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EEXI vs. EEDI - Understanding Their Similarities & Differences

Writer's picture: AdminAdmin

Updated: Jan 1

The International Maritime Organization (IMO) has introduced two critical energy efficiency standards: the Energy Efficiency eXisting ship Index (EEXI) and the Energy Efficiency Design Index (EEDI). These standards are essential for reducing greenhouse gas emissions from ships. They are pivotal in shaping the maritime industry's future. For ship owners, operators, and stakeholders, grasping the nuances of EEXI and EEDI is crucial.


A cargo ship sails past a sustainable energy landscape, featuring wind turbines and solar panels, highlighting advancements in energy efficiency and emissions reduction.
A cargo ship sails past a sustainable energy landscape, featuring wind turbines and solar panels, highlighting advancements in energy efficiency and emissions reduction.

The EEXI targets existing ships, while the EEDI focuses on new vessels built after January 1, 2013. Both aim to enhance the energy efficiency of the global fleet. By establishing specific requirements and reduction factors, they support the IMO's goal of cutting GHG emissions by at least 40% by 2030. Understanding EEXI and EEDI, their calculation methods, compliance strategies, and future impacts is essential for sustainable shipping.


Adhering to EEXI and EEDI regulations is more than a regulatory duty; it's a chance for the maritime sector to embrace energy-efficient technologies. It involves optimizing ship designs and implementing operational measures to boost performance. By focusing on EEXI compliance and following EEDI regulations, ship owners and operators can fight climate change. They also benefit from lower fuel costs, reduced operating expenses, and enhanced market competitiveness.


Key Takeaways

  • EEXI and EEDI are crucial energy efficiency standards introduced by the IMO to reduce greenhouse gas emissions from ships.

  • EEXI applies to existing ships, while EEDI applies to new ships built on or after January 1, 2013.

  • These standards contribute to the IMO's goal of reducing GHG emissions by at least 40% by 2030 compared to 2008 levels.

  • Compliance with EEXI and EEDI presents opportunities for adopting energy-efficient technologies, optimizing ship designs, and implementing operational measures.

  • Investing in EEXI compliance and adhering to EEDI regulations can lead to reduced fuel consumption, lower operating costs, and improved competitiveness in the market.



A futuristic cargo ship sailing on clear blue waters, equipped with advanced wind turbines and solar panels, surrounded by thriving marine life, depicted in a vibrant and eco-friendly landscape, showcasing sustainable shipping practices with a backdrop of green coastal cities.
A futuristic passenger ship cruises through clear blue waters, featuring innovative green technology with solar panels and wind turbines integrated into its sleek design.

Introduction to EEXI and EEDI

The maritime industry is pivotal in global trade, with 90% of the world's commerce reliant on international shipping. Yet, its carbon emissions account for 2-3% of global emissions, projected to increase by 50-70% in the coming decades. To combat this, the International Maritime Organization (IMO) has implemented two pivotal measures: the Energy Efficiency Existing Ship Index (EEXI) and the Energy Efficiency Design Index (EEDI).


Defining EEXI and EEDI

EEXI and EEDI are technical indices that assess a ship's energy efficiency based on its design and operational data. EEXI applies to existing ships built before January 1, 2023, whereas EEDI targets new ships. The EEXI or EEDI value is compared to a benchmark, which varies by ship type and size.


EEXI regulations, introduced in 2020, aim for a 40% reduction in carbon emissions by 2030 and 70% by 2050. Existing ships above 400 GT must comply with these requirements by January 2023. In contrast, EEDI regulations seek a 10% reduction in carbon dioxide emissions for new ships, with further improvements from 2025.


Importance of Energy Efficiency in the Maritime Industry

Enhancing energy efficiency in the maritime sector is critical for reducing fuel consumption, lowering operating costs, and minimizing environmental impact. Ships emit pollutants like nitrogen oxides (20-30% of global emissions) and sulfurous gases (10% of ship emissions). Large cargo vessels emit over 5000 tonnes of sulfurous gases, compared to around 100 grams of CO2 emitted by a petrol or diesel car.


