3 POTENTIAL LEAKAGE EVENTS - RELATED REGULATIONS AND GUIDELINES
This chapter presents an overview of the international
regulations and guidelines related to potential leakage events of
CO2 from a geological storage site, an overview of the
international regulations and guidelines related to leakage, as
well as the effects of CO2 reaching the biosphere.
The chapter starts with a review of the main international acts
and agreements that regulate the risk of CO2 leakage,
the London Convention and Protocol, OSPAR, EU Directives on
Geological Storage of CO2 and ETS. These international agreements
were elaborated at different times and differ mostly on their focus
(e.g. OSPAR focuses only on the effects of CO2 leakage
in the marine environment whereas EU Directive on Geological
Storage of CO2 refers to CO2 leakage in all
environments) and geographical coverage (although they overlap to
some extent with regards to this). Still, all regulations require
that storage operations are conducted in a safe manner, taking
corrective measures in case of leakage. For this reason, they also
stipulate the necessity of conducting a thorough risk assessment in
each step of a storage project (starting with the pre-operational
phase) in order to prevent and mitigate the identified hazards.
In this context, another important part of the chapter refers to
guidelines for risk assessment, especially the ones developed under
OSPAR (FRAM) and EU CCS Directive (Guidance Document 1). These
guidelines comprise several stages for risk assessment, covering
the entire cycle of a CO2 storage project, starting from
site characterisation to risk management (including monitoring and
corrective measures).
A first step in the risk assessment for a CO2
geological storage site is to identify all of the potential risks
related to the site, especially the potential leakage pathways,
presented within this chapter, such as permeable caprock, faults
and fractures, wells and other anthropogenic pathways (e.g.
hydraulic fracturing of reservoir possibly connected to a
CO2 storage site or extension of fractures to the
CO2 storage complex).
The final part of the chapter presents the effects of a
potential CO2 leakage on the environment and on human
safety and health through a few studies made on this topic using
natural analogues (e.g. Laacher See, Germany; Panarea Island,
Italy) and some incidents and regulations related to human and
animal exposure to increased levels of CO2. Although the
exact effects of a CO2 leakage are not yet known (as the
composition of CO2 stream and the re-actions of
co-injected elements play an important role in this issue and there
is still a research need for controlled CO2 leakage), it
is commonly accepted that CO2 leakage can cause
acidification of sea or groundwater, mobilisation of toxic elements
(due to pH change in soils), adverse effects on plants, animals and
humans.
The risks of leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column are regulated through several acts and international agreements such as the London ConventionInternational convention on the prevention of marine pollution by dumping of wastes and other matter, which was adopted at London, Mexico City, Moscow and Washington on 29 December 1972 and Protocol, OSPARConvention for the Protection of the Marine Environment of the North-East Atlantic, which was adopted at Paris on 22 September 1992, EUEuropean Union directives on Geological storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere of CO2Carbon dioxide and the ETSEmissions Trading System, defined in the EU ETS Directive 2003/87/EC amended by Directive 2009/29/EC Directive. The regulatory regimes require that storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere operations are conducted in such a manner that any hazards are prevented or mitigated and also that necessary corrective measures must be taken in the case of leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column.
According to the ECEuropean Commission directive a storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site shall not be chosen if there is significant riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event of leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column of the stored CO2Carbon dioxide.The riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event of leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column from a site with a storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere permit has therefore been restricted and the site conditions delimited from the very beginning. Site characterisation is the first step in the process of choosing the most appropriate storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site with no significant riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event of leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column. During this process all potential leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column pathways should be identified and their implications then assessed during the risk assessmentA process intended to calculate or estimate the risk to a given target, part of a risk management system process. The riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event analysis is a major part of this assessment process and is important when deciding on an appropriate storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site.
The second step in leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column prevention is the implementation of a comprehensive, site-specific monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions plan covering the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere site and the surrounding area (including the sealAn impermeable rock that forms a barrier above and around a reservoir such that fluids are held in the reservoir and overlying marker formations) (i.e. the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere complex). The main purpose of monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions is to permit control of the CO2 plumeDispersing volume of CO2-rich phase contained in target formation behaviour and to discover and prevent any potential leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column at an early stage. The data acquisition performed during monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions will also provide new high quality information that will continuously improve the static and dynamic characterisation of the storage(CO2) A process for retaining captured CO2, so that it does not reach the atmosphere complex. Further details on monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions can be found in CGSCO2 Geological Storage; Injection accompanied by storage of CO2 streams in underground geological formations. Key Report 1 (Rütters et al., 2013).
The effects of CO2Carbon dioxide reaching the biosphere are not yet fully understood. However, it is widely known that CO2Carbon dioxide leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column may cause acidification of sea water, groundwater resources and soils. The change in pH also mobilises environmentally toxic elements in soils such as lead. An important issue with respect to the effects of leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column is the composition of CO2 streamA flow of substances resulting from CO2 capture processes, or which consists of a sufficient fraction of CO2 and sufficiently low concentrations of other substances to meet specifications of streams permitted for long term geological storage and the reactions of the coCarbon monoxide-injected substances. There are many lessons to be learned from natural analogues of CO2Carbon dioxide leakage(in CO2 storage) The escape of injected fluid from the storage formation to the atmosphere or water column and from laboratory experiments as wellManmade hole drilled into the earth to produce liquids or gases, or to allow the injection of fluids as the catastrophic events of Lake Nyos and Monoun in Africa which demonstrated the importance of understanding potential hazards in order to mitigate them fully.