Summary/Abstract
Governments around the world are looking to ensure their transition to full low-carbon economies whilst tackling climate change by implementing offshore carbon capture and storage (CCS) – a method of permanently removing carbon dioxide (CO 2 ) from the burning of fossil fuels and burying it deep below the seabed in suitable geological formations. Among the main targets of such geological formations are depleted, or nearly depleted, offshore oil and gas reservoirs within existing oil-producing fields. However, such reservoirs will frequently transcend maritime boundaries and jurisdictions, i.e. a shared geological formation could be used on both sides of the maritime boundary for CO 2 sequestration and storage. This raises the potential for disputes among nations, transboundary environmental degradation, and business disruption. The paper discusses the role of CCS in the low-carbon energy transition, focusing specifically on international legal aspects related to the storage of CO 2 in sub-seabed geological formations of the continental shelf. Ongoing CO 2 storage projects are examined to showcase critical technical aspects, including reservoir selection, well design, and post-injection monitoring. The analysis highlights the need for international coordination in situations where CO 2 storage occurs across an international boundary and the importance of consent from all states with jurisdiction over the relevant CO2 storage formations. The paper concludes that existing maritime boundary agreements, including those with straddling deposit clauses, are unlikely to cover transboundary CO2 storage operations, except if they are considered incidental to ongoing petroleum operations.