New analysis by UC Berkeley highlights Japan’s port decarbonization leadership

A new study, “An Analysis of Japan’s Carbon Neutral Port Initiative and Yokohama Port and Harbor Decarbonization Plan,” from the University of California, Berkeley examines Japan's innovative approach to decarbonizing maritime ports. Japan’s Carbon Neutral Port (CNP) certification framework and the City of Yokohama’s port decarbonization initiatives represent serious and forward-looking efforts to address the complex challenge of maritime emissions reduction.

The study comes as momentum builds for decarbonization of the international shipping industry, despite recent delays at the International Maritime Organization (IMO). In a period of regulatory uncertainty and rapid technological change, the report underscores the importance of ensuring that certification systems and infrastructure plans continue to evolve in step with emerging fuel pathways, electrification needs and international policy developments.

The U.C. Berkeley analysis, commissioned by Pacific Environment and authored by David Wooley, director of the Environment Center at University of California’s Berkeley's Goldman School of Public Policy, examines Japan's Carbon Neutral Port (CNP) certification initiative and the Port of Yokohama's comprehensive decarbonization plan. The CNP certification, established by Japan's Ministry of Land, Infrastructure, Transport and Tourism in 2025, sets benchmarks for Japanese maritime terminals to reduce greenhouse gas emissions and improve air quality in port communities.

The City of Yokohama's Port and Harbor Decarbonization Plan, which won the 2025 IAPH Sustainability Award for Climate and Energy, includes 121 projects ranging from harbor craft electrification to next-generation low- and zero-carbon marine fuels. Notably, Yokohama is pioneering the use of "battery-tanker" ships that would transport power from floating offshore wind turbines to shore using vessels filled with batteries.

“Japan's CNP Certification is a very thoughtfully constructed program that will encourage and enable Japanese maritime terminals to reduce greenhouse gas emissions from port operations,” said David Wooley, Director of the Environment Center at University of California’s Berkeley's Goldman School of Public Policy. “In many ways Japan is ahead of other nations on decarbonization of maritime terminals and related industrial operations. The Port of Yokohama serves as a model for other port decarbonization efforts in Japan and will positively influence port decarbonization efforts internationally.”

Across Asia, ports are also advancing their own decarbonization strategies alongside Japan’s Carbon Neutral Port initiative. China has expanded shore power deployment at major ports under Ministry of Transport green port policies, Republic of Korea is scaling up Alternative Maritime Power (AMP) infrastructure under the Ministry of Oceans and Fisheries’ maritime decarbonization strategy, and Singapore’s Maritime and Port Authority (MPA) is implementing the Maritime Singapore Decarbonization Blueprint 2050, including electrification of harbor craft and development of supply chains for low- and zero-carbon marine fuels. These regional initiatives highlight the growing role of Asian ports in accelerating maritime decarbonization through electrification, alternative fuels and port infrastructure development.

"While the IMO delays action on global shipping emissions, Japan is demonstrating the kind of leadership the world needs," said Katsunori Hirano, Japan Climate Specialist at Pacific Environment. "With the launch of Japan's national CNP Certification and the implementation of the Port of Yokohama’s decarbonization plan, Japan is proving that ambitious climate action in the maritime port sector is both necessary and achievable. This report is intended to contribute constructively to this ongoing process. Drawing on the experience of California ports, the analysis identifies opportunities for refinement and coordination to support national and local authorities, as well as industry stakeholders, in strengthening implementation and maintaining Japan’s credibility and competitiveness in sustainable port development.”

Key recommendations for Japan's Carbon Neutral Port Initiative (CNP)

The analysis offers several recommendations to strengthen Japan's port decarbonization efforts:

• Shore Power Requirements: The CNP recommends but does not require shore power (to allow ships to plug into grid electricity while docked). Shore Power should be a mandatory requirement for higher level port ratings under the CNP. Shore power is increasingly being adopted by major ports worldwide.
• Electric Power Infrastructure Planning: The CNP could be strengthened by requiring enhanced planning for electric power infrastructure, needed to support growing demand from shore power, cargo handling equipment electrification and future battery-powered coastal shipping.
• Sustainable Biomass Supply Chains: Japan’s port decarbonization policy could be strengthened by development of domestic supply chains for sustainable biomass feedstocks needed to produce low- and zero-carbon liquid marine fuels (e.g., green methanol). Japan produces substantial amounts of agricultural and forestry residues that could be used to reduce emissions from vessels calling at Japanese ports.
• Methane Emissions: The CNP could expand port greenhouse gas inventories and control measures beyond carbon dioxide to include methane emissions. The analysis recommends that the CNP could take a more neutral position on liquefied natural gas (LNG) as a maritime fuel, given its significant lifecycle emissions and supply chain constraints.
• More Frequent Updates: Shortening the revision cycle of the certification system from five years to two or three years would enable the CNP to better reflect rapidly changing technologies and practices in maritime decarbonization.

Recommendations for Port of Yokohama

For the Port of Yokohama's decarbonization plan, the analysis recommends:

• Enhanced Electric Power Planning: Port decarbonization plans should ensure adequate electric power supply infrastructure is planned in parallel with electrification efforts, potentially requiring investment in microgrids, onsite renewable generation and stationary battery storage.
• Hydrogen Pipeline Details: It would be helpful to provide more detail in future plan iterations on the ambitious hydrogen distribution and storage system connecting the port with nearby chemical, refining, steel and power plant facilities.
• Alternative Fuel Development: Future decarbonization plans could include specific milestones to support Intercoastal fleet electrification and supply chains for zero-carbon maritime liquid fuels, including bio-methanol production from sustainable urban and rural biomass (as a cost-effective bridge to e-methanol).
• Expanded Boundaries for Port Emission Inventories: Yokohama could create a best practice for maritime port emission inventories by including emissions from ocean-going vessels traveling through the port area and hinterland trucking operations. This will provide a more complete picture of port-related emissions, similar to recent actions by California ports.
• LNG Incentives: Yokohama could consider phasing out port-call incentives for LNG-propelled ships. Instead, incentives could better be used for development of domestic supply chains for low or zero-carbon marine fuels.
• Air Quality Hot Spots: Short-range dispersion modeling can be used to identify air pollution hot spots in neighborhoods near the port and prioritize emission controls in those areas.

The analysis notes that maritime terminals play a critical role not only for trade but also for decarbonizing other industry sectors including refineries, steel, cement and manufacturing. Yokohama's comprehensive approach, which involves a network of 42 public-private partnerships, demonstrates the potential for local governments to lead the transition to net-zero port operations while creating economic opportunities and protecting public health.