This chapter identifies the risks related to the injection phase during CO2 geological storage and summarises the national, European and international legislation of CO2 geological storage and CCS-related legislations. The materials presented provide an overview of the risks arising during the CO2 storage operation phase. Risks are described with regards to their spatial extent and significance: local environmental risks, general operational risk, risks related to CO2 stream composition, pressure and temperature.

The directives and regulations relating to CO2 storage site operation are discussed with a special focus on dedicated CCS legislations at international, European and national levels where available. Besides the CCS specific regulations, the EU Emission Trading Directive, the International Climate Change Legislation and Clean Development Mechanisms and their relations to CO2 storage site operation phase is considered. Next, the directives and regulations relating to offshore and onshore CO2 storage site operation are presented, followed by brief conclusions.

During storage operation, the CO2 is transported from the source location(s) and injected into the storage reservoir according to the volumes and rates specified in the site development plan (Groenenberg et al., 2009). The site operation phase (Fig. 2-1) is one of the most important periods from a risk management perspective, because large scale commercial CO2 injection into the storage complex is initiated and conducted and the risk of irregularities and potential leakage as a result of the injection project is highest. During the site operation phase, the migration and movement of CO2 may follow different pathways as the plume develops and expands, and pressures start to increase, also affecting risk evolution (ICF, 2011).

O. Fig . 2-1

Fig. 2-1: Phases of CO2 storage site operation (Groenenberg et al., 2009).

The storage operation activity follows several licencing procedures, i.e., site investigation, drilling and storage licencing procedures, which infer the use of a 3D geological model, a monitoring plan and that detailed risk assessment has been carried out. The key aspects of the operation phase are the need to evaluate the degree to which the site is performing as expected according to predictive models that have been used to carry out performance assessment and evaluate the evolving containment risks through on-going risk assessments. Performance and risk assessments should be carried out at intervals determined in discussion with the regulator (at least once a year according to the EU CCS Directive (2009/31/EC).

With on-going monitoring, there will be a continuous flow of new information and data about the project and its performance. The monitoring plan and activity are essential parts of the risk management approach. The results from injection and monitoring should be used by the operator to verify, test and iterate the risk assessment, validate models and performance predictions iteratively. The results may require that operational parameters and limits stated in the original site development plan be adjusted to reflect updated understanding of the storage performance (Fig. 2-2). The results must also be reported to the competent authority in line with the CCS Directive. The CCS directive also requires a range of necessary actions and safeguards to be in place because of the risk arising from the injection of large volumes of CO2.

O. Fig. 2-2

Fig. 2-2: Risk Management based approach to storage project (EC, 2011a).


in depth

2.1 Risks arising during CO2 storage operation

The following sections focus on types of risks (physical, chemical and biological conditions and accidents) arising duri...

2.2 Directives and regulations relating to CO2 storage site operation

The Global CCS Institute hosts a Carbon Capture Legal programme (CCLP), which was originally started in 2007 by Universi...

2.3 Conclusions

When the injection period starts, the storage site is allowed to inject CO2 within certain site-specific license conditi...