Carbon Capture, Usage and Storage (CCUS) enables CO2 produced across the economy to be stored safely and permanently deep beneath the seabed typically at depths greater than 800 metres, either in depleted oil and gas fields or saline aquifers. At these depths, CO2 is stored in offshore rock formations known as reservoirs, which are structured like a sponge and sealed by impermeable cap rock above. A typical geological storage site can permanently hold tens of million tonnes of CO2. (1) Geological CO₂ storage has been in operation globally for decades; although not yet deployed at scale within the UK, there are many examples globally of secure CO₂ storage. Norway, for example, has been storing CO2 offshore since 1996, with over 20 million tonnes of CO2 stored.(2)

To unlock sufficient CO2 storage capacity to meet Carbon Budget and Net Zero targets (3), potential CO2 storage sites will need to go through extensive appraisal, permitting and development activities. These activities increase confidence that a store can permanently and safely store CO2. If exploration and appraisal activity demonstrate that a site is suitable for CO2 storage, this site can then be permitted, developed and used pending commercial agreements.

Independent technical analysis commissioned by Government shows very high long-term containment confidence (4) with a typical project expected to retain over 99.9% of injected CO₂ over a 125-year period. Minor leak rates have a low probability of occurring whereas major leak rates have a very low probability of occurring. Therefore, the likelihood of damage to the marine ecosystem is considered to be very low. This is a central reassurance for the public and a key consideration in site selection and operational oversight. These assessments also consider risks associated with onshore and offshore CO₂ pipelines, which are regulated to the same high standards as other major hazard pipelines.

The UK has a comprehensive, multi-regulator regime overseeing the safe deployment of CCUS. The North Sea Transition Authority (NSTA) is the technical regulator for offshore CO₂ storage and has granted permits for the HyNet and East Coast Cluster projects (5), issuing permits only where there is no significant risk of leakage or harm to the environment or human health. Before any permit is approved, the Offshore Petroleum Regulator for Environment and Decommissioning (OPRED), on behalf of the Secretary of State, undertakes the required Environmental Impact Assessment, including public consultation, which takes into account any potential environmental impact of the proposals including any impacts on marine protected areas. The NSTA cannot issue a permit without the Secretary of State’s agreement to OPRED’s assessment. The Health and Safety Executive (HSE) is the national regulator for workplace health and safety, covering offshore activities and the operation of pipelines, and regulates the health and safety of CCUS operations both onshore and offshore. Duty holders must identify and control risks, and HSE applies a goalsetting, targeted, proportionate and evidence based regulatory approach under the Health and Safety at Work etc. Act, with interventions that support duty holders to meet their legal responsibilities. Alongside these controls, environmental regulators in England and the Devolved Administrations issue environmental permits for onshore activities ensuring robust environmental protection across all onshore elements of CCUS projects.

Storage site operators are subject to strict legal obligations to monitor stored CO2 and report on storage performance throughout the operational lifetime of a project and after sites are closed. The NSTA assesses proposed monitoring plans, which must, include monitoring during the operational lifetime of the project and the 20-year post-closure period once operations have ceased. In accordance with UK legislation, offshore CCUS infrastructure must be removed when decommissioned at the end of its operational lifetime, further reinforcing confidence in CO₂ containment for storage sites that receive a storage permit.

The UK does not plan to pause the development of CCUS, as full independent safety, environmental and legal assessments are already carried out for each storage site, and the UK has a strong regulatory environment to deploy CCUS safely.

Footnotes:

(1) Intergovernmental Panel on Climate Change (2018)
(2) Equinor, Sleipner CO₂ Storage Project Overview
(3) The Seventh Carbon Budget - Climate Change Committee
(4) https://www.gov.uk/government/publications/deep-geological-storage-of-carbon-dioxide-co2-offshore-uk-containment-certainty
(5) Under Chapter 3, Part 1 of the Energy Act 2008, Ministers in the Devolved Administrations are the licensing authorities for CO₂ storage activities that fall within devolved competence, including onshore storage and, in Scotland, the territorial sea, while the NSTA remains the licensing authority for storage on the UK Continental Shelf.

Department for Energy Security and Net Zero