How the U.S. Can Cut Maritime Emissions

New report analyzes approaches to decarbonize the U.S. fleet

For several years, Ocean Conservancy has joined with partners to sound the call for the decarbonization of the shipping industry. Each year, the shipping industry delivers more than 10 billion tons of goods—amounting to approximately 90% of all trade but emits 1 billion metric tons of carbon dioxide in the process. These pollutants are not only a major culprit of advancing climate change, but also impact air quality in marginalized port communities and cause approximately 250,000 premature deaths and 6 million childhood asthma cases around the world each year. 

The United States continues to affirm its commitment to decarbonizing the shipping industry—from signing the Clydebank Declaration, to developing green shipping corridors, to, most recently, releasing a new blueprint for transportation decarbonization. Eliminating shipping emissions will go a long way towards reaching a zero-carbon future. However, to achieve these ambitions the U.S. will need a clear navigational route. 

A new report from Ocean Conservancy and Energy and Environmental Research Associates, Reducing Greenhouse Gases in the Maritime Sector: Approaches for Decarbonizing the U.S. Fleet, explores options for how the United States can transition its U.S.-flagged vessels to a zero-carbon future and decarbonize the federal fleet. Building on an earlier analysis of The Maritime Fleet of the USA, this report analyzes vessel characteristics, fleet activity and alternative maritime fuels and technologies, and makes a series of policy recommendations. The report focuses on 153 of the 180 larger, privately owned U.S.-flagged commercial vessels and 30 research vessels owned and operated by U.S. federal agencies, also known as the federal fleet.

While shipping accounts for only 0.58% of emissions in the United States, decarbonizing domestic fleets is an important part of the United States. reaching its goal of a net-zero greenhouse gas economy by 2050. If the U.S. government and industry take the steps to be first movers with the commercial and federal fleet and build the appropriate infrastructure to support the transition to zero-emission alternative fuels and technologies, this will have a cascading effect of removing barriers for other fleets that call on U.S. ports from around the world to switch to these alternative fuels. Below we outline the various approaches and recommendations made by the report to achieve this goal.

An aging U.S. fleet

The U.S. commercial fleet is generally older, with more than half of its vessels more than 15 years old. These vessels use less efficient technologies that emit more greenhouse gases and pollution than those found in newer vessels, and many are nearing the end of their useful lives. Replacing these vessels would result in a higher impact on emissions reductions comparatively. The federal fleet is also facing a turning point, with estimates that it will decline to only 18 vessels by 2030 if no investments are made into retrofits and new builds. Strategies to keep existing vessels operating and reduce their emissions include retrofitting the vessels and integrating new technologies into their builds. The aging fleet is a problem, but it is also an opportunity for government and industry to invest in developing and testing new clean vessel designs and retrofit technologies that can support decarbonization globally. 

Fuels for the future

Alternative marine fuels and technologies, including ammonia, biofuels, hydrogen and methanol, are either in use or under consideration by the shipping industry to help it meet both the International Maritime Organization’s (IMO’s) carbon intensity standards and the Biden administration’s new commitment to decarbonize the sector by 2050. While each alternative fuel has costs and benefits, our report finds that green hydrogen and green ammonia, which are produced with 100% renewable energy, are the most promising options for a zero-emission future. Green hydrogen in fuel cells does not contain carbon or emit greenhouse gases or black carbon at any point in its lifecycle. The production of green hydrogen and ammonia, as well as all other zero-emission fuels, will take time to ramp up. In the meantime, lower carbon transition fuels that can facilitate production and infrastructure development—and that don’t lock us into continued fossil fuel dependence—should be considered, along with more investment in renewable energy, such as wind, to power the production of green fuels. 

Investing in infrastructure

Within the U.S.-flagged domestic and international commercial fleet, just 35 of the 153 vessels analyzed account for more than half of the total estimated annual energy consumption. The good news is that the top ten ports visited by these vessels all have the potential for alternative fuel bunkering. Similarly, only three vessels account for more than 20% of the energy consumption for the federal fleet. While existing alternative fuel infrastructure may be more limited at the top 10 ports the federal fleet visited, all of the ports are within 500 miles of hydrogen-production facilities. With hydrogen available to the top ten ports for both the U.S. commercial fleet and federal fleet, the United States could advance decarbonization by investing in renewable green energy infrastructure and hydrogen refueling facilities at these ports, and, in turn, create green shipping corridors all around the country.

Funding and financial incentives

The maritime industry has historically been slow to adopt new technologies that come at a cost premium, and other issues like regulatory uncertainty and limited availability of alternative fuels are further delaying progress. We need funding for technical research and development to ensure the availability of safe, efficient fuels and propulsion systems. Funding for clean and green energy grids is also important in producing alternative, zero-carbon fuels, like green hydrogen, without any lifecycle emissions. The Infrastructure Investment and Jobs Act and the Inflation Reduction Act provided historic levels of funding that can be used for shipping decarbonization. We need to push to ensure these funds and others are used for maximum emissions reductions, fuel and vessel development, and landside infrastructure, and call for more public and private investments. In addition, we also need to explore how to use tax and other incentives as mechanisms to push industry along, including regulation that reduces risks faced by first movers. Taking this two-pronged approach will give industry the means and reason to act quickly, a necessity for reaching sector-wide goals.

Looking forward

There is no better time for the United States to signal a commitment to an emissions-free future internationally than with an ambitious domestic shipping decarbonization plan. At the upcoming 80th Marine Environment Protection Committee meeting in July 2023, the IMO is set to revise the initial strategy to reduce greenhouse gas emissions from shipping which will govern the sector worldwide. Reducing Greenhouse Gases in the Maritime Sector: Approaches for Decarbonizing the U.S. Fleet explores the opportunities for decarbonizing the U.S. fleet and provides a comprehensive analysis of technical and policy approaches to achieve emissions reductions. We call on advocates and policy makers to join us in pursuing these opportunities and positioning the United States to be a leader in the race to decarbonization. 

Browse Topics
Our work is focused on solving some of the greatest threats facing our ocean today. We bring people, science and policy together to champion innovative solutions and fight for a sustainable ocean.
Read more
View Current Posts
Back to Top Up Arrow