Shipping lacks data to measure energy efficiency’s emissions savings, analysis finds

Drawing on the IMO’s Comprehensive Impact Assessment, the Center estimates that energy efficiency could contribute approximately 10% of modeled emissions reductions by 2030, increasing to 28% by 2040 and nearly 38% by 2050.

These figures reflect the contribution of efficiency measures within a modeled decarbonization pathway rather than verified reductions achieved by the existing fleet.

The analysis covers technical and operational measures, including hull and propeller improvements, waste heat recovery, air lubrication, speed optimization and more efficient voyage planning.

Lack of reliable data limits progress

According to the Center, one of the main obstacles to realizing energy efficiency’s potential is the absence of consistent information on how widely efficiency technologies and operational measures have been adopted across the global fleet.

While fuel consumption is recorded through established reporting mechanisms, there is no equivalent standardized requirement to document which energy efficiency technologies are installed, whether they are actively used or how effectively they perform.

The Center emphasizes that installing a technology does not necessarily guarantee energy savings. Actual performance depends on operating conditions, maintenance, crew competence and the extent to which the equipment is integrated into daily vessel operations.

Analysis of voluntarily reported data from Clarksons indicates that adoption varies significantly between different technologies and vessel segments. Hull and propeller improvements are among the most widely reported measures, while technologies such as waste heat recovery and air lubrication have considerably lower reported uptake.

However, MMMCZCS cautions that incomplete voluntary reporting makes it difficult to establish an accurate picture of fleet-wide implementation.

Operational and commercial barriers remain

Beyond data limitations, the publication identifies financial, operational and organizational barriers that can prevent shipowners and operators from implementing efficiency measures.

One challenge concerns the difficulty of verifying savings, as vessel performance is influenced by factors including weather, speed, cargo load and operating conditions. This complicates efforts to determine the contribution of individual technologies.

The Center also highlights the importance of crew training, operational follow-up and maintenance to ensure that installed equipment delivers its expected benefits throughout its service life.

Commercial arrangements can create additional obstacles. Under certain chartering agreements, shipowners bear the cost of installing efficiency technologies while charterers benefit from reduced fuel consumption, weakening incentives for investment.

Operational measures such as just-in-time arrival also require coordination between vessels, ports and other stakeholders, meaning that their implementation cannot always be controlled by shipowners alone. Although carbon pricing could improve the financial attractiveness of energy efficiency investments, the Center argues that economic incentives alone will not resolve these challenges.

Center calls for stronger SEEMP requirements

The publication identifies the IMO’s ongoing Phase 2 review of its Energy Efficiency Framework as an opportunity to improve how energy efficiency measures are documented and monitored.

In particular, the Center proposes strengthening the Ship Energy Efficiency Management Plan (SEEMP) to include more systematic information on the technologies and operational measures installed and used aboard vessels.

Existing IMO instruments, including the Data Collection System (DCS), Carbon Intensity Indicator (CII), Energy Efficiency Design Index (EEDI) and Energy Efficiency Existing Ships Index (EEXI), provide mechanisms for monitoring fuel consumption, carbon intensity and vessel efficiency.

However, according to the Center, these mechanisms do not consistently identify which specific efficiency measures are being implemented or whether they are operating as intended.

Strengthening SEEMP reporting could therefore improve transparency, support the assessment of technology adoption and provide regulators with a clearer understanding of the industry’s progress.

The Center also raises the possibility of consolidating this information into a centralized database, potentially allowing broader access to data on the uptake of energy efficiency measures.

These proposals remain recommendations rather than adopted IMO requirements.

Unlocking energy efficiency’s decarbonization potential

The Center emphasizes that energy efficiency remains an important component of shipping’s transition toward lower emissions, alongside the adoption of alternative fuels.

Research cited in the publication suggests that just-in-time arrivals could reduce annual shipping CO₂ emissions by 10–11%, while improved antifouling measures could offer savings of up to 19% of annual greenhouse gas emissions. These estimates concern different measures and should not be interpreted as directly additive.

However, realizing the wider potential of energy efficiency will require more than installing new equipment. The Center stresses the need for reliable performance data, consistent operational practices, effective training and regulatory frameworks that support implementation.

As the IMO continues reviewing its energy efficiency requirements, the findings highlight the importance of moving beyond technology adoption toward documenting actual use and assessing whether efficiency measures deliver the expected emissions reductions.