Improving Energy Efficiency Through Design And Operation Engineering Essay

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The design technology is considered a short to medium term, this technology can lead to up to 30% save in energy, yet it has to be considered during ships newbuildings, however some of these optimizations can be applied to existing ships.

Optimizing the hull and superstructure:

The latest technology to reduce the frictional resistance of the hull surface is the air bubble system which blows air bubbles underneath the ship's hull, subsequently reducing fuel consumption and improving fuel efficiency. On the other hand optimizing the superstructure leads to a reduction in power consumption of 2 to 5%.

Optimizing the propulsion systems:

Enhancements of the propeller by using propeller vanes is expected to improve the power consumption by 10%, on the other hand, coaxial contra rotating propellers can reduce power consumption from 6% to 20%. Moreover, ducted propeller has the potential to reduce power consumption between 5to 20%, while Pre-swirl devices can reduce power consumption up to 8%. Furthermore, asymmetric stern reduces power consumption by 1 to 9%, integrated propeller and rudder units have the potential to reduce power consumption by 5%.

In general optimization of the Hull and propeller can reach up to 30% reduction in power consumption.

Improving Energy saving by operations:

Fleet management is another important tool to reduce ships emission and improve energy efficiency; it deals mainly with Voyage optimization, Energy management, and ship maintenance.

Voyage optimization:

With the existing knowledge ships can increase their energy efficiency by making wind and current work in their favor this can lead to less fuel consumption. Also, avoiding unnecessary ballast and determining the correct trim improves energy efficiency; voyage optimization can result in substantial saving in energy.

Speed reduction

Reducing ships speed by 10% in speed will reduce energy consumption and GHG by 19%.

Energy management:

Optimizing ventilation and air conditioning and using energy based on necessity. Also, using automation techniques for temperature, pumps, ventilation, and lighting control can save up to 10% on auxiliary power which corresponds to 2% in fuel consumption.

Ship maintenance:

Right hull coatings reduces power consumption by 1% while maintaining the hull would lead to 5% power saving.

Engine upgrades reduces fuel consumption and GHG emissions by 3%, and reduces NOx emissions by 20 to 30%, in addition to the reduction in smoke and carbon monoxide emissions.

Propeller maintenance and upgrades can reduce the fuel consumption 3%.

Renewable energy sources:

The use of wind power:

Traditional sails, Solid wing sails, Kites and Flettner type rotors were proposed. However, wind power can only be considered as a support to the main propulsion and is useful for medium to long term.

The creation and use of solar power:

The power created by this technology is not enough for the running of the ship, also, no solar power can be created at night time, and there is a limit to how much can be stored during the day time moreover, this technology is the least cost effective technology.

The creation and use of wave energy:

This technology is not feasible due to its complexity and has very limited energy thus it is not regarded as a promising technology.

Shore created energy:

Shore created energy is considered not feasible due to the need of such energy on land; however it is very useful for cold ironing.

Using fuels with less emissions:


There is still some uncertainty to the use of biofuels in ships engines due to the lack of studies regarding the net benefit of bio-fuels, currently biofuels can be refined into high quality fuel however the process (refining) in itself creates additional emission, and is more expensive than oil.

Liquefied natural gas (LNG)

Liquefied natural gas is the most suitable alternative to current diesel oil, due to the lower CO2 emission and considered a clean fuel, with no sulphur consequently eliminating Sox and reducing NOx emission by 90% and eliminates particular matters as well, also, LNG is cheaper than the diesel oil.

A challenge to using LNG is that it requires increasing the storage size to three times of that of diesel, and can only apply to newbuildings.

Nuclear power:

Nuclear power has many advantages when it comes to GHG in addition it is feasible and is used by some ships and military ships as well. However and due to different reasons (e.g., social, political, security, environmental) it is not viable.


The use of hydrogen currently is not viable due to the high cost involved and both storage and handling of the hydrogen.

Emission-reduction technologies:

Emission-reduction options for NOx

The reduction can be achieved by Fuel modification, charge air, combustion process modification and the Treatment of the exhaust gas by selective catalytic reduction (SCR).

