Maritime transport has withstood the test of time to move large volumes of goods over long distances efficiently and cheaply. But it has also attracted criticism for its environmental impact – shipping is responsible for 3% of global greenhouse gas (GHG) emissions, which, according to the International Council on Clean Transportation, accounts for more than 1bn tonnes of CO₂ annually.

Furthermore, even as vessels modernise and become operationally more efficient, the surge in global consumption ensures that demand for shipping grows. Consider this: shipping transports 10bn t/y of goods, dwarfing the volume conveyed by air almost 300 times. Without intervention, shipping’s share of global emissions could grow to 17–18% by 2050, forecasts a European Environmental Agency report.

While many segments within the transportation ecosystem are making leaps towards sustainability – marked by a 35% annual growth in electric car sales and large companies adopting electric fleets – the global shipping industry remains a characteristically hard-to-abate sector.

Maritime decarbonisation 
Typically, the industry has enormous energy requirements for transporting large volumes of cargo over long distances and has razor thin margins. The long distances of many trans-ocean routes rule out electrification. Two categories of technologies such as efficiency improvements (eg voyage optimisation software, slow-steaming, advanced hulls and propellers) and wind propulsion systems (eg flettner rotors, vertical aerofoils, kites) can make marginal improvements.

Notable interest has been centred on the potential of green fuels to replace the dirty bunker fuels, but they are currently expensive and not ready for wide-scale deployment. Green fuels such as hydrogen, ammonia and methanol are estimated to be 10–20 years away from being in reliable, cost-effective supply. For instance, ammonia has recently gained attention as a potential zero carbon fuel, but will take time to be implemented if proven feasible. DNV GL predicts that widespread adoption of ammonia fuel will begin in 2037 and is expected to make up 25% of the maritime fuel mix by 2050.

At the same time, maritime assets have long lifespans – typically 25 years. The existing global fleet of ~100,000 ships are costly and difficult to retrofit to accept alternative fuels.

Despite these challenges, international regulations and market dynamics are compelling the industry to take immediate action. The International Maritime Organization (IMO) has introduced measures to reduce GHG emissions, targeting near net zero emissions by 2050. Prominent shipping customers, including retail giants like Amazon and Walmart, are exerting pressure on shipowners to provide low-carbon alternatives to meet sustainability goals across supply chains.

Given these shifts, the pivotal question emerges – as we navigate towards a net zero 2050, what immediate actions can ship owners take, especially when many of the green tech solutions remain in early phases of testing?

Onboard carbon capture 
Although carbon capture technology has been applied to stationary emissions sources, such as industrial facilities, its application to mobile emitters, including ships, is new but gaining momentum.

Seabound’s innovation involves a carbon capture device that attaches to a ship’s exhaust, capturing up to 95% of CO₂ emissions. The ship’s exhaust flows through a reactor full of pebbles made of calcium oxide – otherwise known as quicklime. A mineralisation process takes place where CO₂ binds to the pebbles to form limestone. The cleaner fumes are released from an outlet pipe. The limestone is temporarily stored onboard and replaced with fresh calcium oxide pebbles when the ship docks.

The application of CCUS to mobile emitters, including ships, is new but gaining momentum
Photo: Alisha Fredriksson

Testing the waters 
This summer, the Seabound team had the opportunity to pilot its onboard carbon capture (OCC) device on a container ship with Lomar Shipping. The equipment was transported from Seabound’s London R&D facility to the Yalova Shipyard in north-western Turkey, where it was installed on a vessel capable of carrying 3,200 containers. Seabound’s OCC device was tested while the ship conducted one of its usual shipping routes from India to the Gulf countries.

The pilot device is designed to capture 1.5 t/d of CO₂. The final tests are ongoing. Initial tests show promising carbon capture rates, as well as potential to capture other harmful gases released from the burning of the ship’s dirty bunker fuels, such as sulphur.

