessels with shore power, dedicated and relatively costly installations are required, both on land and on board the vessels. This may include upgrading the grid capacity, frequency converters and complex high power connectors. Consequently, relatively few vessels and ports are capable of making use of shore power, even though the environmental upsides are considerable. Still, cold ironing may be regarded as a mature technology that has been in regular use since the 1980s.

Shore power may potentially eliminate the local noise and air pollution related to ship activity in a port. Depending on the energy source, it may also contribute positively to the climate driving effects of ship operation, but as an isolated initiative, it is generally not considered to be among the most cost effective climate initiatives.

On the land side, the high power cold ironing system consists of the following:

• High voltage grid to the port
• Frequency and voltage convertors/transformers
• Control panels and connection boxes
• Cable reel and connectorsOn the ship side the following will have to be installed:
• The grid power solution and the frequency converters typically represent the costliest elements on the shore side. Depending on the availability of grid power and the power requirements, the cost of installing shore power on the shore side will vary considerably.

• Transformer
• Power distribution system
• Control panel
• Frequency converter (optional for greater flexibility)
• Connectors and cable reel (optional for greater flexibility)

Table 1 – Typical system specs for the different power requirements

Power Capacity	Typical spec
<100kW	230/400/440V – 50/60hz
100 – 500kW	400/440/690V – 50/60hz
500-1000kW	690V/6.6/11kV – 50/60hz
>1MW	6.6/11kV – 50/60hz

 

Table 2 – Typical system requirements for different ship types and sizes

Vessel types	<= 999	1000 – 4999 GT	5000 – 9999 GT	10000 – 24999 GT	25000 – 49999 GT	50000 – 99999 GT	>= 100000 GT
Oil tankers	230/400/440V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz
Chemical/product tankers	400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz
Gas tankers	400/440/690V – 50/60hz	400/440/690V – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz
Bulk carriers	230/400/440V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz
General cargo	230/400/440V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz
Containers vessels		400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz
Ro Ro vessels	230/400/440V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz	6.6/11kV – 50/60hz
Reefers	230/400/440V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz
Passengers vessels	230/400/440V – 50/60hz	400/440/690V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz
Offshore supply vessel	230/400/440V – 50/60hz	400/440/690V – 50/60hz	6.6/11kV – 50/60hz
Other offshore service vessels	230/400/440V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz	690V/6.6/11kVV – 50/60hz
Other activities	230/400/440V – 50/60hz	400/440/690V – 50/60hz	690V/6.6/11kVV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz	6.6/11kV – 50/60hz
Fishing vessels	230/400/440V – 50/60hz	400/440/690V – 50/60hz	6.6/11kV – 50/60hz

 

Cost of implementation

Table 3 – Estimated cost for implementing shore power on board vessels

Investment cost for vessel (USD)	1000 – 4999 GT	5000 – 9999 GT	10000 – 24999 GT	25000 – 49999 GT	50000 – 99999 GT	>= 100000 GT
Crude tankers	$50 000 – $350 000	$100 000 – $400 000	$100 000 – $400 000	$100 000 – $400 000	$300 000 – $750 000	$300 000 –$750 000
Chemical / product tankers	$50 000 – $350 000	$100 000 – $400 000	$300 000 – $750 000	$300 000 – $750 000
Gas tankers	$50 000 – $350 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 –$750 000
Bulk carriers	$50 000 – $350 000	$50 000 – $350 000	0,5 – 3 Mill	0,5 – 3 Mill	$100 000 – $400 000
General cargo	$50 000 – $350 000	$50 000 – $350 000	0,5 – 3 Mill	$100 000 – $400 000
Container vessels	$50 000 – $350 000	$50 000 – $350 000	$100 000 – $400 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 –$750 000
Ro Ro vessels	$50 000 – $350 000	$50 000 – $350 000	$100 000 – $400 000	$100 000 – $400 000	$300 000 – $750 000
Reefer	$50 000 – $350 000	$50 000 – $350 000	$100 000 – $400 000
Passenger ship	$50 000 – $350 000	$50 000 – $350 000	$100 000 – $400 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 –$750 000
Offshore supply ship	$50 000 – $350 000	$100 000 – $400 000
Other offshore service ships	$50 000 – $ 350 000	$100 000 – $400 000	$100 000 – $400 000	$100 000 – $400 000	$100 000 – $400 000	$100 000 – $400 000
Other activities	$50 000 – $ 350 000	$100 000 – $400 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 – $750 000	$300 000 –$750 000
Fishing vessels	$50 000 – $ 350 000	$100 000 – $400 000

 

The cost of adapting a vessel for shore connection depends on the plant design and the possibility of varying the voltage and frequency range when needed. Further, it is important to consider that these costs are only for the vessel, not for the implementation at the port side.

Reduction potential

The reduction potential is 50% to 100% in port for the electrical motors on board.

Other References

1. Onshore Power Supply / Independent non-profit website established by the World Ports Climate Initiative (WPCI)
2. Commission Recommendation / EU library of documents related to ports and emissions
3. ISO – Electrical installations in ships / The ISO is a non-governmental organization that forms a bridge between the public and the private sectors. The ISO in co-operation with the IEC and IEEE is currently preparing a standard for High Voltage Shore Connection systems.

Steam plant operation improvement

Experience has shown that there is an improvement potential for boiler operation in terms of general use and maintenance of the boiler and steam plant system.

Applicability and assumptions

This measure is most valid for crude and product tankers, of all ages, as they are the ship types most frequently equipped with large oil fired boilers, where cargo handling and discharge can be vast steam consuming operations. In these cases the condenser performance (sub cooling) and hot well temperatures are of higher relevance. The measure is assumed to be implemented to a greater extent on the larger ships and, therefore, the potential is assumed greater for smaller ships.

The measure involves updating the related procedures, installing/using some new sensor equipment, minor retrofits like new insulation for steam piping on deck, training of crew and some additional maintenance to minimize steam consumption and leakages, and optimize efficiency of steam production. Such updates can relate to areas like tank cleaning, general monitoring and reduction of the steam consumption and leakages, monitoring and tuning of the boiler performance, optimal cargo heating, etc. For boiler performance several aspects are important, but especially control and adjustment of excess air on boiler, feed water temperature, drum pressure, and ambient air temperature and humidity. For steam leakages regular maintenance on disc type steam traps based on performance monitoring is usually advised.

Cost of implementation

The cost of this measure’s initiatives has been estimated at $20,000 (USD) per ship per annum.

