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EEDI, EEXI and CII: Improving Environmental Ratings with HeatPower

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EEDI, EEXI and CII: Improving Environmental Ratings with HeatPower

Total Views: 2308
March 10, 2024

Regulating the environmental impact of the shipping industry may be nothing new, but the introduction of new rules and the strengthening of existing measures is transforming the sector in a bid to accelerate decarbonization. Since the International Maritime Organisation’s (IMO) focus on energy efficiency in MARPOL Annex VI, there has been a flurry of environmental regulations, targets and limitations implemented from a variety of sources.

Minimizing Environmental Impact with Sustainable Technology

From the IMO’s GHG Strategy and its subsequent revisions to the EEDI, EEXI, CII and the expansion of the ETS to include the maritime sector, shipowners, operators and shipyards are under pressure to mitigate their environmental impact or face pecuniary sanctions and/or commercial disadvantages.

As a result, a vessel’s environmental impact is a top priority throughout its entire lifespan. From inception and design to route planning and operation, a ship’s GHG emissions must be curtailed at every stage to maximize the vessel’s value and comply with critical environmental and industry regulations.

Fortunately, the latest emissions-reduction technology can enable shipowners, operators and shipyards to meet the requirements of increasing environmental regulations and enhance the sustainability of their operations. Here, we explore how Climeon’s HeatPower 300 waste heat recovery system can boost key environmental ratings:

Energy Efficiency Design Index (EEDI)

Used to ensure new-build ships achieve a ‘minimum energy efficiency level per capacity mile’, the EEDI sets standards in the form of a Required EEDI rating, based on the type and size of the vessel. To achieve compliance, a vessel’s actual or ‘attained’ rating must be equal or better to its corresponding required rating.

As new phases of the EEDI have been introduced and requisite ratings strengthened, design houses and shipyards must ensure that today’s new-builds are as energy efficient as possible. In addition to achieving regulatory compliance, an enhanced EEDI rating can give vessels and shipowners a competitive advantage when it comes to securing future charters, thus impacting the ship’s value and subsequent ROI. 

Amongst the sustainable maritime technology being used to increase the energy efficiency of new-build ships is Climeon’s HeatPower 300 system. By repurposing on-board waste heat into clean electricity, the ship is less reliant on fuel-powered generators and, therefore, consumes less fuel. In turn, the vessel’s energy efficiency is increased, GHG emissions are reduced and improved EEDI ratings can be achieved.

To learn more about how HeatPower 300 is being used to accelerate maritime decarbonization, download our White Paper here.

Energy Efficiency Existing Ship Index (EEXI)

The EEXI measures the energy efficiency of existing vessels based on their technical design. Essentially, it is the equivalent of the EEDI for ships in operation and imposes retrospective energy efficiency requirements on active fleets.

Depending on the age of a vessel, it may have been designed and built at a time when environmental regulations were far more relaxed. If so, shipowners may need to make significant modifications to improve the energy efficiency of the vessel and secure an optimal EEXI rating.

Despite this, not all sustainable technology is viable for retrofit projects, either due to design and/or financial and practical constraints. With Climeon’s HeatPower 300 technology, however, shipowners can enhance the energy efficiency of existing vessels via accelerated integration, low payback periods and streamlined retrofit applications.

As HeatPower 300 is designed to maximize sustainable power output from waste heat at temperatures between 80 – 100° degrees, a single heat source, such as jacket cooling or HT water can be used to achieve a simplified and efficient installation. When multiple heat sources are available, these can also be incorporated to boost power outputs and maximize the availability of sustainable, on-board electricity. 

Carbon Intensity Indicator (CII)

The carbon intensity indicator determines a vessel’s energy efficiency by assessing ‘grams of CO2 emitted per cargo-carrying capacity and nautical mile’. Ships are subject to a ’required annual operational CII’ but 2024 is the first year that ‘attained annual operational CII’ verification will take place.

As CII thresholds will become more stringent, shipowners will be expected to make continuous improvements to improve the carbon intensity of ships. Furthermore, ships that receive low CII ratings will be required to update their SEEMP with a corrective action plan.

Crucially, Climeon’s HeatPower 300 system can assist shipowners in securing favorable CII ratings by cutting fuel consumption and reducing CO2 emissions. As the clean electricity produced by HeatPower 300 can be used to power a percentage of on-board operations, less fuel is required and fewer emissions are generated.

When a vessel’s annual fuel consumption and CO2 emissions factors are improved, the corresponding CII calculation and rating is also enhanced. As a result, ships can meet, or even exceed, CII requirements and secure higher ratings.

Achieving Environmental Compliance with Climeon’s HeatPower 300 System

A significant proportion of waste heat is generated on board any operational vessel and the majority of this waste heat is produced at relatively low temperatures. 

Designed by marine engineers to utilize this low-temp waste heat, Climeon’s HeatPower 300 technology is built for challenging on-board environments and simplified integration, which reduces payback periods and enhances ROI. This streamlines the integration process and ensures suitability for both new-build and retrofit applications.

With the potential to cut fuel consumption by 1300 mt/yr and reduce CO2 emissions by 100,000 mt over the course of a vessel’s lifespan, Climeon’s HeatPower 300 technology enables shipowners, operators and shipyards to meet environmental regulations, secure enhanced EEDI / EEXI and CII ratings and transition to a more sustainable future.To find out more, visit


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