Cross-border CO₂ transport and storage networks in Europe through "arrangements" under the London Protocol

As the world transitions to a low-carbon future, carbon capture and storage (CCS) technologies are a critical component of efforts to decarbonise key energy and industrial sectors while reducing hard-to-abate atmospheric CO₂ emissions. Given that onshore geology is often unsuitable for CO₂ storage, the availability of extensive offshore storage opportunities increases the likelihood that states will utilise offshore geological formations located on the continental shelf for this purpose. However, offshore geological storage capacity varies significantly between states, leading some to seek access to their neighbours’ continental shelves for CO₂ storage. In Europe, regional CO₂ storage cooperation has resulted in bilateral agreements, formalised as non-legally binding memoranda of understanding (MoUs), to facilitate cross-border CO₂ transport and storage. These arrangements provide a structured yet flexible framework for fostering cooperation among states involved in such projects. However, they also raise legal questions, particularly regarding compliance with international legal obligations, including European Union (EU) and European Economic Area (EEA) law. This article examines the legality of cross-border CO₂ transport and storage networks in Europe. It analyses the legal challenges posed by the general prohibition on waste export, the conditions under which cross-border CO₂ transport and storage may be permitted, and the role of bilateral arrangements in fostering regional cooperation. It also explores the interaction between international legal frameworks—such as the London Protocol and UNCLOS—and regional instruments, including the EU CCS and Emissions Trading System (ETS) Directives. The article argues that, despite their non-binding nature, these MoUs demonstrate the parties’ intention to implement their obligations under the London Protocol, UNCLOS, and other applicable international law. Furthermore, this practice has been adopted by several European states without objection from other states or international judicial scrutiny. As such, these MoUs may have interpretative value as a supplementary means of interpretation under the Vienna Convention on the Law of Treaties, potentially influencing the application of existing treaty obligations related to cross-border CO₂ transport and storage. Finally, this article considers the challenges of transposing the European legal framework to other regions exploring similar cross-border CO₂ networks.