Reduction potential

The reduction potential for boiler consumption has been estimated in the range of 10% to 30% of the total boiler fuel oil consumption, with larger reductions per percentage on smaller ships than on larger ships. The reduction potential is also assessed to be the same for new builds as for ships already in operation as this is an operational measure, and it is assumed that new vessels will have the same operational pattern as the existing ships.

The benefit from the measure will come in terms of reduced fuel consumption due to less steam needed on board in addition to more effective production of steam.

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool
2. Third IMO GHG Study 2014 / International Maritime Organization (IMO) / Smith, T.W.P.; Jalkanen, J.P.; Anderson, B.A.; Corbett, J.J.; Faber, J.; Hanayama, S.; O'Keeffe, E.; Parker, S.; Johansson, L.; Aldous, L.; Raucci, C.; Traut, M.; Ettinger, S.; Nelissen, D.; Lee, D.S.; Ng, S.; Agrawal, A.; Winebrake, J.J.; Hoen, M.; Chesworth, S.; Pandey, A. / 2014

Waste heat recovery systems

Waste heat recovery systems recover the thermal energy from the exhaust gas and convert it into electrical energy, while the residual heat can further be used for ship services (such as hot water and steam). The system can consist of an exhaust gas boiler (or combined with oil fired boiler), a power turbine and/or a steam turbine with alternator. Redesigning the ship layout can efficiently accommodate the boilers on the ship to better fit these systems.

Waste heat recovery is well proven onboard ships, but the potential can be variable depending on the size, numbers, usage and efficiency of the engines on board. Furthermore, these measures are usually not relevant for retrofitting, due to large costs and efforts related to redesign, steel work, extra weight, etc.

Applicability and assumptions

This technology can be applied to all ships regardless of size, age and type even though it seems to be a practical lower limit on the engine size of 10 MW at present.

The effect is assumed to be constant, as the vessels operating at a high enough engine load when in operation for the power turbine/steam turbine to work efficiently. Note that in reality a slow steaming vessel initially designed for e.g. 80% engine load on main engine would not be able to utilize a power turbine/steam turbine.

The benefit from the measure can be twofold: in terms of reduced fuel consumption on either a main engine equipped with shaft generator or on the traditional auxiliary engines. For simplicity the estimated reduction potential is here given as efficiency gain on the main engine, taking into account this twofold benefit possibility.

Cost of implementation

The installation cost for this measure is estimated at $5,000,000 to $9,500,000 (USD) per ship from the smallest up to the largest installations. There are a lot of costs involved with installing such a system which are more or less independent of size, and a cost element which is modelled linearly with ship size.

There will be some annual maintenance needed, mainly for the boiler, power turbine and/or steam turbine, in order to keep up the performance of the WHR-system. This cost is estimated at around $20,000 (USD) per ship, independent of size, for waste heat recovery systems with steam turbine. For waste heat recovery systems with power turbine $10,000 (USD) is estimated as an annual maintenance cost, and for the combined power and steam turbine system $30,000 (USD) is estimated. It is however recognized that these figures may be in the lower end.

Reduction potential

The reduction potential is estimated at 3% to 8% of main engine fuel consumption.

Other References

1. CO2 abatement potential towards 2050 for shipping, including alternative fuels / Eide et al./ Recent studies have demonstrated a cost-effective potential to reduce the CO2 emissions in the existing world shipping fleet by 15%, and by 30% for the 2030 fleet / 2013
2. MAN Diesel & Turbo / Waste heat recovery system / WHRS for reduction of fuel consumption, emissions and EEDI
3. Air pollution and energy efficiency / IMO energy efficiency appraisal tool
4. Decreasing energy consumption with ABB Waste Heat Recovery System / Description of waste heat recovery system

Air cavity lubrication

The technique is to use air injection on the wetted hull surfaces to improve a ship’s hydrodynamic characteristics. The system, driven by auxiliary engine producing the power, creates an air cushion on the flat bottom part of the ship. Air-cavity systems are already in place today.

Fouling growth on the hull is reduced due to decreased wetted surface when operating an air cavity system, helping to minimize the drag resistance. The benefit from the measure will come in terms of reduced fuel consumption due to hull resistance and therefore the decrease in the main engine load.

Applicability and assumptions

Air cavity lubrication is applicable for new buildings where the maximum reduction potential can be achieved for “low Froude number” ships for which frictional resistance dominates, as bulkers, tankers and containers.

The air cavity system requires installation of additional pumps and piping for the air in addition to changes in the hull shape in order to trap the air and create the air cushion. Depending on the design, such a system may require protected propellers or other means of avoiding air to stream to the propeller.

Air cavity systems will only affect the viscous part of the total resistance. Viscous resistance will account for 50% to 70% of the total resistance on most ships. Note, however, that speed vs. stability considerations should be considered.

Less than 3% of the total ship power is needed to support the air cavity system.

Cost of implementation

The cost of implementation is in the range of 2% to 3% of the new building cost for a vessel.

Reduction potential

Providers of the system claim to be able to achieve 15% to 40% drag reduction and up to 10% fuel reduction on the main engine. The reduction potential for crude and product tankers, and bulk vessels has been assessed at 7% to 10% on the main engine, while for other ship segments it has been assessed at 3% to 5% on the main engine. However, one ship owner in the container segment could not verify the savings, indicating that the reduction potential might be lower.

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool /
2. Silverstream Technologies / Description of the Silverstream system
3. Institute of Marine Engineering, Science & Technology (Imarest) / Air bubbles don’t float Maersk
4. Air Lubrication Drag reduction on Great Lakes Ships / Steven L. Ceccio, Simo A. Mäkiharju / Paper on air lubrication on Great Lakes vessels by Great Lakes Maritime Research Institute / 2012
5. On the energy economics of air lubrication drag reduction / Simo A. Mäkiharju, Marc Perlin, Steven L. Ceccio / Paper on air lubrication and drag reduction / 2012

Hull cleaning

The purpose of underwater hull cleaning is to remove biological roughness or fouling. A build-up of marine fouling can lead to increased drag, resulting in a detrimental impact on a vessel’s hydrodynamic performance and hence the relationship between speed, power performance and fuel consumption.  Fouling, particularly in the case of a prolific build-up of hard or shell fouling like barnacles or tubeworm, can cause turbulence, cavitation and noise, frequently affecting the performance of sonars, speed logs and other hull mounted sensors.

