Cargo ships are notoriously dirty. A new bill aims to clean them up

The Clean Shipping Act, proposed this week in Congress, would curb CO2 pollution from shipping and accelerate the adoption of nascent technologies.

a large cargo ship piled high with colorful shipping containers sits off the coast of Long Beach
A cargo ship anchored off the coast of Long Beach, California (Allen J. Schaben/Los Angeles Times via Getty Images)
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A new bill in Congress aims to drastically clean up cargo ships entering U.S. ports, by reducing the air pollutants and greenhouse gases that spew from the vessels carrying phones, food, furniture and virtually everything people use every day.

Rep. Alan Lowenthal (D-Calif.) introduced the Clean Shipping Act this week, at a time when global shipping emissions are rising, fueled by growing consumer demand and ceaseless supply-chain disruptions. The proposed legislation is meant to accelerate the investment and innovation needed to shift tens of thousands of ocean-crossing vessels from highly polluting diesel fuels to zero-carbon alternatives.

We must face the fact that we are at a tipping point in the climate crisis,” he said in a statement. No emissions sources can go overlooked.”

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The Clean Shipping Act has two key provisions to curb emissions from ships doing business in U.S. ports. The first directs the U.S. Environmental Protection Agency (EPA) to set carbon-intensity standards for marine fuels, which would become progressively stricter over time. As of January 1, 2027, ships would have to use fuels with life-cycle CO2 reductions of 20 percent below the 2024 emissions baseline. By 2040, fuels would need to be 100 percent below the baseline.

The second provision asks EPA to set rules to eliminate emissions while ships are docked or anchored, with a deadline of January 1, 2030. Idling ship engines are significant sources of cancer-causing particulate matter and smog-forming nitrogen oxides, which can damage people’s lungs. 

Lowenthal and the bill’s co-sponsor, Rep. Nanette Barragán (D-Calif.), together represent the ports of Long Beach and Los Angeles, which are both heavily affected by dirty ship exhaust. The ports comprise the nation’s largest shipping hub, with more than 40 percent of containerized cargo imports passing through the complex every year. Last year, record ship congestion drove pollution spikes that California regulators said threatened the health of surrounding communities.

The people living around ports are working-class communities, are communities of color. So this really addresses the environmental justice aspect” of shipping, Antonio Santos, the federal climate policy director for Pacific Environment, told Canary Media.

Environmental groups like Pacific Environment and maritime-technology experts said they welcome the Clean Shipping Act, even as they acknowledge that there are significant hurdles ahead — both in terms of passing climate legislation in Congress and in achieving the bill’s targets for curbing shipping emissions.

This kind of legislation is absolutely what’s needed to move this [transition] forward,” said Jing Sun, a professor of marine engineering and naval architecture at the University of Michigan.

At the same time, she added, the global shipping industry is only just beginning to produce cleaner fuels — like hydrogen and ammonia made from renewable energy — and to develop the engines and power systems that will use such alternatives. Unlike ferries and inland vessels, which can more easily switch to batteries, ocean-crossing ships are particularly hard to decarbonize because they consume large amounts of fuel over long distances.

We still don’t have a replacement that meets the energy density of fossil fuels,” Sun said.

International shipping contributes nearly 3 percent of annual greenhouse gas emissions every year, though that could rise to 17 percent of the global total in 2050 if no further action is taken, according to a 2015 analysis.

The International Maritime Organization, the United Nations body that regulates the industry, aims to reduce shipping-related emissions to 50 percent below 2008 levels by 2050. But maritime experts say much sharper reductions are needed, and much more quickly, in order for cargo shipping to play its part in limiting global warming to 1.5 degrees Celsius.

Frustrated by the organization’s slow pace, individual governments, shipping companies such as Maersk and advocacy campaigns like Ship It Zero are pushing their own initiatives, in the hopes of steering the wider industry toward decarbonization. Two dozen countries, including the United States, recently agreed to establish green shipping corridors” where vessels can fill up on zero-emissions fuels at the start and end of their voyage. The Clydebank Declaration, announced late last year, calls for creating at least six green trade lanes on a pilot scale by 2025, and then adding more and longer routes.

In the European Union, officials are considering the FuelEU Maritime initiative as part of a broader policy effort to curb the region’s total greenhouse gas emissions by 55 percent by 2030. The maritime proposal would limit the carbon-intensity of fuels used on ships and require vessels in ports to cut their engines and plug into shoreside electricity supplies. 

The Clean Shipping Act is modeled on Europe’s approach, Santos said. It also builds off similar initiatives from the city councils of Long Beach and Los Angeles, which have both passed resolutions to reach 100 percent zero-emissions shipping by 2030

Existing statewide policies in California could likewise serve as inspiration for federal shipping regulations. In California, container, cruise and other types of ships are similarly required to use electricity or emission-control technologies once they’ve docked. Regulators are also evaluating how to reduce emissions from anchored vessels — the source of last year’s pollution spike.

Sun said the bill’s goal to eliminate in-port emissions by 2030 seems reasonable, given that more and more ships are using shoreside power supplies instead of idling their engines. But achieving the second target of reducing fuel’s carbon-intensity will require significant international collaboration between governments, researchers and shipping companies. After all, the giant cargo ships coming in and out of U.S. ports will still need to access the same cleaner fuels or technologies on other continents.

As a nation, the U.S. has to act; we cannot ask others to collaborate if we don’t have a plan,” Sun said. But if we only act locally, I don’t think we can achieve that goal.”

Maria Gallucci is a clean energy reporter at Canary Media, where she covers hard-to-decarbonize sectors and efforts to make the energy transition more affordable and equitable.