Concept study to offload onboard captured CO₂

To explore conditions for storing and handling captured CO₂ onboard ships, as well as its offloading onto reception facilities

• Develop concepts to safely offload onboard captured CO₂

• Assess current port infrastructure for liquefied CO₂ (LCO₂) offloading

• Generate capital expenditure (CAPEX) and operational expenditures (OPEX) models for LCO₂ offloading infrastructure and buildout

• Review and identify gaps in custody transfer, competency standards and regulatory approval

• Review policy and regulatory regimes and identify ports that allow offloading

• Validate and finalise findings with stakeholders across value chain

Onboard storage of captured CO₂

• The liquefaction and storage of onboard captured CO₂ under the following conditions are both viable commercial options, using semi-refrigerated Type C tanks:

◦ low pressure (LP; 5.7 to 10 bara at -54.3 ºC to -40.1 ºC), or

◦ medium pressure (MP; 14.0 to 19.0 bara at -30.5 ºC to -21.2 ºC).

• Storage in ISO tank containers, at conditions of 18.0 to 24.0 bara at -25.0 ºC to -20.0 ºC, is another option.

• LCO₂ poses unique safety challenges, such as asphyxiation due to oxygen displacement and toxicity at higher exposure levels (>7%) from leaks and loss of containment.

Offloading concepts

• Four offloading concepts covering key offloading modalities were studied.

◦ Concept 1: Ship-to-liquid bulk terminal

◦ Concept 2: Ship-to-floating CO₂ storage with intermediate LCO₂ receiving vessel

◦ Concept 3: Ship-to-liquid bulk terminal with intermediate LCO₂ receiving vessel

◦ Concept 4: Ship-to-terminal with ISO tank containers

Regulatory and policy analyses

• The policy and regulatory landscape for offloading captured LCO₂ from ships is immature.

• The London Protocol, which provides a regulatory framework for CO₂ transport and related carbon credits between countries, presently does not cover the transfer of CO₂ captured in international waters to a country.

• The International Convention for the Preventing of Pollution from Ships (MARPOL) Convention does not account for onboard captured CO₂ as a waste stream.

• IMO guidelines on life cycle GHG intensity of marine fuels (LCA guidelines) account for OCCS in its tank-to-wake (TtW) emissions factor calculations, but methodological guidance on how captured CO₂ is accounted has yet to be developed.

• European Union Emissions Trading System (EU ETS) allows ship owners to offset their emissions with onboard captured CO₂, provided it can be certified that the CO₂ is permanently stored or utilised in accordance with legislation requirement.