ISO/TC 265/WG 5 - Cross Cutting Issues

The primary aim of this document is to describe the main compositional characteristics of the CO2 stream downstream of the capture unit, taking into account common purification options. Accordingly, this document will characterize the different types of impurities and present examples of concentrations determined in recent capture pilot projects as well as through literature review. It identifies ranges of concentrations, giving priority to in situ measurements when available. The second aim of this document is to identify potential impacts of impurities on all components of the CCS chain, from surface installations (including transport) to the storage complex. For example, impurities can have a significant effect on the phase behaviour of CO2 streams in relation to their concentration. Chemical effects also include the corrosion of metals. The composition of the CO2 stream can also influence the injectivity and the storage capacity, due to physical effects (such as density or viscosity changes) and geochemical reactions in the reservoir. In case of a leakage, toxic and ecotoxic effects of impurities contained in the leaking CO2 stream could also impact the environment surrounding the storage complex. In order to ensure energy efficiency, proper operation of the whole CCS chain and not to affect its surrounding environment, operators usually limit the concentrations of some impurities, which can, in-turn, influence the design of the capture equipment and purification steps. Such limits are case specific and cannot be described in this report; however, some examples of CO2 stream specifications discussed in the literature are presented in Annex A. The required purity of the CO2 stream delivered from the capture plant will to a large degree depend on the impurity levels that can be accepted and managed by the transport, injection and storage operations. The capture plant operators will therefore most probably need to purify the CO2 stream to comply with the required transport, injection, storage specifications or with legal requirements. Monitoring of the CO2 stream composition plays an important role in the management of the entire CCS process. Methods of measuring the composition of the CO2 stream and in particular the concentrations of impurities are described and other parameters relevant for monitoring at the various steps of the CCS chain are described. The interplay between the set CO2 stream specifications and the efficiency of the entire CCS process is also explained. Finally, the mixing of CO2 streams coming from different sources before transport or storage is addressed, and the main benefits, risks and operational constraints are presented.

ISO/TR 27918:2018 is designed to be an information resource for the potential future development of a standard for overall risk management for CCS projects. The risks associated with any one stage of the CCS process (capture, transportation, or storage) are assumed to be covered by specific standard(s) within ISO/TC 265 and other national and/or international standards. For example, the risks associated with CO2 transport by pipelines are covered in ISO 27913. The scope of this document is intended to address more broadly applicable lifecycle risk management issues for integrated CCS projects. Specifically, the focus of this document is on risks that affect the overarching CCS project or risks that cut across capture, transportation, and storage affecting multiple stages. It needs to be noted that environmental risks, and risks to health and safety should be very low for CCS projects provided the project is carefully designed and executed. Risk identification and management is part of the due diligence process. A list of acronyms is included in Annex A. Clause 5 includes an analysis of how a CCS standard could address aspects of risk analysis that apply to all elements of the CCS chain, such as: - risk identification (identifying the source of risk, event, and target of impact)[1]; - risk evaluation and rating; - risk treatment; - risk management strategy and reporting. Clause 6 comprises an inventory of the overarching and crosscutting risks. These include issues such as: - environmental impact assessment; - risk communication and public engagement; - integration risks between capture, storage, and transportation operators, such as risk of non-conformance of CO2 stream to required specifications; - integration risks associated with shared infrastructure (hubs of sources, common pipelines, hubs of storage sites); - risks resulting from interruption or intermittency of CO2 supply and/or CO2 in-take; - risks associated with policy uncertainty; - incidental risks from activities related to the capture, transportation or storage processes without being specifically covered in the respective standards (e.g. management or disposal of water produced as a by-product of CO2 storage). Clause 7 describes implications and considerations for a potential standard on lifecycle risks for integrated CCS projects. [1]As defined in ISO 31000.

ISO 27917:2017 defines a list of cross-cutting terms commonly used in the field of carbon dioxide capture, transportation and geological sub-surface storage including through storage in association with enhanced oil recovery (EOR) operations. ISO 27917:2017 only deals with CO2 geological sub-surface storage. The terms are classified as follows: - general terms and definitions relating to carbon dioxide; - general terms and definitions relating to carbon dioxide capture, transportation and storage; - general terms and definitions relating to monitoring and measuring performance in carbon dioxide capture, transportation and geological storage; - general terms and definitions relating to risk; - general terms and definitions relating to relationships with stakeholders; A list of the main acronyms used is given in Annex A.