Adherence to EEXI and EEDI guidelines fosters green shipping practices and maritime sustainability. Ship operators are motivated to invest in fuel-efficient solutions and reduce carbon footprints. These solutions include retrofitting energy-efficient technologies, operational power limitation, Engine Power Limitation (EPL), and switching to lower carbon fuels.


A 3D artistic impression of a futuristic ship equipped with the latest emission reducing techonologies
A cargo ship navigates through serene waters, surrounded by wind turbines under a bright sky, while digital interfaces hover above, symbolizing the integration of technology and sustainable energy in modern maritime transport.

EEXI: Energy Efficiency Existing Ship Index

The Energy Efficiency Existing Ship Index (EEXI) is a pivotal regulation aimed at enhancing the energy efficiency of existing ships. It seeks to diminish carbon emissions in the maritime sector. As part of the International Maritime Organization's (IMO) short-term measures, the EEXI regulation entered into force on January 1, 2023. It applies to all ships engaged in international navigation with a total tonnage of 400 tons or more.


Purpose and Scope of EEXI

The primary objective of the EEXI is to establish a standardized framework for assessing and enhancing the energy efficiency of existing ships. It sets performance benchmarks based on ship type, cargo capacity, and propulsion method. This encourages ship owners to adopt technical and operational measures that reduce fuel consumption and greenhouse gas emissions.


EEXI Calculation Methodology

The eexi calculation methodology considers various factors. These include the ship's engine and auxiliary engine power, transport capacity, reference speed, and emissions. The attained EEXI is determined by dividing CO2 emissions by transport work. This work is the product of the ship's capacity and speed. The calculation typically uses 75% of the Maximum Continuous Rating (MCR), rather than the maximum engine power.


Factor

Description

Engine Power

Main engine and auxiliary engine power

Transport Capacity

Cargo capacity and deadweight tonnage

Reference Speed

Speed at 75% MCR

Emissions

Specific fuel oil consumption and fuel mass conversion to CO2 mass


EEXI Compliance Requirements and Timeline

To comply with the eexi implementation timeline, ship owners must calculate and obtain approval for the attained EEXI by their initial annual, intermediate, or renewal International Air Pollution Prevention (IAPP) survey in 2023. The attained EEXI is then compared against the required EEXI value. This value is determined based on fleet statistics per ship type, cargo capacity, and propulsion method.


Ships that meet the required EEXI receive an International Energy Efficiency Certificate (IEEC). Non-compliant vessels may need to implement eexi technical measures such as Engine Power Limitation (EPL), Shaft Power Limitation (SHaPoLi), or other retrofitting solutions. These measures are to reduce emissions and achieve compliance. EEXI certification is essential for ships to continue legal trading and avoid penalties.


Classification Societies offer EEXI services to aid ship owners in conducting assessments, gaining approval for technical files, implementing energy efficiency measures, and ensuring regulatory compliance.

EEDI: Energy Efficiency Design Index

The Energy Efficiency Design Index (EEDI) is a pivotal measure aimed at enhancing energy-efficient ship designs and curtailing greenhouse gas emissions in the maritime sector. Introduced by the International Maritime Organization (IMO), the EEDI mandates new ships built from January 1, 2013, with a gross tonnage exceeding 400.


Purpose and Scope of EEDI

The EEDI's primary objective is to establish a minimum energy efficiency benchmark for new vessels, encouraging the integration of more efficient technologies and design elements. By incrementally raising standards over time, the EEDI seeks to significantly reduce the carbon footprint of the shipping industry.


