Carbon capture and storage (CCS) is a long-established technology but its profile has grown as a potentially significant solution to achieve rapid decarbonisation. Gard highlights the associated risks and opportunities for the shipping industry.
The scale of the opportunity
As explained, it is estimated that global CCS capacity must increase 120 times from current levels by 2050, rising to at least 4.2 gigatonnes per annum, for countries to achieve their net-zero commitments. Whilst pipelines will generally offer a more cost-efficient option where there is sufficient scale and regularity of supply of CO2, carriage by sea is more appropriate for longer distance transport (over approximately 350km), flexibility of quantity, source and injection locations. Estimates of global offshore storage capacity range from 2,000 to 13,000 gigatonnes of CO2. Regions such as Korea, Japan and the North Sea, which have subsea storage locations and coastal-based emissions, are likely to be suitable for seaborne carriage of CO2. If onboard carbon capture is widely adopted, this will require carriage by sea from temporary port-based to permanent storage locations.
One of the leading CCS schemes is the Norwegian government-sponsored Longship project. This includes capturing CO2 from industrial sources in the Oslo-fjord region (from cement, chemicals and energy) and shipping liquid CO2 from these industrial capture sites to an onshore terminal. From there, the CO2 will be transported by pipeline to an offshore subsea storage location in the North Sea. It has recently signed contracts to receive about 1.2 million tonnes CO2 annually from the Netherlands (Yara Sluiskil) and Denmark (Orsted power stations). Northern Lights is responsible for developing and operating the CO2 transport and storage facilities for the project. Phase one is due to be operational in 2024 with an annual storage capacity of up to 1.5 million tonnes of CO2.
The limited size of the CO2 fleet
Although CO₂ has been carried by sea since the late 1980s, there are currently only four CO₂ vessels. All are operated by Larvik Shipping, a Norwegian company. These vessels trade on short-haul routes within Europe, carrying food-grade CO₂. The quantities carried are modest; the largest vessel can carry only 3,600 cubic metres (cbm), approximately 1,770 tonnes.
Globally, there are reported to be five vessels on order. Three ships, each of 7,500 cbm, are being built at Dalian shipyard, PRC, for the Northern Lights project. Capital Gas Ship Management has speculatively ordered two far larger 22,000 cbm CO2 carriers which are also designed to be able to carry LPG and ammonia. These are being built at the Hyundai Mipo shipyard, South Korea with anticipated delivery in 2025-2026. Since they have no specific CCS project to fulfil, their multi-capability means they will have the flexibility to undertake carriage of other liquified gases.
Practical issues and risks of CO2 carriage
CO2 has unusual characteristics which make it a challenging cargo to carry. It requires both pressure and refrigeration to be carried in liquid form. The higher the temperature, the higher the pressure required, and vice versa. The most efficient option, in terms of technology and cost, for transport is in a compressed liquid state, close to the so-called ‘triple point’ (-56.6oC, 5.18bar): the temperature and pressure at which solid, liquid, and gaseous forms of CO2 coexist in thermodynamic equilibrium. This brings with it the risk of freezing during operations, and so safer handling may dictate a slightly higher temperature and pressure.
