Charting Cleaner Seas: How Energy Efficiency Could Save Shipping $220 Billion a Year

The World Bank's 2025 report "Keys to Energy-Efficient Shipping" delivers a clear and urgent message: the maritime industry holds in its hands one of the fastest and most cost-effective solutions to climate change, energy efficiency. Authored by Sophia Parker, Dominik Englert, Rico Salgmann, Simona Sulikova, and Maximilian Weidenhammer, the study is part of the World Bank's Mobility and Transport Connectivity Series and was developed with research support from CE Delft, UMAS at University College London, the Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping, Clarksons Research, and the International Council on Clean Transportation. Their collective findings reveal that efficiency alone could cut global shipping emissions by up to 40 percent by 2030, exceeding the International Maritime Organization (IMO)'s current ambition levels, and save the sector up to $220 billion annually by 2050.

The Hidden Power of Efficiency Over Fuel

While global debate around shipping decarbonization often focuses on alternative fuels such as ammonia, hydrogen, or methanol, the World Bank's analysis highlights that the world cannot wait for these solutions to mature. Energy efficiency, through both technical and operational improvements, offers immediate and proven results. Using CE Delft's advanced techno-economic "CE-Ship" model, the researchers assessed 30 measures across ship types and trade scenarios. Their results show that nearly half of all potential emissions savings, some 250 million tons of CO₂ per year, can be achieved at no additional cost, simply by implementing measures that repay themselves through lower fuel consumption.

The report argues that efficiency measures can act as the "missing link" in the maritime transition, cutting fuel demand in the short term and reducing the costs of adopting green fuels in the future. The potential for synergy between efficient ships and cleaner fuels forms the cornerstone of a sustainable shipping pathway.

Technologies That Deliver and Pay Back

Among the most promising interventions, speed optimization stands out as the simplest and most impactful. Reducing ship speeds by 10 to 30 percent can lower emissions by 5 to 15 percent across the global fleet. Complementary technologies like wind-assisted propulsion, air lubrication systems, propeller and hull optimization, and waste heat recovery can further amplify the benefits. The report notes that bulk carriers are particularly well suited to wind-assisted propulsion, while container ships benefit most from controlled speed reduction.

Although energy efficiency measures alone cannot achieve full decarbonization by 2050, they are indispensable in easing the global fleet's transition toward green fuels. As low-carbon fuels remain two to three times more expensive than conventional ones, improving efficiency now can drastically reduce the amount of fuel required later, cutting both emissions and operating costs.

Billions in Savings at Sea

Economically, the gains are transformative. The report estimates that investing $35 billion annually in fleet-wide energy efficiency upgrades could yield as much as $270 billion in yearly savings from reduced fuel consumption. By using less energy overall, the industry can lower its exposure to volatile fuel markets and lessen the financial burden of the green transition. The analysis also shows that efficiency improvements will be particularly critical for developing economies, where shipping costs directly affect trade competitiveness and food security.

For shipowners and operators, the message is equally clear: investing in efficiency is not only good for the planet, it's good business. A more efficient fleet is more resilient, more compliant with emerging regulations, and better positioned to thrive in a low-carbon future.

Barriers That Keep Ships Stuck

Despite clear economic logic, efficiency uptake remains disappointingly slow. The report identifies economic, behavioral, and organizational barriers as major obstacles. Split incentives between shipowners and charterers, limited access to capital for retrofits, and a lack of trustworthy data all contribute to the inertia. Technologies such as port call optimization (PCO) and wind-assisted propulsion, proven to deliver substantial fuel and emissions savings, remain underused due to fragmented governance and digital disconnects between ports and vessels.

The World Bank spotlights Just-in-Time (JIT) arrival systems as a critical solution to reduce port congestion and unnecessary fuel burn. Case studies like the Blue Visby Solution, supported by the Mærsk Mc-Kinney Møller Center and global partners, demonstrate that synchronized digital arrivals can cut fuel use immediately without major infrastructure changes. However, widespread adoption will require shared standards and stronger incentives.

Turning Efficiency Into Policy and Profit

The report outlines a comprehensive roadmap for action. Policymakers are urged to strengthen global performance standards such as the EEDI and CII while exploring complementary tools like emissions levies or targeted subsidies. Industry stakeholders should develop shared information standards and launch verified demonstration projects to boost investor confidence. Ports and local authorities must integrate digital data systems, share best practices, and adopt IMO and International Hydrographic Organization standards to ensure smooth, real-time coordination between ships and terminals.

Crucially, financial institutions have a pivotal role to play. By linking loan conditions to measurable performance metrics, they can reward energy-efficient vessels and de-risk retrofit investments. Development agencies can further accelerate progress by bundling smaller digital optimization projects with larger port infrastructure investments, ensuring that cost-effective but often overlooked efficiency measures are implemented at scale.

The Bridge to a Greener Horizon

The World Bank's research partners agree that energy efficiency is not an optional step in decarbonizing shipping, it is the foundation of the entire transition. While green fuels will ultimately define the sector's long-term future, efficiency improvements offer the fastest, fairest, and most financially sound route to substantial emissions cuts today. By aligning technology, policy, finance, and port operations, the maritime industry can turn sustainability from a cost into a competitive advantage. As the report states, "Energy efficiency is not merely an interim step, it is the cornerstone of a just and economically viable maritime transition."