A number of countries worldwide have implemented regulations regarding CO2 storage into national laws with the intention to help efforts to reduce greenhouse gas emissions. This report provides an extensive overview of the regulatory frameworks related to operational and safety risks of geological CO2 storage in countries where the process of implementation has developed furthest (EU, UK, Norway, USA, Canada, Australia), and of applicable international conventions. For the EU region, the main focus is placed on the CCS Directive, which has already been transposed into national legislation in 20 of the 28 the Member States. The materials presented discuss regulations in relation to risks during different stages of the CO2 storage site lifetime and considering specific activities or events that may occur, i.e. site operation, potential leakage events, monitoring, remediation, closure and post-closure.

Risks concerning CO2 storage operation can be classified as health, safety and technical risks, which may occur in the local environment and be affected by injection activities, the CO2 stream composition, pressure and temperature. The operational phase of a storage site, when large amounts of CO2 are handled, is generally considered as a higher risk phase, as the introduction of CO2 into the reservoir poses a large change to the reservoir conditions. Regulations are, therefore, most advanced for this phase.

Storage site integrity and by extension leakage prevention during CO2 storage operation is important for both the success of a CCS project, in order to ensure that there are no significant adverse effects on the environment and human health. Different potential leakage pathways (natural and manmade) each pose different possible risks. Monitoring requirements that exist in all legislations are stream volume, pressure and temperature, in order to determine the amount of CO2 injected. Under the CCS Directive, when leakage is identified, the CO2 released into the air or into the water column needs to be quantified according to the ETS Directive Monitoring and Reporting Guidelines.

In case of leakage, indirect effects of CO2, such as acidification, are also important. Additionally, the mobilisation of contaminants such as heavy metals, and the presence of trace elements in the CO2 stream pose an appreciable risk. Therefore, to prevent infrastructure corrosion and additional risk, the CO2 stream should consist overwhelmingly of CO2 and should contain only traces of other substances. In Europe, it is specifically forbidden to add any substances, with the exception of those used for monitoring. Natural emissions of CO2 into the environment, at analogue sites, can and are being studied extensively in order to assist in setting CO2 storage related emission limit. However, currently there are no general safety regulations for CO2 concentrations in the environment, except for occupational guidelines.

Monitoring is necessary to provide a guarantee that stored CO2 remains contained, and to identify leakage. In every regulation that was reviewed, regular monitoring reporting to some kind of competent authority is requested, as is notifying this authority in case of a significant irregularity. The definition of a competent authority itself differs from one country to another. A large difference also exists between on- and offshore storage. For onshore storage, the focus lies mainly on protecting valuable groundwater resources, while this is not important for offshore storage.

An overview of (publicly available) monitoring plans of a limited number of active and non-active integrated CCS projects is also provided in this report. Measurement, monitoring and verification are the most important steps in risk management for CO2 storage. A long list of monitoring techniques are available and under development for specific parts in specific situations. In order to deal with the specific nature of geology, it is preferred that requirements for monitoring in regulations are risk- and objectives-based, site specific and non-prescriptive in the selection of monitoring techniques. Though differences can clearly be identified, all examples follow this site-specific and risk-based approach for defining the monitoring plan. In all cases mainly (existing) wells were identified as potential leakage hazards.

Possibilities for remediation in case of leakage form an integral part of risk management regulations for CO2 storage. Unexpected reservoir behaviour and potential leakage can have a natural (geological) or man-made (accidents, engineering) cause. A number of remediation measures are available from oil and gas production experience. These measures are generally applicable to man-made causes, mainly to problems with well leakage. Remediation measures for the geological system are rather limited and only partially effective. These include reservoir pressure management and injection of substances for blocking CO2 migration.

The different risk and safety aspects are closely related and therefore the same regulations are in many cases applicable to multiple aspects. On the other hand, different regulations are often applicable to a certain aspect or region, which leads to some issues in unclear and occasionally contradicting legislation.

Several documents are available that regulate the different aspects of storage risk. At international level, the London Convention and London Protocol were installed to protect the marine environment from disposal of waste. Geological storage of CO2 is, unlike storage of CO2 in the water column, is not considered as waste disposal. Under the United Nations Convention of the Law of the Sea (UNCLOS) it is, however, not clear if offshore geological storage of CO2 is regarded as waste disposal. A consensus between the UNCLOS Convention and the London Convention and Protocol is recommended to clarify the legal status of offshore storage.

For the EU, the CCS Directive and the ETS Directive apply directly to the geological storage of CO2. Other related regulations are those for waste, waste transport and (ground)water. Offshore, the OSPAR Convention for the protection of North-East Atlantic marine environment also applies to storage risks. Similar to the UNCLOS Convention, the Marine Strategy Framework Directive (MSD) in the EU does not mention CCS explicitly, but such activities might fall under the definition of pollution.

