Carbon Capture and Storage (CCS) only works if the captured CO2 can be reliably transported from the capture site to the geological storage location. For many CCS projects – particularly those at coastlines without pipeline connections – sea transport is the only economically viable option. From this, a standalone shipping segment emerges with specific vessel types, its own logistics chain, and dedicated infrastructure.
LCO2 carriers (Liquefied CO2 Carriers) are not modified gas tankers. Liquid CO2 has a unique phase diagram with a triple point at 5.2 bar and -56.6 °C. Below this pressure, CO2 sublimes directly – there is no liquid state. This means: tank design, pressure maintenance, and temperature management follow their own logic, fundamentally different from LNG, LPG, or ethylene.
The development resembles the early years of LNG transport in the 1960s: a new product requires new vessels, new port infrastructure, and new rules. The parallels are not only historically interesting – they also help assess the probable market development.
Several converging developments are driving the market for LCO2 carriers. The most important are the growing number of CCS projects, the regulatory framework, and the geological geography of storage sites.
CCS projects: Northern Lights in Norway is the best-known project but far from the only one. Porthos in the Netherlands, Greensand in Denmark, Acorn in Scotland, and several projects in Australia and Asia plan seaborne CO2 transport. The cumulative annual transport demand could grow to 50 to 100 million tonnes by 2035.
Regulatory drivers: The EU Taxonomy recognises CCS as a sustainable activity. The London Protocol Amendments permit cross-border CO2 transport. And national support programmes in Norway, the Netherlands, and the United Kingdom create financial incentives for investment.
Geological geography: The best geological storage sites are frequently offshore – depleted gas and oil fields in the North Sea, saline aquifers off the Norwegian coast. Sea transport connects onshore emitters with these storage sites across distances that would make pipelines uneconomical.
The technical demands of LCO2 carriers lie in the particular physical properties of liquid CO2. Tank design, material selection, and safety logic must be matched to the specific conditions – and these differ considerably from other gas transport applications.
The greatest technical challenge is pressure control. Liquid CO2 is typically transported at temperatures between -30 and -50 °C and pressures of 7 to 20 bar. This pressure range requires tanks that must be significantly more robust than for LNG (atmospheric pressure) or LPG (moderate pressures). Simultaneously, the temperature must be precisely maintained, as a temperature rise leads to a pressure increase that could exceed the tank design rating.
Material selection is another critical factor. CO2 in combination with moisture forms carbonic acid, which is corrosive. All wetted components must be specified accordingly. Furthermore, CO2 behaves differently from other gases during leaks: it is heavier than air and can accumulate in enclosed spaces – a significant safety risk requiring specialised detection and ventilation systems.
Scaling from small pilot sizes (several thousand cubic metres) to industrial sizes (30,000 to 50,000 m³) is not trivial. Larger tanks mean higher structural loads, more complex thermal management systems, and more demanding loading/discharging operations. The industry is still in an early learning phase here.
LCO2 carriers represent a distinct growth path with industrial logic. For the maritime market, this yields several conclusions. First: this is not a temporary trend but a structural market development driven by regulatory obligations and geological necessities. Second: the technical requirements are high enough to create a natural entry barrier. Third: early competence development in this segment pays off in the long term.
Current LCO2 carrier designs can be categorised into three main types, differing in tank type, transport conditions, and scalability.
Type C pressure tanks (cylindrical): The most widespread concept for small to medium-sized carriers. The cylindrical pressure tanks offer inherent safety through their pressure resistance and enable transport at medium pressures (15-20 bar) and moderate temperatures (-25 to -35 °C). Disadvantage: the ratio of tank weight to cargo volume is unfavourable, limiting economic scaling.
Bilobe tanks: An advancement that combines two interconnected cylindrical cross-sections in one tank. This design better utilises the available vessel cross-section and enables larger cargo volumes within the same hull. Northern Lights' first carriers use this concept.
Low-pressure concepts: For industrial volumes (above 30,000 m³), concepts with lower transport pressure (7-10 bar) and deeper temperatures (-45 to -50 °C) are being developed. These enable lighter tank structures and better volume utilisation but require more demanding temperature management and more capable cooling systems.
The choice of tank concept has direct implications for the entire logistics chain. Different pressure levels require different terminal equipment for loading and discharging. Standardisation would be desirable but is not yet emerging – a risk for early investors.
Regarding propulsion, a trend towards LNG or methanol as vessel fuel is emerging. The irony is evident: a CO2 transport vessel running on conventional heavy fuel oil undermines the credibility of the entire chain. Dual-fuel concepts with the option for CO2-neutral fuels are therefore likely to become standard.
For traditional shipowners, the LCO2 segment offers both opportunities and risks. The opportunities lie in a growing market with long-term charter contracts – CCS projects need reliable transport for decades. The risks lie in the technical novelty and dependence on regulatory and political frameworks.
Owners with gas transport experience – LPG, ethylene, or small LNG carriers – have a natural advantage. Many core competences are transferable: tank management, pressure control, cargo planning, and safety systems. Nevertheless, the differences are large enough to require a standalone learning curve.
Crew requirements are an underestimated factor. LCO2 carriers require crews with gas tanker experience and additional qualifications for handling CO2. The training market for these qualifications is still developing – a bottleneck that could delay scaling of the segment.
The charter market structure will likely be dominated by long-term time charter or contract of affreightment agreements. Spot markets are unlikely in the early phase, as vessel numbers are small and routes are project-bound. For owners, this means: stable income but lower flexibility.
Northern Lights – a joint venture of Equinor, Shell, and TotalEnergies – is the world's first commercial CCS project with a maritime transport component and thus the most important reference for the emerging LCO2 carrier segment.
In Phase 1, two purpose-built LCO2 carriers are deployed, transporting CO2 from emitters in Norway and the Netherlands to the storage site in the Johansen Formation beneath the Norwegian Continental Shelf. The vessels have a capacity of 7,500 m³ each and use bilobe pressure tanks.
The experience from Northern Lights provides the industry with valuable data: operational availability, loading rates, energy consumption, port dwell times, and safety records. These data will form the basis for the next generation of LCO2 carrier designs.
Phase 2, which envisions scaling to 5 million tonnes per year, will require larger vessels and a broader customer base. The experience from Phase 1 will feed directly into Phase 2 specifications – a process the entire industry is following attentively.
For shipowners considering entry into the LCO2 segment, a structured assessment approach is recommended.
Competence analysis: Which existing capabilities are transferable? Gas tanker experience is the strongest starting point. Without this foundation, entry involves significant learning and investment costs.
Project commitment: LCO2 carriers in the early phase are deployed project-bound. Entry therefore requires attachment to a concrete CCS project with secured financing and a robust timeline.
Technology choice: The decision for a tank concept has long-term consequences. A vessel designed for 15 bar transport pressure cannot readily be deployed in a 7-bar chain. Coordination with the project and terminal is therefore decisive.
Regulatory clarity: The flag state regime, classification society, and national CCS legislation of the target market must be assessed. Regulatory uncertainties can delay projects by years.
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