Proper cleaning removes all traces of fouling and does not remove or damage the coating or cause any increased surface roughness. Underwater cleaning is performed either by a diver with brushers or by a remotely operated vehicle (ROV) controlled from land.

Applicability and assumptions

Hull cleaning is applicable for all vessel types and ages. Depending on the degree and type of fouling to be removed a diver can typically clean 200 to 400 m² per hour of flat surfaces (less on the bow and stern areas). The operation will be performed during normal ship stops (bunkering, anchorage, waiting for canal passage, etc.). The fuel reductions depend on the extent to which the hull is fouled.

Cost of implementation

The price of hull cleaning will depend on the selection between a diver and a ROV, in addition to the vessel size. Total cost will be in the range of $5,000 to $50,000 (USD).

Reduction potential

Depending on the degree of marine fouling, vessel size, vessel segment, operation profile and trading areas a reduction in the range of 1% to 5 % on main engine fuel consumption can be expected.

Other References

1. Clean Hull / Hull cleaning brochure with saving potential

Hull coating

The coatings will reduce the resistance of the ship hull through water, and reduce the needed engine power, and thus reduce the fuel consumption.

The savings of applying advanced hull coatings is difficult to measure, but there is no doubt a possible saving by applying high end products. In combination with good hull condition monitoring and maintenance, savings will be achieved. The benefit from this measure will come in terms of reduced fuel consumption and thus a lower fuel cost.

Applicability and assumptions

Hull coating is applicable for all vessel types and ages. Ships are generally recoated every fifth year and by applying high performance coating, hull resistance can be reduced. The reduction potential in frictional resistance will be higher for full bodied ships such as bulkers and tankers. For existing ships there is also a higher potential on segments with a relatively high average ship age. For these segments it is assumed that hull sandblasting will be needed in order to obtain the full effect. The measure will have a capital expense every fifth year when the ship is in dry dock.

Cost of implementation

The cost of hull coating is dependent on the vessel size and segment and will vary in price based on which product one choses. However, a price within the range of $30,000 to $500,000 (USD) can be expected.

Reduction potential

Several tests on commercial ships and laboratories have showed that high end products are able to reduce the overall ship’s resistance by up to 8%. This goes both for silicone based and self-polishing types of coatings. The reduction potential is dependent on vessel size, segment, operation profile and trading areas and is in the range of 1% to 4% on main engine fuel consumption.

Other References

1. Fathom Focus – Hull Coatings for Vessel Performance / The Important Role of the Hull in Ship Efficiency
2. Hullwiper / Fuel saving calculator based on hull cleaning
3. Air pollution and energy efficiency / IMO energy efficiency appraisal tool
4. Third IMO GHG Study 2014 / International Maritime Organization (IMO) / Smith, T.W.P.; Jalkanen, J.P.; Anderson, B.A.; Corbett, J.J.; Faber, J.; Hanayama, S.; O'Keeffe, E.; Parker, S.; Johansson, L.; Aldous, L.; Raucci, C.; Traut, M.; Ettinger, S.; Nelissen, D.; Lee, D.S.; Ng, S.; Agrawal, A.; Winebrake, J.J.; Hoen, M.; Chesworth, S.; Pandey, A. / 2014

Hull form optimization

In general, optimization means finding the best solution with an unlimited number of variables. Ship design is closely linked to optimization and in general the owner has three options when acquiring a new-build when it comes to hull form optimization: accept standard design, modify existing design or develop a new design. The two last options involve optimization for specific service conditions, modification to the forebody and stern shape design and optimization of the vessel hull. Minimizing hull resistance will lead to lower fuel consumption.

While main particulars are generally well optimized across shipyards, there is significant variance in the degree of hull form and propeller optimization. A comprehensive series of model tests and computational fluid dynamic (CFD) assessments are needed to fully optimize a hull form. Shipyards tend to optimize around the specified design draft and speed, while giving less attention to the efficiency at the ballast draft, and little or no attention is paid to partial load conditions.

Applicability and assumptions

Hull form optimization can be applied to all vessel types and ages. There is larger potential for fuel saving where the expected operating profile differs from the standard design. A CFD analysis typically includes three or more iterations of lines refinement and should be carried out with multiple trims and drafts.

Cost of implementation

When considering hull form optimization, it is beneficial to include sister vessels in the CFD analysis to reduce the cost for the fleet. The cost of a full CFD analysis to find an optimum hull form to one specific vessel will be in the range of $150,000 to $500,000 (USD).

Reduction potential

The reduction potential is dependent on vessel size, segment, operation profile and trading areas. A reduction of 4% to 8% on main engine fuel consumption is likely.

Other References

1. Hull form optimization / Overview over most recent hull form optimization related papers from Maritime Research Institute Netherlands

Hull retrofitting

Current operating profiles (speed-draught matrix) for many vessels deviate significantly from the profile or design point that determined the initial design of the vessel. Accordingly, the vessel’s hull profile is not optimized for current operations. For existing vessels, where the degrees of freedom in hull form optimization are limited compared to a newbuilding project, retrofitting of the bulbous bow can bring considerable fuel savings.

Applicability and assumptions

Applicable for tank, LNG carrier, bulk and container vessels operating a large part of the sailing time in off-design conditions, i.e. at other conditions than design draught and contract speed for which the existing bulbous bow is optimized.

It is also possible to optimize the position of the bilge keel and the shape of any thruster tunnels. The bilge keel positioning improves the resistance of the hull by optimizing the positions of the bilge keels. The largest savings potential is for hulls up to about 50,000 DWT and there is no penalty in any loading condition. Bow thruster tunnels can add significantly to the total resistance of the ship. Optimizing the thruster tunnels is relatively inexpensive to implement and may have a significant impact. If the thruster tunnel is redesigned (introducing a scallop) it is also recommended to perform a grid alignment.

Some vessels have fender bars that in some conditions create significant increased resistance. These may be changed for improved performance.