This pilot comes at a moment of increased interest in OCC in the maritime sector. For example, last year the European Union (EU) granted €3.4mn for an international collaboration to demonstrate carbon capture onboard two LNG-fuelled ships. A key focus is to study the gaps in developing full-chain carbon capture, use and storage (CCUS) networks, including linking OCC with transport networks and storage sites. This is significant, as one of the biggest challenges in carbon capture generally is the insufficiency of transportation and storage infrastructure.

Seabound will leverage the insights gained from this initial pilot to begin an R&D phase. This will involve developing a larger, optimised version of the OCC device for commercial use. The goal is to test the new device on a ship towards the end of 2024 and gear up for commercial deployment in late 2025 or early 2026.

Seabound has ambitions to install the devices on 1,000 ships by 2030 and 10,000 ships by 2040. The 2040 goal would enable Seabound to capture 200mn t/y of CO₂ by 2040. The short-term focus will be on developing devices for cargo ships, with potential to diversify to other vessels in the future.

A consumer poll by Yale University, George Mason University and Climate Nexus found that 74% of consumers would be more likely to shop at companies that use cleaner ways to ship their goods. Overall, 84% of consumers thought that the shipping industry should be doing more to reduce the environmental impacts of shipping goods around the world.

Challenges  
For Seabound, the need to store limestone onboard between ports, effectively utilising cargo space, is a challenge. Other companies have deployed OCC, and those leveraging amine-based solutions, for example, face the dilemma of storing liquid CO₂ in tanks onboard.

Moreover, OCC devices need to be tailored to the unique design of each ship or ship-type, eliminating the potential for a ‘one-size-fits-all’ approach due to diverse ship architectures.

Timing is everything 
Despite the complexity and uncertainty of decarbonisation in shipping, many factors are aligning to accelerate emissions reductions and drive innovation.

One of the greatest driving forces of decarbonisation is enabling international and regional policy. Starting this year, the IMO has mandated shipowners to report their energy efficiency onboard and annually report their emissions. The EU has also announced that shipowners with large vessels (of 5,000 gross tonnage and above) travelling within the EU or to EU ports will be subject to the EU Emissions Trading Scheme (ETS), starting next year.

This means that shipowners will need to either reduce their emissions, or they will need to purchase allowances for each tonne of CO₂ emitted. The EU will allow shipowners to use carbon capture to consider emissions as ‘not emitted’ under the ETS framework. The price of allowances in the EU has been increasing steadily, reaching an all-time peak of €105/t in February 2023. This price tag on pollution will likely drive shipowner behaviour and drive demand for low-carbon solutions.

There has also been a surge in international interest in establishing green shipping corridors following the signing of the Clydebank Declaration at COP26 in 2021. The initiative is designed to advance the IMO’s sustainable shipping targets. The signatories, including the UK, US, Germany and France, have committed to establish six ‘green corridors’ by 2025 – entirely decarbonised maritime routes (including land-side infrastructure and vessels) between two or more ports – to accelerate the development of zero-emission fuels, low-carbon enabling infrastructure and effective legislation and regulation. Announced corridors include Shanghai-Los Angeles and Antwerp-Montreal.

In addition to these top-down measures, shipping customers are increasingly demanding shipowners and charterers to reduce their emissions. For example, Cargo Owners for Zero Emission Vessels (coZEV) is a platform specifically designed for climate-leading customers of the shipping industry where cargo owners can come together to undertake high impact initiatives that accelerate the transition to net zero maritime shipping. Companies such as IKEA, Unilever and Patagonia have signed their Declaration, committing to purchase only zero emissions ocean transportation services by 2040.

There’s also research to suggest that customers are willing to pay for the increased costs downstream. A consumer poll by Yale University, George Mason University and Climate Nexus found that 74% of consumers would be more likely to shop at companies that use cleaner ways to ship their goods. Overall, 84% of consumers thought that the shipping industry should be doing more to reduce the environmental impacts of shipping goods around the world.

Charting change 
As the maritime industry steers toward a more sustainable future, it is clear that the appetite for change and action is growing across the sector. While Seabound’s OCC represents just one facet of this broader transformation, the interest in adopting new solutions reflects the sector’s willingness to change.