Svitzer targets CO2 shipping with ATBs

Svitzer said the ATB concept could support CCS projects by reducing the need for onshore interim storage tanks.

Ms Skotting described the boundaries of Svitzer’s target market. She said CO2 transport was unlikely to settle on a single mode, and that this was where Svitzer expected to compete. “There’s going to be different solutions for transport that is suitable for different kinds of projects,” she said. “Sometimes a pipeline makes sense, sometimes a train makes sense.”

“We have developed in close collaboration with potential customers”

She placed Svitzer’s concept in the “short- to medium-distance shipping routes” category, which she described as the area where Svitzer could “compete with the big tankers, pipelines and land-based transport”. She also stressed that the unit was not, ‘an inland river barge’. “It is a coastal transport mode,” she explained.

Svitzer’s pitch is not that an ATB would become the default CO2 transport solution, but that it could offer CCS project developers a way to match transport and interim storage to coastal routes, smaller ports and phased build-outs. The concept’s flexibility is reinforced through design characteristics. The tug-barge system is described as having “a low draught for access to ports with shallow water without requiring additional towage assistance”, with indicative dimensions of an overall length of 88 m with one tank and 130 m with two tanks, a beam of 28 m, a draught of less than 6 m and a sea speed of up to 12 knots, with capacity to store 3,850–7,800 m³ of liquefied CO2.

Ms Skotting linked key design decisions to customer engagement and an attempt to avoid over-engineering for trades Svitzer did not plan to serve. “We have developed in close collaboration with potential customers,” she said, adding that Svitzer had “explored a few things and ended up in medium pressure, which seems to be the general ask”. She said Svitzer had explored high pressure, but “it was too expensive”, while low pressure suited longer distances than envisaged.

The storage function also drove basic engineering choices around insulation and holding time. “It is heavily insulated,” Ms Skotting said. “We do not have a liquefaction plant on board.” She described a design approach that relied on insulation and sufficient pressure margins, rather than onboard reliquefaction. “Because of the insulation and the sufficient pressure margin, we can keep the cargo for at least three to four weeks before it needs to be vented or offloaded,” she said.

On CO2 quality and handling, Ms Skotting described an unresolved interface between terminals, projects and ship operations, with measurement and return-gas management still being discussed on a project basis. “We do not want to take on board contaminated CO2,” she said, adding that quality measurement was likely “both onboard” and “before it even enters the tanks”. She also said return-gas handling would vary between projects, depending on whether gas could be handled by terminal systems or needed to be recirculated into the vessel’s tanks.

"the coupler system and the width between units created an interface standard that allowed different tug sizes to work with different barges"

Safety and standardisation, Ms Skotting said, rested on importing established practices from adjacent industries and working early with classification, suppliers and customers on risk. She said the concept would follow established industry standards for safety and gas handling.

Svitzer said it had conducted an early risk assessment with the classification society, designers and potential customers to identify risks and actions that could be taken at an early stage. An approval in principle (AiP) had been granted by ABS.

For loading and unloading, Ms Skotting stressed the gap between standard equipment frameworks and the need for project-by-project engineering and procedures. “There are a lot of standards around marine loading operations,” she said, but added that the parties would still “need to do a detailed design, together with the port, on the operational procedures.”

The next stage, she said, centred on interface standardisation between tug and barge, coupled with flexibility in dimensions and tank sizes to fit individual projects. Ms Skotting described the tug-barge connection as the anchor point for standardisation. “The interface between tug and barge is the same for all tugs and all barges,” she said, arguing that the coupler system and the width between units created an interface standard that allowed different tug sizes to work with different barges.

She also described where she saw design flexibility. “Where we have wiggle room is … the dimensions,” she said, listing tank, tug and barge size as areas that could be adjusted. She said Svitzer had “two main designs right now”, with room to adjust dimensions and, over time, to consider larger barges.

On risk scenarios, she said safety was the central hazard case that shaped early-stage work. “Probably the worst-case risk is an uncontrolled leak from a barge,” she said, adding that Svitzer approached that with “known technology and known procedures”, adapted for CO2 cargo and personal protective equipment. She also referred to redundancy in cargo control systems and the involvement of experts from gas handling suppliers, SIGTTO and the classification society,  to ensure a “360 degree” view of the main risks and proven mitigations.

Ms Skotting also pointed to Svitzer’s operating footprint as a resilience factor. Asked about contingency if a tug failed, she said Svitzer already had “a sizeable operation on the water”, and that in an unforeseen event, “our harbour tugs would be able to tow the barge”.

The limiting factor for progress, Ms Skotting said, sat upstream of transport procurement. She said many CCS projects had not taken investment decisions on capture facilities and had not taken final decisions on where to geologically store the CO2.

Svitzer said it had developed a concept intended to be adapted through detailed design. Ms Skotting said demand would crystallise once capture and storage decisions moved towards final investment decision and contracting structures became clearer.

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