Cost of implementation

For bulbous bow an assumption of $100,000 (USD) fixed cost for the new bulbous bow with optimization, engineering and approval (economies of scale for sister vessels would reduce the fixed cost per vessel). Additional material cost of $250,000 to $700,000 (USD) depending on size. The other retrofit costs are as follows:

• Thruster tunnel optimizing: $10,000 (USD) + detail design and docking cost
• Bilge keel optimizing: $10,000 (USD) + detail design and docking cost

Reduction potential

Reduction potentials are dependent on vessel size, vessel segment and design speed. The following reduction potentials on main engine fuel consumption are expected:

• New bulbous bow: 3% to 5%. Depending on the difference between design speed and average speed according to current operating profile the fuel saving will vary from 3% with >80% of design speed and 5% with <75% of design speed
• Thruster tunnel optimizing: 0.5% to 1%
• Bilge keel optimizing: 0.25% to 1%

Other References

1. DNV GL ECO Retrofit service / How replacement of bulbous bow can increase a vessel’s energy efficiency
2. Force Technology Retrofit – a new bulbous bow / Retrofitting possibilities /

Propulsion Improving Devices (PIDs)

Propulsion improving devices (PIDs) or energy saving devices (ESDs) are different ducts, pre-swirl fins, fin on hull, rudders, caps, contra-rotating propeller (CRP) or other modifications made to the hull or propeller in order to improve efficiency. Depending on the device, the main goal for these devices is to reduce the fuel consumption by improving the flow around the hull or propeller. The three main places to do modifications are in front of the propeller, behind the propeller or do modifications on the propeller or cap. Pre-swirl devices aim to improve the propeller inflow conditions, ducts may improve propulsion efficiency, e.g. by improving the propeller inflow, and post-swirl devices are used to recover parts of the rotational energy in the propeller slip stream.

Applicability and assumptions

Retrofitting measures for propeller and rudder vary in applicability for different vessel types. Wake equalizing and flow separation alleviating devices are best suited to correct known existing hydrodynamic problems and vessels operating at low to medium speeds. They are less effective when the hull geometry has been designed correctly. Pre-swirl devices can be used on all vessel types, mainly for slender and faster vessels, and has to be designed together with the propeller and other relevant post-swirl devices. Naturally, the same applies for post-swirl devices. For more details, see the table below which provides information on different PIDs.

There are some considerations to take when looking at PIDs. It is important to evaluate different devices and identify those devices with the potential to improve efficiency based on the operational profile of the vessel. Computational fluid dynamics (CFD) simulations for the full-scale ship are recommended to evaluate the effectiveness of a propulsion improving device in design. The detailed insight in CFD simulations allows also a better comprehension of why a device is effective or not.

Cost of implementation

PID	Range of application	Estimated cost of implementation
Pre-swirl	Slender and faster vessels, e.g. container and RoRo	$250 000 – $300 000 (USD)
Ducts	Bulky and slower vessels, e.g. bulker, tanker, multi-purpose	$525 000 – $575 000 (USD)
Post-swirl fins – propeller boss cap fins	All segments, especially vessels with high loaded propellers (RoRo, container)	$100 000 – $150 000 (USD)
Wheels – Grim vane wheel	Bulky vessels with space available	$525 000 – $575 000 (USD)
Bulbs – Costa bulb	All segments with slow steaming, especially container	$250 000 – $300 000 (USD)
Twisted rudder	All segments with slow steaming, especially container	$650 000 – $700 000 (USD)
Propeller optimization	All segments with slow steaming, especially container	$250 000 – $300 000 (USD) + material costs of 1.5 t/MW and $7,000 USD/t unless existing propeller is recycled
Advanced propeller design – winglets – Kappel	All segments with slow steaming, especially container	$525 000 – $575 000 (USD)

Reduction potential

A likely reduction potential for various PIDs is in the range of 0.5% to 5% on main engine fuel consumption.

Mounting or exchanging appendages such as pre-swirl or ducts may count for up to 5% in fuel savings, whereas propeller boss cap fins and rudder bulbs, such as Costa bulbs, may each count for up to 2% in fuel savings.

Other References

1. Improving propulsion efficiency / PIDs and other propulsion improving devices explained

Propeller polishing

The measure is related to the condition of the surface of the propeller which influences the efficiency of the propeller. The surface of a propeller will become less smooth due to strain and cavitation damage, whereas growth will start to develop over time. This can be avoided by regular polishing or coating of propeller. It is recommended to perform this measure twice yearly. This has been found to have the optimal balance between cost and effect.

Applicability and assumptions

Propeller polishing is applicable for all vessels and vessel ages. The propeller may be polished twice a year. This is either performed by a diver while the ship is berthed and loading cargo or when the ship is in dry-dock. The fuel cost for the ship will be reduced from improved propeller efficiency since the power loss in the system will be decreased.

Cost of implementation

Depending on the number and the complexity of the propeller(s), the cost of having a diver performing propeller polishing is in the range of $4,000 to $8,000 (USD).

Reduction potential

The reduction potential is dependent on vessel size, segment, operation profile and trading areas. The likely reduction potential of propeller polishing is between 3% to 4% on main engine fuel consumption.

Other References

1. Reductions In Fuel Consumption As A Result Of In-Water Propeller Polishing / Wilkinson, C.P. / The effectiveness of propeller polishing on the reduction in fuel consumption is reviewed from a theoretical viewpoint and compared with a number of actual trials carried out on several types and classes of ships / 1994

Propeller retrofitting

Changed operational profiles with varying speeds often lead to non-optimal propeller designs on existing vessels. These propellers have typically been designed for maximum speed and low cavitation. An upgrade to a high-efficiency propeller can reduce the overall fuel consumption.

Applicability and assumptions

Propeller retrofitting is suitable for all vessel types and ages with slow steaming, especially container and large vessel series. The exchange of the propeller with an upgraded design assures operation at peak efficiency. Included with the price of the propeller itself, a complete analysis to recommend the best-suited propeller for highest efficiency is also included. An engineering analysis should be conducted utilizing computational fluid dynamics (CFD).

Cost of implementation

The cost of propeller retrofitting with CFD analysis and a new propeller is assessed to be in the range of $400,000 to $500,000 (USD).

Reduction potential

This measure typically makes the most sense when combined with additional improvements on machinery and the achieved reduction potential is assessed to be in the range of 2% to 5% on main engine fuel consumption.

Other References

1. DNV GL ECO Retrofit / Overview of different retrofit options
2. DNV GL Energy efficiency finder / Holistic approach to finding applicable energy efficiency measures to a specific vessel type

Cargo handling systems (Cargo discharge operation)

Crude-oil cargo discharges are high energy consuming operations driven by complex machinery systems and the operation involves people in different locations on the vessel. Model-based techniques are utilized in order to assess the performance and improve the operation of the discharge system (from boiler’s primary energy conversion to cargo pumps discharge) based on actual measurements from a discharge operation. This model-based study will include assessment of the overall performance based on an analysis of discharge operational data. Based on the results, it is suggesting improvement strategies and estimation of their potential in savings.

