Posted: August 14th, 2022

Fuel Efficiency Improvements for Shipboard Diesel Engines

Fuel Efficiency Improvements for Shipboard Diesel Engines

Fuel efficiency is a key factor for the economic and environmental performance of ships. Fuel efficiency can be improved by various technical and operational measures, such as optimizing the design of the ship and its components, using waste heat recovery systems, implementing energy management plans, and applying alternative propulsion methods. In this blog post, we will review some of the recent developments and innovations in these areas, and how they can help ship owners and operators reduce their fuel consumption and emissions.

Design Optimization

One of the main technical measures to improve fuel efficiency is to optimize the design of the ship and its components, such as the hull, the propeller, and the engine. The design optimization aims to reduce the resistance and friction of the ship in the water, and to increase the propulsion efficiency and power output of the engine.

One of the tools to achieve design optimization is the Energy Efficiency Design Index (EEDI), which is a mandatory regulation adopted by the International Maritime Organization (IMO) in 2011. The EEDI requires a minimum energy efficiency level per capacity mile (e.g., tonne mile) for different ship types and sizes. The EEDI is expected to stimulate innovation and technical development of energy-efficient technologies for new ships, as it is tightened incrementally every five years until 2025 and onwards, when a 30% reduction in CO2 emissions compared to a reference line is mandated for applicable ship types.

Some of the technologies that can help improve the EEDI of new ships include:

– **Hull optimization**: This involves designing the shape and form of the hull to minimize drag and resistance in the water. Hull optimization can also include applying coatings or paints that reduce friction or fouling, or using devices such as fins or bulbs that modify the flow around the hull.
– **Propeller optimization**: This involves designing the shape, size, pitch, and number of blades of the propeller to maximize thrust and minimize losses. Propeller optimization can also include using devices such as nozzles or ducts that enhance the propeller performance, or using contra-rotating propellers that reduce rotational losses.
– **Engine optimization**: This involves designing the engine to achieve high efficiency and power output at various load levels. Engine optimization can also include using advanced technologies such as common rail injection, variable valve timing, turbocharging, or dual-fuel systems that allow the use of alternative fuels such as liquefied natural gas (LNG).

Waste Heat Recovery

Another technical measure to improve fuel efficiency is to use waste heat recovery systems that capture and utilize the heat energy that is otherwise lost from the engine or other sources on board. Waste heat recovery systems can convert the waste heat into useful forms of energy, such as electricity, steam, or hot water, that can be used for various purposes on board, such as lighting, heating, cooling, or propulsion.

One of the common types of waste heat recovery systems is the steam-based combined cycle, which uses a steam turbine to generate electricity from the exhaust gas of the engine. This system can improve the overall efficiency of the ship by up to 10%, depending on the engine type and load. Another type of waste heat recovery system is the organic Rankine cycle, which uses an organic fluid instead of water to drive a turbine from a lower temperature heat source, such as the jacket water or charge air cooler of the engine. This system can improve
the overall efficiency of the ship by up to 6%, depending on the heat source and load.

Energy Management

A third measure to improve fuel efficiency is to implement operational measures that optimize the use of energy on board. Operational measures can include planning optimal routes and speeds, adjusting trim and ballast, maintaining hull and propeller condition, monitoring fuel consumption and performance indicators, and training crew members on best practices.

One of the tools to implement operational measures is the Ship Energy Efficiency Management Plan (SEEMP), which is another mandatory regulation adopted by IMO in 2011. The SEEMP requires ship owners and operators to develop a plan for improving energy efficiency through various measures that are specific to each ship. The SEEMP also requires regular monitoring and evaluation of the plan’s implementation and results.

Another tool to implement operational measures is the Carbon Intensity Indicator (CII), which is a new regulation adopted by IMO in 2021. The CII reflects
the operational energy efficiency of ships, building upon fuel oil consumption from
the IMO Data Collection System (DCS) and
the SEEMP as a management tool. CII is mandatory for ships of 5,000 gross tonnage
and above. The CII rating ranges from A (best) to E (worst), based on a comparison
of actual annual CO2 emissions per transport work with required annual CO2 emissions per transport work. Ships rated D for three consecutive years, or E, will have to submit a corrective action plan to demonstrate how they will improve their rating.