EEDI Calculation Methodology

The EEDI calculation formula considers the ship's capacity, power, speed, and fuel consumption. Key factors influencing a ship's EEDI value include:

  • Specific fuel consumption of engines

  • Type of fuel used

  • Ship's speed

  • Deadweight of the vessel

  • Innovative mechanical energy-efficient technology used


The EEDI calculation adheres to MEPC.308(73) guidelines. The EEDI technical file is essential for each ship under Marpol Annex VI, providing the necessary parameters for determining the EEDI value.


EEDI Phases and Reduction Factors

The EEDI's implementation unfolds in phases, each demanding a more stringent reduction factor than the previous one. The reduction factors of carbon intensity are contingent upon the ship type and size, as illustrated in the table below:


Ship Type

Size

Phase 1


(1 Jan 2015 - 31 Dec 2019)

Phase 2


(1 Jan 2020 - 31 Dec 2024)

Phase 3


(1 Jan 2025 onwards)

Bulk Carrier

20,000 DWT and above

10%

20%

30%

Gas Carrier

10,000 DWT and above

10%

20%

30%

Tanker

20,000 DWT and above

10%

20%

30%

Container Ship

10,000 DWT and above

10%

20%

30%

General Cargo Ship

3,000 DWT and above

10%

15%

30%


For vessels constructed today, the EEDI value must be 10% less than the reference line value under phase 1 regulations. As the phases advance, the reduction factors escalate, compelling the industry towards more energy-efficient ship designs and the adoption of innovative technologies to fulfill the EEDI mandates.


The EEDI is a non-prescriptive, performance-based mechanism that leaves the choice of technologies to use in a specific ship design to the industry. As long as the required energy efficiency level is attained, ship designers and builders are free to use the most cost-efficient solutions for the ship to comply with the regulations.

By implementing the EEDI, the maritime industry is making substantial strides towards reducing its environmental footprint and contributing to global climate change mitigation efforts. As the EEDI phases evolve and new technologies emerge, we anticipate seeing increasingly energy-efficient and sustainable ship designs in the future.


Similarities between EEXI and EEDI

The Energy Efficiency Existing Ship Index (EEXI) and the Energy Efficiency Design Index (EEDI) are pivotal in the maritime sector. They aim to diminish greenhouse gas emissions from shipping. EEXI targets existing ships, whereas EEDI focuses on new constructions. Both indices strive to elevate vessel energy efficiency, supporting the International Maritime Organization's (IMO) goal. This goal is to cut carbon intensity by 40% by 2030 and 70% by 2050, relative to 2008 levels.


Shared goal of improving energy efficiency

EEXI and EEDI collaborate to enhance maritime energy efficiency. The shipping industry is responsible for 2-3% of global carbon emissions. These standards are essential in reducing the environmental footprint of vessels. They establish energy efficiency benchmarks, promoting the use of cleaner technologies and operational enhancements.


Use of similar calculation parameters

EEXI and EEDI employ analogous calculation parameters to gauge a ship's energy efficiency. They consider the vessel's capacity, power, and speed. This ensures a fair evaluation of energy performance across the industry.






A modern cargo ship sails through the ocean, embodying sustainability with surrounding wind turbines and solar panel icons.
A modern cargo ship sails through the ocean, embodying sustainability with surrounding wind turbines and solar panel icons.

The calculation for EEXI and EEDI involves a formula assessing carbon emissions per unit weight and distance. This standardized method enables ship owners to pinpoint areas for improvement. It guides them in making strategic decisions about retrofitting or operational adjustments to meet the standards.


Key differences between EEXI and EEDI

Both EEXI and EEDI aim to enhance energy efficiency in the maritime sector. Yet, they differ significantly. It is essential for ship owners, operators, and designers to grasp these distinctions. This knowledge ensures compliance and optimizes vessel performance.


Applicability to existing ships vs. new ships

EEXI and EEDI diverge in their application scope. EEXI targets all ships constructed prior to January 1, 2023. Its requirements adjust based on ship type and size, spanning from 250 to 10,000 DWT. In contrast, EEDI is geared towards new ships, setting efficiency benchmarks for their design.