Applicability and assumptions

This measure can only be applied on crude-oil vessels with steam turbine driver cargo pumps, for all ages. These are mainly installed on Aframax or larger tankers. The quality of the results depends heavily on the quality of the measured/transmitted data from the vessel.

Cost of implementation

Including implementation and a monitoring phase the total cost of a project is in the range of $15,000 to $25,000 (USD).

Reduction potential

Depending on the starting point, e.g. how well the operation is optimized before, the total fuel reduction on boiler consumption is in the range of 5% to 15%.

Other References

1. An integrated modelling framework for the design, operation and control of marine energy systems. / Dimopoulos, G.G. and N.M.P. Kakalis / 2010
2. Modelling and optimisation of an integrated marine combined cycle system. / Dimopoulos, G.G., C.A. Georgopoulou and N.M.P. Kakalis /2011
3. Modelling and simulation of marine scrubbers: impact on engine performance / Georgopoulou, C.A., G.G. Dimopoulos and N.M.P. Kakalis / 2011
4. A validated dynamic model of the first marine molten carbonate fuel cell / Ovrum, E. and G. Dimopoulos / 2011
5. Towards a model-based assessment of hybrid marine energy systems / Stefanatos, I., G. Dimopoulos, N.M.P. Kakalis and K.B. Ludvigsen / 2012

Energy efficient lighting system

Use of energy efficient lighting equipment such as low energy halogen lamps, fluorescent tubes and LED (light emitting diode) in combination with electronically controlled systems for dimming, automatic shut off, etc. is continuously developed as the focus on energy and environment has increased. The new technology has been applied only to a limited extent to the shipping industry and standard normal design does not include low energy lighting. Implementing energy efficient light system will in addition reduce the maintenance hours and operating cost.

Applicability and assumptions

LED lighting on Celebrity Solstice, Celebrity Cruise Lines, source: MEPC 68/INF.16

Energy efficient light systems can be installed on all vessel types and ages, where passenger vessels have the highest reduction potential.

The total energy consumed for lighting on a normal merchant ship can be estimated to be 0.25% to 5% of the total electrical power consumed and is believed to be higher for cruise and passenger ships (>10%). Since most energy efficient lighting systems have an equal or longer lifetime than normal lighting systems, the additional operational costs are set to zero.

Cost of implementation

Additional cost of $100,000 (USD) compared to the traditional lighting installations on normal ships and $200,000 to $1,000,000 (USD) on passenger and cruise ships.

Reduction potential

The emission reduction potential is estimated from the total auxiliary engine consumption on normal merchant ships and is assessed to be in the range of 0.25% to 5%.

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Frequency controlled electric motors

Many of the auxiliary systems on board are in continuous operation, like seawater and freshwater pumps, fans, compressors, etc. Normally these are designed for full speed operation and high air and sea water temperature. This equipment is hence over dimensioned for the operational pattern of the fleet as the need for full capacity is in the range of 25% to 45% of the operating time, and can be higher for selected vessel types.

Traditional electrical motors cannot vary their motor load based on the actual demand and, therefore, the motor runs on a too high load most of the time. Frequency converted motors will regulate the frequency in order to adapt the motor load to the actual need at all times. Then, the total energy consumed by all the electrical motors on board can be reduced significantly. This technology can be applied to all electrical motors on board, but normally will be applied to motors over a certain size.

Applicability and assumptions

It is assumed that motors with frequency converters can be installed for all electrical motors on board for all ships in each included segment and that there are no limitations on type and size of such motors, independent of vessel age.

A frequency converter will enable the electrical motors on most equipment on board to run on part loads instead of on/off as is the case today.

 

Cost of implementation

Estimated extra cost for installing frequency controlled electrical motors compared to traditional motors are set to $100 to $200 (USD) per kW installed auxiliary engine power on board. It is assumed that the installation cost will decrease over time to half by 2030 due to the increased demand, more modern technology and more producers of ship equipment.

For operational costs it is estimated an extra cost of $3,000 (USD) per year for maintenance of the more sophisticated equipment compared to when standard equipment is used.

 

Reduction potential

The reduction potential is estimated at 2% to 10% of the total fuel consumption for auxiliary engines.

The effect is assumed not to increase over time as this is fairly standard equipment which has been available for shore applications for many years.

 

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool
2. ABB / Using Variable Frequency Drives (VFD) to save energy and reduce emissions in newbuilds and existing ships

Fixed sails or wings

Fixed installations on the ship in the form of a flexible sail, rigid sail or turbosail can make use of the wind to replace some of the propulsion power needed. All possibilities have pros and cons and must be chosen to best suit the ship type, trade and size. The savings are highly dependent on the wind conditions in which the ship operates.

Applicability and assumptions

These initiatives are only applicable for ships with enough space and therefore not container ships. There is no vessel age restriction for fixed sails or wings. Stability due to the high placement of additional weight and force from the sails is not assumed to be an issue for the ships. Prices are based on ships not needing changes in design in order to fit the masts. The masts and sails are assumed to have a potential of providing about 710 kW of power per installed mast which will result in a forward thrust and reduce the power needed from the main engine. The effect of each mast is assumed to improve to 1,200 kW in 2020 and keep constant after that. The effect of each mast will vary with the prevailing wind and therefore will not be effective most of the time. It is assumed that the sails only will be operational 15% of the time. The effect and applicability of this measure is also dependent on operating speed (most useful in the lower speed range).

Cost of implementation

The price per mast (including installation) is expected to decrease dependent on how many masts are installed on board. Thus, the capital cost involved will range from $170,000 to $300,000 (USD) per mast installed.

Reduction potential

The reduction potential is dependent on vessel size, segment, operation profile and trading areas. The likely reduction potential is estimated to be in the range of 1% to 10% on main engine fuel consumption.

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Flettner rotors

Flettner rotors are vertical cylinders which spin and develop lift due to the Magnus effect as the wind blows across them. Flettner rotors must be mechanically driven to develop lift and propulsion power, and manoeuvrability is restricted by wind speed and direction. Working on a ship, the force created will generate thrust. On board vessels, such rotor propulsion are often called Flettner rotors after the German innovator who was the first to install such a system on board a ship at the beginning of the 1920s. Flettner rotors may reduce the energy consumption of a ship, but they cannot be used as main propulsion.