Alternative Propulsion

A fourth measure to improve fuel efficiency is to use alternative propulsion methods that reduce or replace the use of fossil fuels. Alternative propulsion methods can include using renewable energy sources, such as wind, solar, or wave power, or using hybrid or electric systems that store and deliver energy on demand.

Some of the technologies that can enable alternative propulsion include:

– **Wind-assisted propulsion**: This involves using devices such as sails, kites, rotors, or wings that harness the wind power to provide additional thrust and reduce fuel consumption. Wind-assisted propulsion can reduce fuel consumption by up to 20%, depending on the wind conditions and the ship type and speed.
– **Solar power**: This involves using photovoltaic panels that convert sunlight into electricity that can be used for various purposes on board, such as lighting, heating, cooling, or propulsion. Solar power can reduce fuel consumption by up to 5%, depending on the solar irradiance and the ship type and size.
– **Wave power**: This involves using devices that capture the kinetic or potential energy of the waves and convert it into electricity that can be used for various purposes on board. Wave power can reduce fuel consumption by up to 10%, depending on the wave conditions and the ship type and speed.
– **Hybrid systems**: This involves using a combination of different power sources, such as diesel engines, batteries, fuel cells, or supercapacitors, that can be switched or combined to optimize the energy efficiency and performance of the ship. Hybrid systems can reduce fuel consumption by up to 30%, depending on the power sources and the ship type and load.
– **Electric systems**: This involves using batteries or fuel cells as the main or sole power source for propulsion and other purposes on board. Electric systems can eliminate or minimize the use of fossil fuels and emissions, depending on the source of electricity generation. Electric systems are suitable for short-distance or low-power applications, such as ferries, tugs, or barges.

Conclusion

Fuel efficiency is a crucial aspect of ship operation that affects both economic and environmental outcomes. Fuel efficiency can be improved by various technical and operational measures that optimize the design, performance, and management of the ship and its components. Fuel efficiency can also be improved by using alternative propulsion methods that reduce or replace the use of fossil fuels. These measures can help ship owners and operators achieve significant savings in fuel costs and emissions, as well as comply with the existing and upcoming regulations on energy efficiency and carbon intensity.

References

: IMO (2011). Amendments to MARPOL Annex VI – Regulations for the prevention of air pollution from ships. Resolution MEPC.203(62). https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/MEPC.203(62).pdf
: IMO (2021). Amendments to MARPOL Annex VI – Energy efficiency measures for ships. Resolution MEPC.329(75). https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/MEPC%2075%20RESOLUTIONS/MEPC%20329(75)%20-%20Amendments%20to%20MARPOL%20Annex%20VI%20-%20Energy%20efficiency%20measures%20for%20ships.pdf
: Wärtsilä (n.d.). Improving ship efficiency. https://c2e2.unepccc.org/kms_object/improving-ship-efficiency/
: IMO (2021). Amendments to MARPOL Annex VI – Carbon intensity reduction regulations for existing ships. Resolution MEPC.328(75). https://wwwcdn.imo.org/localresources/en/OurWork/Environment/Documents/MEPC%2075%20RESOLUTIONS/MEPC%20328(75)%20-%20Amendments%20to%20MARPOL%20Annex%20VI%20-%20Carbon%20intensity%20reduction%20regulations%20for%20existing%20ships.pdf
: Marine Insight (n.d.). 7 I need help with my dissertation Technologies To Reduce Fuel Consumption Of Ships. https://www.marineinsight.com/tech/7-technologies-to-reduce-fuel-consumption-of-ships/
: Solar Ship (n.d.). Solar Power for Ships: How Does It Work? https://solarship.com/solar-power-for-ships-how-does-it-work/
: Eco Marine Power (n.d.). Aquarius Marine Renewable Energy (MRE) System. https://www.ecomarinepower.com/en/aquarius-mre
: ABB (n.d.). Hybrid electric propulsion systems for ships. https://new.abb.com/marine/systems

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