Emission-reduction options for Sox

Scrubbers can be used to remove SOx, however, this will lead to reduction in exhaust gas temperature, while Selective catalytic reduction need high temperature thus combining the two is not feasible.

Emission-reduction options for PM

In addition to what was mentioned earlier (PM) can be further reduced by using low-sulphur fuels.

Emission-reduction options for CO2 emission:

Reducing emission in general leads to the reduction of CO2, by combining the technologies mentioned above will result in significant reduction of CO2 emission.

General Potential reduction in the power used in existing typical ships Measure Energy management and efficient ancillary systems Power used by auxiliary systems 10%

Voyage opt Power used by main engines 2%

Propeller upgrade and improved maintenance Power used by main engines 2%

Hull maintenance Power required overcoming frictional resistance10%

Engine de-rating and upgrade Power used by main engines1%

Potential reduction in power used, and CO2e emitted from, "state of the art" new designs in 2008

Measure Engine energy Recovery Power wasted via the exhaust 17%

Propeller energy recovery Power wasted due to rotational losses 50%

Hull optimization Power used to overcome wave generation 10%

Design optimization Power used to overcome air resistance 10%

Potential reduction in power used, and CO2e emitted, from projected "state of the art" new designs in 2022

Measure Engine energy recovery Power wasted via exhaust 17%

Propeller energy recovery Power wasted due to rotational losses 60%

Hull optimization Power used to overcome wave generation 15%

Hull coatings Power used to overcome frictional resistance 5%

Design optimization Power used to overcome air resistance 10%

Appendix I

The International Council on Clean Transportation recommendations to reduce the GHG (




- Short term:

° Lower fuel sulfur level in SOx Emission Control Areas (SECAs) from 1.5% to 0.5%.

° Include SOx /PM related health effects in addition to impacts on air, sea, and land as justification for SECA.

° Expand SECA program to high ship-traffic areas in Mediterranean, Pacific Rim and North Atlantic.

° Regional limits in coastal areas, inland waterways, and at ports.

- Medium term:

0.5% sulfur fuel globally

- Long term:

Harmonization with on-road diesel fuels (500 ppm to 10-15 ppm over time)

- International standards (IMO)

New engines

- Short term:

° NOx standards 40% percent below current IMO standards (2000 level).

° PM standards

° Encourage new technology demonstration.

- Medium term:

° NOx standards 95% percent below current IMO standards (2000 level)

° PM standards further reduced

° Encourage new technology demonstration

- Long term:

Encourage the use of advanced technologies, especially near-zero emission technologies in promising applications.

- International standards (IMO)

New vessels

- Short term:

° Adopt international requirements for shore power standardization.

° All new ships built with shore-side electricity capability especially cruise ship and ferries.

- Long term: Promote the use of advanced vessel design concepts in promising applications

- Preferential contracting of cleanest carriers.

- Environmentally differentiated fees and charges.

- International regulation (IMO).

Existing vessels and engines

- Short term:

° Adopt emissions performance standards by vessel class and engine characteristics based on demonstrated retrofit potential.

° Study feasibility and potential impact of programs to promote early ship retirement and environmentally sound disposal.

- International standards (IMO)

- Preferential contracting of cleanest


- Environmentally differentiated fees and charges.


- Short term:

° Develop GHG emission inventory and fleet baseline

° Market-based measures for vessels.

° Implement fuel economy standards by vessel class and engine characteristics for new vessels.

- Medium term:

Implement fuel economy standards by vessel class and engine for existing vessels.

- Preferential contracting of cleanest


- Environmentally differentiated fees and charges.

- Cap and trade program for shipping sector only.

- International standards (IMO).

At port

- Short term:

Select strategy that provides

maximum emissions reduction benefits depending on local fuel availability and environmental performance of electricity


° Shore-side electricity

° Lowest sulfur on-road fuel and NOx and PM after-treatment.

- Medium term: Market-based measures to promote low- or non-carbon energy sources to supply shore-side electricity for docked ships

- Port authority requirement.

- Preferential contracting of cleanest


- Environmentally differentiated fees and charges.