Applicability and assumptions

Flettner rotors are a supportive propulsion system possible to retrofit on existing vessels, primarily for the ships and trades that benefit most from wind assisted propulsion. The rotating cylinders generating thrust are applicable for vessels with a sufficient free deck-surface and it is important that no objects block the accessibility to free wind. Rotating cylinders generating thrust are suitable for numerous ship segments; for example, tankers, some bulk carriers where rotors will not interfere with the required air-space for loading and unloading, general cargo carriers, and some RoRo ships. Container ships may be evaluated for a design with elevated/retractable rotors mounted above the container cargo. Operational height limitations must be taken into account, for example, in case of interfering with operational related structures or infrastructural barriers related to the route.

The rotating cylinders generating thrust mainly generate forces in the horizontal plane, forward and sideway forces. To make sure the seagoing properties of the vessel remain good, it must be prepared and planned because the healing movement influencing the stability and the strength of the cylinder foot must be properly supported as it is subject to high stresses.

The Flettner rotor principle in general is working in sideways winds, and depends on wind and vessel speed. The effectiveness of the rotors is therefore dependent on trade route and weather conditions.

Cost of implementation

The range of cost for a Flettner rotor is $400,000 to $950,000 (USD) depending on the model (size) of the rotor.

Size of a typical delivery with multiple rotor sails starts from $1,000,000 to $3,000,000 (USD).

Reduction potential

The reduction potential of a Flettner motor is 3% to 15% on main engine fuel consumption depending on vessel size, segment, operation profile and trading areas. Some have reported reductions as high as 35%, but for a reduction potential in general, this is seen as high.

Other References

1. Wind rotor for ships / Success story of sea trial for Norsepower
2. Evwinds / The rotor sails on the ENERCON-developed „E-ship 1“ allow operational fuel savings of up to 25% compared to same-sized conventional freight vessels
3. Air pollution and energy efficiency / IMO energy efficiency appraisal tool
4. The use of Flettner rotors in efficient ship design / Pearson, D.R. / 2014 / London, The Royal Institute of Naval Architects

Kite

The kite works from wind power which is transferred to the ship and results in less engine power needed to move the ship. The kite will under normal conditions generate a pulling force on the ship, which can be translated into an equivalent engine power generated. One example of a ship with kite is the MV “Beluga” where a test installation has been used since 2008.

Applicability and assumptions

The system works best for ships over 30 metres and in speeds less than 16 knots, independent of vessel age. Another important factor is the amount of time the kites can be used and yield an effect. Due to prevailing winds and other limitations of the kite system, it is assumed that the kites can only be used 20% and 30% of the time for small and large ships, respectively. Kites are more favourable on long international trades where larger ships tend to trade.

Table 1 Overview of size of kite and power generated

Size of kite [m2]	Power generated [kW]
160	600
320	1 200
640	2 500
1 280	4 900
2 500	9 600
5 000*	19 200

* Assumed not to be available until 2020

The larger the ships are the bigger a kite they can use, e.g. for crude oil tankers only a VLCC can use the 5,000 m² kite.

Cost of implementation

The main cost elements for the kite will be purchase, installation and operational expenses, and these are expected to increase with the size of the kite as shown in the table below.

Table 2 Overview of size of kite and installation cost

Size of kite [m2]	Purchase cost [USD]
160	280 000
320	480 000
640	920 000
1 280	1 755 000
2 500	2 590 000
5 000*	3 420 000

Reduction potential

The reduction potential is dependent on vessel size, segment, operation profile and trading areas. The expected reduction potential is in the range of 1% to 5% on main engine fuel consumption.

Other References

1. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Solar panels

Solar panels are devices that convert light from the sun into electricity, thereby the name solar panels. Solar panels on ships are not very common at present, but some installations have been done over the last years.

Applicability and assumptions

Solar panels are applicable for all ages of vessels trading in areas with sunlight. Further, to produce electricity from solar panels a large area for installation is required and therefore only ships that are not dependent on deck space can utilize the system (e.g. car carriers).

In order for solar panels to work onboard ships and in a relative harsh environment, the panels have to be extra sturdy compared to land based installations.

Solar panels on vessels will consist of several solar panels creating one large system. The efficiency of the module represents the conversion of the energy in the light hitting the surface of the module to electricity at its output. Solar modules are rated at an irradiance of 1000 W/ m² and at 25 Degrees C (and an air mass of 1.5) as the Standard Test Conditions. This means for instance that a 150W module will produce 150W at noon on a nice sunny day that is not too hot.

However, the capacity factor that represents the percentage of the installed capacity of generation to the energy which is actually delivered over a period of time ranges from 10% to 30%.

The solar panels on vessels are installed to produce electricity and will be used to supplement the diesel generators and thus reduce the power required from these units. The solar power units can produce energy both at sea and in port, but only during daylight and therefore the solar panels are set to only produce power 50% of the time. Moreover, solar panels produce power also in cloud cover though not at full capacity.

Cost of implementation

The solar panel technology is expected to become less expensive over time, but the panels are unlikely to become much more efficient or less space consuming. The cost of solar modules themselves has dropped considerably over time.  They are presently approximately $0.6 (USD) per Watt of installed capacity.  A solar system requires additional equipment beyond the modules. This includes cables, inverters (to convert DC power to AC) and the mounting structure. An estimated system for vessel installation price is set to $2.8 to $3.4 (USD) per watt, meaning that an installation of 150 kW would cost from $420,000 to $450,000 (USD). This value is expected to decrease over time, based on what has been seen for land based installations.

Reduction potential

The estimated reduction potential for solar panels is 0.5% to 2% on auxiliary engine fuel consumption.

Other References

1. Pv magazine / Japan: Green transport ship sets sail with Solar Frontier CIS panels
2. Ship & Bunker / K-Line Launches Eco-Ship Featuring Solar Power Technology
3. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Autopilot adjustment and use

Autopilot is the use of an automatic system to control the rudder on the vessel. Use of autopilot can reduce the fuel consumption by smoothing out the large angle rudder movements used to hold a steady course. Efficient and adaptive autopilot operations allow small deviations to course-line, but will use fewer and smaller angle rudder movements to maintain the course-line. This decreases the rudder movement and consequently reduces fuel consumption.

Applicability and assumptions

Autopilot adjustment and use is applicable for all vessel types and vessel ages.

Autopilot optimization is quick to implement, assuming that autopilot is already installed on all vessels. However, it will need some effort to check whether right settings have been applied by the crew and the complexity of the system is low due to adaptive self-learning systems on board.

For optimal adjustment and use of autopilot, best practice in shipboard procedures must be implemented (including recommendation on optimal number of rudder movements and angles for different sea conditions). The crew must be properly trained to achieve the saving potentials.