In the US, regulatory competence resides both on federal and state level authorities. At federal level, the US EPA Underground Injection Control fits under the Safe Drinking Water Act. A comparison of regulations revealed some monitoring and liability issues that still need to be clarified. Moreover, there is no mention of a long-term stewardship or a public register of storage sites.

In Canada, jurisdiction is also split between federal and provincial level, with regulations currently present in four out of ten provinces. In Alberta for example, the Alberta Carbon Capture and Storage Statutes Amendment Act and Carbon Sequestration Tenure Regulation provide an enabling framework and storage project regulations respectively. Additionally, a CCS Regulatory Framework Assessment was initiated to identify regulatory gaps and make recommendations.

A different approach was taken in Australia, where amendments are made to the existing petroleum legislation under the Commonwealth Offshore Petroleum and Greenhouse Gas Storage Act. Again, state-specific regulations exist as well. In general, Australian legislation is more prescriptive towards measurement, monitoring and verification requirements in comparison with other countries.

Independently form legislation, the IPCC has issued guidelines for the operation of a CO2 storage site. The IEA also have issued guidelines for implementing CCS regulation into national laws, that is the IEA Model Regulatory Framework.

While the EU regulation is entirely focused on emission reduction objectives, regulations in the US seem more focused on the utilisation of CO2 (CCUS) including enhanced oil recovery (EOR). Combined CCS and EOR are allowed under the EU CCS Directive, but it are strictly regulated.

Two general pathways of implementing regulations for CO2 storage risk management are implemented in the various international jurisdictions. Either a completely new set of regulations is adapted, or existing laws on environment and subsoil use are adjusted. In general, all regulations have the following corresponding requirements regarding risk management:

  • The CO2 stream must be pure, and any other incidental substances cannot be added with the aim of waste disposal.
  • Monitoring of the storage site is required before (baseline), during, and after injection.
  • Any leakage should be prevented. The exact definition of leakage however differs significantly.
  • In case of irregularities, competent authorities have to be informed and measures must be taken according to a risk management plan.

Main differences exist in the definition of the storage volume, periods, liabilities, liability transfer, requirement of monitoring techniques, and technical requirements for site closure (e.g. thickness of cement plugs).


Based on this regulatory overview, several issues regarding CO2 storage risk legislation could be identified. A number of these are already addressed by the instances involved. Recommendations are given here with the objective to facilitate permitting and administration, but also to create more transparency on liabilities and to facilitate the commercial introduction of CCS.

  • Because regulations on storage are elaborate and newly introduced, overlaps with other national and international legislations exist that interfere and sometimes contradict them. Overlaps generally occur between specific and non-specific CCS legislation such as those for water or waste management. These overlaps need to be properly addressed, and care must be taken to ensure transparent and stable regulations for the (storage) operators. Most overlapping legislations are currently undergoing revision.
  • Leakage is not uniformly defined in different regulations. This should pose no direct problems, but again different and contradicting regulations might apply to the same project. Moreover, diffuse leakage may be present but not detected with the monitoring equipment used in the monitoring time interval. Such situations are currently insufficiently addressed.
  • The utilisation of CO2 (CCUS, EOR etc.) could provide the business case for jumpstarting wide-scale deployment of CCS technology and appropriate and transparent regulations should be available. Complementary regulations between oil and gas production and CCS activity is therefore needed. In general, developing a CCS legislation can benefit from experience in the oil and gas industry and legislation.
  • For all legislations the long-term liability provisions need further revision and consolidation. There are few prescriptions of the requirements during the closure and post-closure stages, as there are no projects within this timeframe yet. Better definitions of necessary tasks would lead to better understanding of expectations on the operator's part. Especially under the USEPA regulations there is no description of transfer of liability for long-term stewardship after site closure, while this aspect receives significant attention in the EU CCS directive.
  • Specifically for the EU, the ETS Directive contains minimum competency requirements for the verifier of the monitoring and risk assessment reports. In the CCS Directive however, there is no mention of such requirements. It may be worth considering the introduction of standards for verification bodies regarding their knowledge, experiences, independency etc. This may result in the introduction of an accreditation procedure for verifiers under the CCS Directive at different levels (national, international).
  • Uncertainties are a specific issue in geology. It should be clear how these uncertainties should be handled and the the confidence levels are required in modelling as well as the accuracy levels required in the monitoring used to verify modelling results. Uncertainty management and confidence/accuracy requirements on all storage aspects should be included and set realistically, for a given storage site setting.
  • Currently, there is no obligation to keep a public register of storage sites under the US EPA regulations, nor in the IEA MFR guidelines. Although the level of disclosure that is necessary is still under discussion, such a register could increase public confidence.

This review has revealed that for countries that have a dedicated CCS regulation, although some issues still exist, most risks are covered. For countries looking to implement regulations, guidelines exist and installed legislation can serve as an example. Because CCS is a relatively new technology, experience will also guide new regulations. As investment and environmental risks are large, regulators need to be sure that risks are properly managed and operators need to be confident that liabilities are covered.