Consideration of operational factors in EEXI

EEXI and EEDI differ notably in their consideration of operational factors. EEXI incorporates both technical design elements and operational aspects, such as engine power limitation (EPL) and overridable power reserve. This comprehensive approach evaluates a ship's energy efficiency under real-world conditions. EEDI, conversely, focuses solely on design, excluding operational variables.


Stringency of required reduction factors

The required reduction factors' stringency varies between EEXI and EEDI. EEXI imposes more stringent requirements, contingent on ship type and size. This disparity is evident when comparing Phase 1 ships (2013–2015) with stricter EEDI regulations. Most of these vessels already meet Phase 3 standards (>2025).


Standard

Applicability

Factors Considered

Reduction Stringency

EEXI

Existing ships (built before 2023)

Technical design and operational factors

More stringent, varies by ship type and size

EEDI

New ships

Ship design only

Phased approach


For existing ships, the EEXI calculation typically uses a lower main engine power input. This makes it easier for them to fulfill the requirements. This difference in calculation methodology underscores the distinct nature of EEXI and EEDI.


Compliance strategies for EEXI and EEDI

To meet the IMO's ambitious targets for reducing greenhouse gas (GHG) emissions in the maritime industry, ship owners and operators must adopt effective eexi compliance strategies and eedi compliance strategies. These strategies involve a combination of technical modifications, design optimizations, and operational measures to improve energy efficiency and reduce carbon intensity.


Technical modifications for EEXI compliance

For existing ships, technical modifications are crucial for achieving EEXI compliance. These modifications may include:

  • Engine power limitation (EPL)

  • Propeller optimization

  • Installation of energy-efficient technologies, such as waste heat recovery systems


By implementing these technical modifications, ship owners can improve the energy efficiency of their vessels and meet the required EEXI values.


Design optimizations for EEDI compliance

New ships must comply with the Energy Efficiency Design Index (EEDI), which assesses the vessel's CO2 emissions per capacity mile. To achieve EEDI compliance, ship designers can incorporate various design optimizations, such as:

  • Hull form optimization for reduced resistance

  • Use of lighter materials to reduce ship weight

  • Incorporation of wind-assisted propulsion technologies


These design optimizations can significantly enhance the ship's energy efficiency and ensure compliance with the progressively stringent EEDI phases.


Operational measures to improve energy efficiency

In addition to technical modifications and design optimizations, operational measures play a vital role in improving a ship's energy efficiency. Some effective operational measures include:

  • Voyage optimization for efficient route planning

  • Speed reduction to minimize fuel consumption

  • Regular hull and propeller cleaning to maintain optimal performance


By adopting these operational measures, ship operators can further reduce their vessels' carbon intensity and contribute to the industry's overall GHG emission reduction goals.


Compliance Strategy

EEXI

EEDI

Technical modifications

Engine power limitation, propeller optimization, energy-efficient technologies

Not applicable (for existing ships)

Design optimizations

Not applicable (for new ships)

Hull form optimization, lighter materials, wind-assisted propulsion

Operational measures

Voyage optimization, speed reduction, regular hull and propeller cleaning

Voyage optimization, speed reduction, regular hull and propeller cleaning


The maritime industry must embrace a holistic approach to energy efficiency, combining technical modifications, design optimizations, and operational measures to achieve EEXI and EEDI compliance and contribute to the global fight against climate change.

Impact of EEXI and EEDI on the maritime industry

The maritime industry has undergone significant transformations with the advent of the Energy Efficiency Existing Ship Index (EEXI) and the Energy Efficiency Design Index (EEDI). These regulations are pivotal in reducing greenhouse gas emissions, encouraging the adoption of energy-efficient technologies, and promoting sustainable practices. The influence of EEXI and EEDI extends to ship design, operations, and the sustainability of the shipping sector.