Cost of implementation

There is no cost of implementation assuming that autopilot is already installed.

Reduction potential

Estimated reduction on main engine fuel consumption is 0.25% to 1.5%, through effective autopilot and rudder settings.

Other References

1. Marine Insight / 10 Things to Consider While Using Auto-Pilot System on Ships
2. Ship Efficiency: The Guide / Fathom / Ship energy efficiency with focus on ship design, propulsion, machinery and strategies and energy management software / 2013

Combinator optimizing

For controllable pitch propeller an operational measure is to run the system using a “combinator curve” with optimized pitch settings and propeller speed, making it possible to operate the total propulsion system with optimum efficiency.

Applicability and assumptions

Combinator optimizing is applicable for vessels with controllable pitch (CP) propeller respective of ship type and age.

Combinator curves take into account engine requirements, propulsion efficiency, cavitation patterns in different conditions and the mission profile of the vessel. The curves are applied for improving the propulsive performance for vessels with (CP) propellers.

The following points are procedures for improving the propulsive performance by applying combinator curves:

• Evaluate the current combinator curves and make sure that curves for different operational modes exist, especially for AHTS vessels
• Run simulations and develop new curves if you have any reason to believe that the existing curves are not optimized for your operations
• Make sure that the optimum combinatory curves always are used
• Evaluate and document the effect of optimal usage of combinator curves
• Train crew on expected ship speed and thrust relation

Cost of implementation

There are no costs of implementation.

Reduction potential

The expected fuel reduction is 0.25% to 1% of total fuel consumption on main engine for all modes at sea.

Other References

1. The ship power supplier / Technology guidelines for efficient design and operation of ship propulsors
2. Air pollution and energy efficiency study series / Study on the optimization of energy consumptions as part of implementation of a ship energy efficiency plan (SEEMP)

Efficient DP Operation

Some vessels operate with dynamic positioning, DP, meaning the vessels remain stable at the same position independent of external effects such as wind, waves and currents. DP operations form an integral part of offshore vessel operations, however, with different emphasis for the different stakeholders. IMO, Flag States, Classification Societies and Charterers set stringent requirements regarding e.g. equipment capabilities, redundancy, system testing and training of officers. However, there is little focus on efficient utilization of equipment. By focusing and implementing tasks for efficient DP operation, fuel savings can be gained.

Efficient DP operation is to improve the operation of when a vessel is in DP mode, or reduce the time operating in DP. Improving DP operation should be undertaken through identifying and establishing a common approach/understanding regarding DP operation within the company, recognizing variations in operations between the different segments.  This should emphasize the importance of standardizing DP operation throughout the fleet.  It should also clearly state expectations to the fleet in terms of future DP operation including clear instructions to the vessels on how to implement on board.

Applicability and assumptions

Efficient DP operation is applicable for all ages of vessels with a DP system. DP systems vary greatly depending upon a number of differentiation factors, for example the age of a vessel, leading to different functionalities and capabilities of equipment. Additionally, equipment varies between different manufacturers. However, the main functionalities of the equipment should be standardized for all. Due to the complexity of the systems and also to the importance of position keeping capabilities, the specifications and functionality of DP systems are tightly controlled.

With regards to fuel efficiency, it is critical that operations are optimized to a large extent as possible as offshore vessels spend a large percentage of time operating in DP mode.

For efficient DP operation, it is beneficial to develop a company policy and guidelines regarding Energy Efficient DP operation. The guidelines should emphasize the importance of standardizing DP operation throughout the fleet. It should also clearly state expectations to the fleet in terms of future DP operation including clear instructions to the vessels on how to implement. A guideline may include, depending on type of operation, modes, configuration and installed DP system, the following:

• Utilize Activity Operational Planning to establish the Safest Mode of Operation, Task Appropriate Mode and Activity Specific Operating Guidance, and subsequently a framework for when to utilize each in order to maximize energy efficiency within DP operations.
• Open/Closed Bus operations: Depending on equipment class, see IMO MSC/Circ.645, the open/closed bus operations should be evaluated whether the operation may be conducted in a more efficient manner (i.e. shutting down elements of the system if not required).
• Implement drifting as alternative to DP operation if appropriate: This could be implemented primarily on board OCV vessels.
• Implement anchoring as alternative to DP operation: It is recognized that this recommendation is limited to areas where depth of water facilitates.
• Optimizing gain settings: Standardizing and placing focus on utilization of gain settings can realize energy savings with a minimum corresponding loss of position integrity.
• Use of relaxed DP modes: Only relevant for those vessels with the functionality existing in the equipment on board. Green DP may be utilized as a more energy efficient mode of operation in operations where a lesser degree of position accuracy is required, but the vessel is still required to operate in the DP mode.
• Utilizing manual control in clearly defined scenarios: In certain scenarios the use of manual control may assist with a reduction in consumption compared with operating in DP mode. For example, using the main propulsion to maintain position rather than operating in DP (vessel steams slowly into the wind making way and maintaining heading through use of the engine rather than thrusters).

Cost of implementation

There are no direct costs related to efficient DP operation. However, there might be costs related to training of crew to improve the performance, production of guidelines or software tools to track the performance of this as a measure.

Reduction potential

The assumed reduction potential is 1% of total ship fuel consumption. However, it is important to highlight that the reduction potential in DP is 2% to 5 % of the fuel consumed in DP, as the time in DP varies significantly for different vessels.

Other References

1. IMO MSC/Circ. 645 / Guidelines for vessels with dynamic positioning systems
2. Kongsberg K-POS / Dynamic positioning. Optimizing complex vessel operations

Speed management

Speed management includes different aspects of adjusting and planning for optimal vessel speed and engine load.

A vessel’s fuel consumption for propulsion is a result of energy needed to push the vessel through the water at the given vessel speed through water. This relationship, between fuel consumption versus vessel speed, is typically an exponential one. As a rule of thumb assuming that engine power follows the cube of speed, a displacement ship with 10% speed reduction reduces the power need (resistance) and coherent fuel consumption by 27%. However, to assess the total fuel saving on a voyage basis one has to take into account the added time it takes to sail a given distance due to lower speed, yielding a total fuel saving of approx. 19%. For a selected open hatch cargo vessel at 56 000 DWT presented in Figure 1, a 13% speed reduction saved almost 40% of the daily fuel consumption.

Applicability and assumptions

Speed management is applicable for all vessels and at all ages.

