Ship boat

Reinventing what it means to be a zero-emission ship

The Our Ocean 2022 conference, held recently in Palau, brought together countries from around the world to discuss and commit to action to protect the ocean, a vital source of food, livelihoods and recreation. for a large part of humanity. A significant portion of the discussions focused on the ocean-climate nexus and the role of international shipping in maintaining the health of the global oceans.

The United States, European Union, Chile, Australia, Japan and others have made new commitments to accelerate the decarbonization of the shipping sector, in part by establishing new zero-emission shipping routes, or so-called “green corridors”. The first such Green Corridor partnership was launched in January and focuses on the route between the Port of Shanghai and the Port of Los Angeles.

As the Global Maritime Forum noted at the conference, decarbonizing shipping requires a “total shift in fuels and technologies” to power ocean-going ships, and zero-emissions ships must operate “at scale and on a commercial basis during this decade”. Green maritime corridors provide an opportunity to drive innovation and rapid adoption of zero-emission technologies and fuels that will lead to a cleaner and greener global maritime fleet.

This transition, while undoubtedly requiring significant investment, amounts to a renaissance of the shipping industry – an opportunity to reinvent and redefine shipping and its relationship not only with the climate and our health, but also with our oceans and marine biodiversity. A simple way to capture the intersectional benefits of clean shipping is to simply expand what we mean by “zero emissions” ships.

Currently, the concept of “zero emissions” ships refers to ships that are propelled in such a way as to eliminate the series of atmospheric pollutants resulting from the combustion of fossil fuels, including greenhouse gases as well as other harmful particulate pollutants. , such as nitrous oxide and black carbon. , which create smog and have significant health effects, especially in port cities.

However, so far the concept has not included another type of harmful emission from ships that significantly pollutes our marine environment: underwater noise emissions.

For whales, fish and many other forms of marine animals, sound is life. Marine animals use songs and other sounds to communicate, find mates, navigate, locate prey and avoid predators. Underwater noise from human activities drowns out these songs and sounds, directly interfering with the ability of marine animals to hear the sounds essential to their existence.

Large ocean-going ships are as loud as jets taking off, emitting around 190 decibels of noise or more once underway. When you multiply that by the 100,000 ships that make up today’s global commercial fleet, it’s not hard to see how commercial shipping has become the main source of human noise pollution in the ocean. This cumulative noise has, in many areas, degraded the natural ocean habitats in which whales and other long-lived marine mammals have evolved beyond recognition. Several critically endangered whale species, such as the iconic southern resident killer whales in the Pacific Northwest and the North Atlantic right whales off the Atlantic coast, will not be able to recover unless harmful noise pollution of the oceans is reduced.

Trends in ship noise pollution are discouraging. The sound of the ocean has been doubling every decade since 1950, driven by the continued expansion of the world’s maritime fleet. However, the good news about underwater noise pollution is that, unlike many other forms of persistent pollution, it disappears as soon as the noise source is turned off.

So how do you “turn off” ship noise emissions? Although it is unlikely that we will ever be able to completely eliminate underwater noise from ships, it can be significantly reduced through innovative ship designs and technologies. Most underwater noise from a ship while underway comes from the propeller. A ship’s work of propulsion creates thundering amounts of noise due to a phenomenon called propeller cavitation. Cavitation can be reduced by design modifications and the use of various propeller technologies, such as “fin caps”, which were originally designed to improve fuel efficiency.

While there are overlaps in some technologies – like the “fin hoods” mentioned above or wind-assisted propulsion – that can both reduce noise and greenhouse gas emissions, it The zero-emission vessels we are working on are unlikely to be significantly quieter. business as usual, unless we proactively commit to designing and building ships that are both quiet and carbon-free.

The company has a unique window of opportunity – the next five to ten years – to transform international shipping. This transformation will require nothing less than a total change in the technologies (and fuels) that power ships. It would be a travesty for this renaissance in ship design to give up the possibility of tackling the noise pollution emitted by ships. If carbon emissions and underwater noise emissions are not addressed in parallel, there is a real risk that zero-emission ships criss-crossing the world in 2050 will continue to pollute the ocean with high levels of underwater noise. marine, simply leading to the displacement of pollution. burden.

We can successfully design and build ships that are both quiet and carbon-free, but we have to be intentional about that. In order to provoke such intentionality, it is imperative to expand our notion of zero-emission ships to include underwater noise emissions.

Linking the reduction of greenhouse gas emissions and noise emissions also makes sense in the short term. For example, slowing the speed of the vessel can improve fuel efficiency and reduce airborne and underwater noise. In a victory for the whales, slowing ship speeds can also significantly reduce the likelihood of a ship colliding with whales and killing them. The Protecting Blue Whales and Blue Skies initiative, which asks ships transiting parts of the California coast to slow to 10 knots, found that in 2020 participating ships contributed to a reduction of more than 24,000 tons of greenhouse gas emissions, 748 tons of NOx, and four decibels of ship noise in the region, while reducing the risk of ship-whale collision by 35%. Reducing whale mortality has its own climate benefits. Whales store large amounts of carbon in their bodies – each large whale is thought to sequester the equivalent of thousands of trees – and over their lifetime they play an important role in removing carbon from the atmosphere and sequestering it in their bodies when they die.

Other win-win solutions also exist. Shore-based electrical power, which powers a ship at berth so it can shut down its main engines, reduces both emissions and underwater noise when ships are berthed. Better voyage planning and just-in-time arrival programs can reduce congestion, air pollution and the need for ships to run noisy generators while waiting their turn in port. These actions have important co-benefits: they can significantly reduce harmful particulate air pollution that is responsible for localized pollution in port communities, many of which are already overburdened and suffer from long-standing health impacts.

As partnerships around the creation of green corridors proliferate – as they should – we encourage all stakeholders to consider not just how to decarbonise ships, but how to truly green shipping.

Earth Day gives us the opportunity to reflect on what is needed to ensure a healthy future, not just for ourselves, but for the myriad species with whom we share our blue planet. Reinventing the future of shipping to be free of all harmful emissions, including shipping-induced underwater noise, is a key step towards a healthier planet for all.

Originally posted on the NRDC Expert Blog. By Regan Nelson

Voluntary speed reduction zones near the ports of Los Angeles and Long Beach have been implemented to reduce the impacts of whale strikes. Image courtesy of NOAA.




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