Incentives for Adopting Energy-Efficient Technologies

The implementation of EEXI and EEDI has created substantial incentives for ship owners and operators to invest in energy-efficient technologies. By enhancing the energy efficiency of their vessels, companies can significantly reduce fuel consumption and lower operating costs.


A state-of-the-art cargo ship navigates tranquil seas, equipped with advanced energy monitoring systems displaying real-time efficiency and performance metrics.
A state-of-the-art cargo ship navigates tranquil seas, equipped with advanced energy monitoring systems displaying real-time efficiency and performance metrics.

This environmental benefit also confers a competitive advantage in the market. Adopted energy-efficient technologies include:

  • Optimized hull designs for improved hydrodynamics

  • Advanced propulsion systems, such as air lubrication and waste heat recovery

  • Fuel-saving devices like Flettner rotors and wind-assisted propulsion

  • Efficient voyage planning and weather routing software


Challenges and Costs of Compliance

While EEXI and EEDI incentivize energy efficiency, compliance poses challenges for the maritime industry. Ship owners face financial hurdles in retrofitting vessels with clean technologies, a concern amplified for older ships. The costs of compliance vary based on the specific measures required for each vessel and the availability of cost-effective solutions.


Another challenge is the potential operational impact. Implementing energy-efficient technologies and practices necessitates changes in vessel speed, routing, and cargo handling procedures. The propulsion power, and thus CO2 emissions, of vessels is approximately proportional to the cube of speed, meaning a 20% reduction in speed can result in a 50% drop in emitted CO2. Balancing operational efficiency with compliance requirements is a delicate task for ship operators.


Further, the uncertainty surrounding future regulations and market conditions has led to hesitation among charterers in making long-term agreements. This increases pressure on ship owners to decrease freight rates and adapt to the evolving regulatory landscape.


Despite these challenges, the maritime industry recognizes the importance of reducing its environmental impact and is actively working towards compliance with EEXI and EEDI standards. By embracing energy-efficient technologies and practices, the industry can contribute to a more sustainable future while remaining competitive in the global market.


Future developments in maritime energy efficiency regulations

The maritime sector is intensifying its focus on decarbonization, with significant regulatory advancements expected. The International Maritime Organization (IMO) has set a goal to cut the carbon intensity of global shipping by 40% by 2030, relative to 2008 levels. To meet these targets, the IMO has mandated the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator. These measures require ships to assess their energy efficiency and establish yearly carbon intensity ratings.


Potential revisions to EEXI and EEDI requirements

The IMO is scheduled to assess the efficacy of EEXI and EEDI by January 1, 2026, potentially leading to stricter standards. These updates might include more aggressive reduction targets or the inclusion of additional ship categories. The EEXI compares a ship's energy efficiency against a baseline, mandating its calculation for vessels of 400 gross tonnage and above. The CII (Carbon Intensity Indicator), applicable to ships of 5,000 gross tonnage and above, will rate ships from A (best) to E (worst).


Industry bodies, like Intercargo and INTERTANKO, have voiced concerns over the CII rating formula, citing issues with routing and waiting times. BIMCO has introduced the CII Operations Clause for Time Charter Parties to navigate the commercial implications of the CII regulation.


Emerging technologies and alternative fuels

The integration of emerging technologies and alternative fuels is pivotal for enhancing ship energy efficiency and reducing emissions. Key technologies include:

  • Wind-assisted propulsion

  • Air lubrication systems

  • Fuel cell systems


Alternative fuels, such as hydrogen, ammonia, and biofuels, are emerging as crucial for maritime decarbonization. Developing retrofitting technologies for existing vessels and transitioning to fuels like ammonia, bioLNG, and hydrogen is essential.