Speed planning

With basis in the exponential relationship between fuel consumption and power (speed), a vessel sailing with variable speed will usually, for same distance and duration, consume more fuel compared to sailing with constant speed, ref. real case from AIS analysis Figure 2. This is especially true for all diesel-mechanic propelled vessels, including most diesel-electric; however, there are examples of cases where diesel-electric vessels have engine sizes, numbers and specific fuel consumption characteristics that yields sailing with variable speed more favourable.

Optimum speeds with regards to fuel efficiency can however often be challenging due to scheduling requirements from the charterer and other influences. The consequence of strictly enforcing a speed, whether it is variable or constant, can also contradict the weather as vessels may need to “fight the waves” in harsh weather and unnecessarily reduce the power when current and wind are favourable.

 

Improved planning, better use of vessel specific knowledge, weather forecasts and communication between charterer, port and vessel can improve the speed profile during a voyage and consequently reduce the fuel consumption.

 

Slow steaming/ECO speed

By simply reducing the speed by 10%, the fuel consumption can be reduced by almost 20%. Slow steaming or ECO speed is the practice of significantly reducing the sailing speed to reduce fuel consumption not only for parts of a voyage, but for a period of voyages, a group of vessels or for a whole fleet. Speed reduction is a strategic measure as opposed to day-to-day speed adjustment depending on expected time of arrival (ETA), weather, currents etc. Large reductions can be made by sailing slower as the fuel consumption curve is exponential subject to speed. Slow steaming is relevant for all vessel types and has highest reduction potential for vessels in long transits. As a constant measure over longer periods slow steaming can inflict increased wear and tear on the engines as very low loads are experienced. Adjustments and due planning and care has to be made related to auxiliary blower operation, heat loads, lubrication and cylinder oil, etc. Significantly lower loads, i.e. at 20% to 50% MCR, can on the other hand also open up for savings potential on the auxiliary systems designed to support the engines when running at full load.

Cost of implementation

There are no investment costs, but this may impact the total revenue due to longer sailing time.

Reduction potential

The reduction potential is 10% to 50% of ship main engine fuel consumption.

The reduction potential of slow steaming is amongst others dependent on which speed the vessel sailed at before it started slow steaming and which speed it is sailing at when slow steaming.

Other References

1. DNV GL Energy efficiency finder / Holistic approach to finding applicable energy efficiency measures to a specific vessel type
2. Marine Insight / The Guide to Slow Steaming On Ships
3. Slow Steaming in Container Shipping / Meyer et. al / Overview of the slow steaming history as well as the widely assumed coherence between a ship’s speed and its fuel consumption / 2012
4. Kongsberg Vessel performance optimizer / Paper on cost efficient vessel operation
5. Regulated Slow Steaming in Maritime Transport / An assessment of Options, Costs and Benefits
6. Air pollution and energy efficiency / IMO energy efficiency appraisal tool

Trim and draft optimization

The trim and/or draft of the ship influences the hull resistance and therefore the fuel consumption. In general limited regard to optimal trim and draft is taken when loading the ship and therefore optimal conditions will most often not be achieved. By actively planning cargo loading, and thereby optimizing the trim and draft, one can save fuel and reduce the emissions accordingly.

Applicability and assumptions

Trim and draft optimization is applicable for all vessel types and vessel ages. Some vessels have less flexibility regarding trim as, for example, cruise vessels which are designed for passenger comfort and facilities for the passengers. Further, full-body ships where resistance from viscous friction is higher than wave friction (e.g. tank and bulk) will generally have a less reduction by optimizing the trim and draft and similarly for ships with limited ballast flexibility.

In order to be able to optimize the trim and draft additional equipment is required such as a better loading computer or a dedicated trim optimizer. In addition, the crew need training in the use of such equipment.

Better trim and draft will reduce the resistance and therefore less engine power is required which leads to a lower fuel consumption.

Cost of implementation

The installation of system and training of crew has been estimated at $15,000 to $75,000 (USD) per ship depending on type of system where easy trim systems are less expensive than complicated trim software. Once the equipment is installed, there is no additional operational cost.

Reduction potential

Optimizing the trim and draft has been estimated to reduce the fuel consumption by 0.5% to 3% on main engine fuel consumption for most ship types, although for ships which often trade in partial load conditions (e.g. container, ro-ro) the effect can be up to 5%. These numbers are based on full scale tests and detailed calculations performed on a number of different ships in different trades.

Other References

1. DNV GL ECO Assistant / Effective trim optimization
2. IMO Train the Trainer (TTT) / Course on Energy Efficient Ship Operation, Module 4 – Ship Board Energy Management
3. DNV GL Energy efficiency finder / Holistic approach to finding applicable energy efficiency measures to a specific vessel type

Weather routing

The weather (wind and waves) will together with ocean currents influence the power needed to propel a ship at a given speed over ground. Therefore, it is important to take these factors into consideration when planning a voyage and to try to minimize the negative influence.

Applicability and assumptions

The longer the voyages are the more route choice flexibility the ship has in order to avoid unwanted weather conditions. Also longer voyages most often include time spent in unsheltered waters where the influence from weather is making weather routing important. Therefore, the biggest potential could be realized in intercontinental trades and for larger ships.

All ships at all ages can potentially install the system, and therefore it is assumed that the entire fleet can install the measure. However, for existing ships, some ship segments (e.g. large container and ro-ro) have to a certain degree already implemented weather routing and, therefore, have a lower potential for fuel consumption reduction. This is also assumed to be the case for new ships coming into service in this period.

The choice of most fuel efficient route must be balanced against the safest route and quickest route.

In order to improve the weather routing a new system will have to be installed on board all ships. This system is assumed not to become standard in the future and will come at a premium for the time period studied.

The benefit from the measure will come in terms of reduced fuel consumption due to reduced resistance from wave and wind. There might also be a benefit from less fatigue and weather damages.

Cost of implementation

The system is estimated to cost $15,000 (USD) per ship to install and in addition an annual subscription of $3,000 (USD) per ship is needed to keep the software up to date and get the latest weather information.

Reduction potential

The potential has been assessed to between 0% to 5% on main engine fuel consumption dependent on ship size and type and the typical trade for the different ship segments.

Other References

1. IMO / Ships’ routeing
2. IMO resolution A.893(21) / Guidelines for voyage planning
3. IMO Train the Trainer (TTT) / Course on Energy Efficient Ship Operation, Module 3 – From Management to Operation
4. Air pollution and energy efficiency / IMO energy efficiency appraisal tool