When captured from heavy carbon-generating industries, carbon dioxide can be stored permanently underground in geological reservoirs of porous rock. The most suitable reservoirs for CO2 storage are depleted oil and gas reservoirs or deep saline aquifers. There are precise requirements for storing CO2, including reservoir type, well design and permitting, and the need for long-term monitoring.
When it comes to storing CO2 offshore, a number of global conventions have been historically in place to protect marine environments from the impact of human activities. One of the first is the "Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972", the "London Convention" for short, which has been in force since 1975
In 2006, the London Protocol replaced the convention with a more precautionary approach. Instead of black and grey lists of what could not be dumped, the London Protocol uses a reverse. Dumping of any materials not on the reverse list requires a permit. The protocol ensures effective control of marine pollution sources and prevents waste dumping. All dumping is prohibited, including the geological sequestration of CO2 offshore. Exceptions were made for certain categories of wastes or other materials, including dredged material, fish waste and inert, inorganic geological material.
However, later that year, the UK, Norway and other countries proposed that CO2 streams from carbon capture processes for geological sequestration be added to the list of materials that may be considered for dumping. This amendment went into force in 2007, providing the legal basis for permanently isolating CO2 in sub-seabed geological formations. This amendment did not address the cross-border export of CO2, which remained prohibited to stop countries exporting waste to countries that have not signed the London Protocol.
Norway, having built the world's first industrial-scale CCS project, Sleipner CCS, proposed in 2009 to tackle the prohibition of export and cross-border shipping of CO2. The amendment to Article 6 of the London Protocol stated "the export of carbon dioxide streams for disposal" may occur as long as "an agreement or arrangement" has been entered into by the countries concerned. Accordingly, the proposal stipulates that the countries involved in the cross-border transport of CO2 must enter into bilateral agreements or understandings, and that all the Protocol's other protection standards and requirements have been met.
There are currently 53 Parties to the Protocol. However, only the following countries have signed the 2009 amendment. They are Norway, the UK, the Netherlands, the Islamic Republic of Iran, Finland, Estonia, Sweden, Denmark, Korea, and Belgium. Article 21 of the London Protocol requires a two-thirds majority vote which has not been obtained. The amendment is, therefore, as yet not ratified and cannot be considered to be formally in force.
In 2019, Norway and the Netherlands addressed the lack of ratification by using the Vienna Convention on the law of treaties. The convention allows for agreement between nations to be applied provisionally if the treaty allows this and the negotiating states have both agreed in some manner.