Technology/Fuel

Potential Impact

Wind-assisted propulsion

Reduced fuel consumption and emissions

Air lubrication systems

Improved hydrodynamic efficiency

Fuel cell systems

Zero-emission power generation

Hydrogen

Clean fuel with zero carbon emissions

Ammonia

High energy density and zero carbon emissions

Biofuels

Reduced carbon footprint compared to fossil fuels


The transition to EEDI/EEXI compliance and decarbonization will challenge all shipping industry sectors, necessitating collaboration and innovation from all stakeholders.


Conclusion

The maritime sector is a significant contributor to global CO2 emissions, with ships emitting an estimated 1,046 million tonnes of CO2. This accounts for about 3.3% of the world's total emissions. The International Maritime Organization (IMO) has introduced the Energy Efficiency Existing Ship Index (EEXI) and the Energy Efficiency Design Index (EEDI). These measures aim to reduce greenhouse gas emissions from shipping, promoting the use of energy-efficient technologies and practices.


The EEXI targets existing ships, mandating adherence to energy efficiency standards. In contrast, the EEDI focuses on new ships, encouraging the design and construction of vessels with enhanced energy efficiency.


Ship owners and operators must consider various strategies, including technical modifications and design optimizations, to enhance their vessels' energy efficiency and meet the required standards.


The introduction of EEXI and EEDI will profoundly influence the maritime industry, encouraging the adoption of energy-efficient technologies and alternative fuels. Yet, compliance with these regulations may pose challenges and costs for ship owners and operators. As the industry undergoes this transformation, cooperation among stakeholders is essential. This includes regulators, technology providers, and shipping companies working together to achieve the IMO's decarbonization objectives. Their collective efforts will be crucial in ensuring a sustainable maritime transport future.


FAQ

What are EEXI and EEDI?

EEXI (Energy Efficiency eXisting ship Index) and EEDI (Energy Efficiency Design Index) are measures by the International Maritime Organization (IMO) to cut greenhouse gas emissions from ships. EEXI targets existing ships, whereas EEDI focuses on new ships built after January 1, 2013.


Why are EEXI and EEDI important for the maritime industry?

These measures are vital for enhancing ship energy efficiency, reducing fuel use, and lowering operational costs. They also help in minimizing the environmental footprint of shipping. The goal is to reduce GHG emissions by at least 40% by 2030, compared to 2008 levels.


How are EEXI and EEDI calculated?

EEXI and EEDI are calculated through technical evaluations of a ship's energy efficiency. This includes its design and operational data. The attained EEXI or EEDI is then compared to a benchmark, which varies by ship type and size.


What are the compliance requirements for EEXI?

EEXI mandates all ships of 400 gross tonnage and above. To comply, ships might need technical upgrades, such as engine power limits or propeller optimizations. The deadline for EEXI compliance was January 1, 2023.


What are the compliance requirements for EEDI?

EEDI targets new ships built after January 1, 2013, with a gross tonnage of 400 and above. EEDI requirements are phased, with stricter reduction factors applied over time. This depends on the ship type and size.


What are the main differences between EEXI and EEDI?

The key difference lies in their application. EEXI is for existing ships, while EEDI is for new ones. EEXI considers both design and operational factors, whereas EEDI focuses only on design. The reduction factors for EEXI and EEDI also differ.


How can ship owners and operators comply with EEXI and EEDI standards?

Ship owners and operators can comply by implementing technical upgrades, design optimizations, or operational measures. Examples include engine power limits, propeller optimizations, or voyage optimizations. Regular hull and propeller cleaning can also help.


What are the potential challenges and costs associated with EEXI and EEDI compliance?

Meeting EEXI and EEDI standards may require significant investments in ship modifications. This could affect ship operations. The costs vary based on the specific measures needed and the availability of cost-effective solutions.


What are the future developments in maritime energy efficiency regulations?

The IMO will review EEXI and EEDI by January 1, 2026, potentially leading to updates. The integration of emerging technologies and alternative fuels is also crucial for further energy efficiency gains and emission reductions.


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