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HSE challenges with large-scale CCS identified

A new report for the Petroleum Safety Authority Norway identifies relevant health, safety and environmental concerns associated with large-scale carbon capture and storage (CCS).


The study concludes that none of the identified HSE challenges and potential hazards will represent any substantial hindrance for implementing and applying CCS. This is conditional on the risks being assessed and managed in a full and satisfactory manner.

Also covering the transport aspects of such developments, the report has been compiled for the PSA by Norwegian classification society Det Norske Veritas (DNV).

It has identified and charted the potential hazards of CCS on the basis of available knowledge, experience and industrial practice.

As part of the study, a workshop was also conducted with relevant stakeholders from industry and the regulatory authorities in Norway.

This work is one of several technical studies launched by the PSA to establish risks related to CCS and associated transport, and to clarify where more information is needed.

Expectations
Large-scale CCS has aroused substantial expectations both in Norway and internationally as a potentially substantial contribution to reducing global warming.

Plans in Norway call for large amounts of carbon dioxide to be captured from gas-fired power stations at the Kårstø processing plant north of Stavanger and the Mongstad refinery near Bergen.

These developments call for the captured gas to be piped offshore for storage in geological formations beneath the seabed.

Categories
Generally speaking, the potential hazards and challenges of CCS projects can be broken down into three categories:

  • challenges related to carbon transport by pipeline (internal and external corrosion, hydrate formation, load distribution over free spans, and propagating fractures)
  • material challenges, including liquefied carbon dioxide’s solvent properties and material compatibility, and elastomers – in other words, the need in part to tailor materials to the acidic properties of the liquefied gas
  • operational and design challenges, including formation of carbon solids, pressure reduction (both controlled and uncontrolled) low temperatures, failure of pressurised systems and boiling liquid expanding vapour explosion (Bleve) conditions – in other words, how carbon dioxide behaves in extreme conditions such as a combination of high pressure and temperatures.

The DNV report concludes that it should be possible to adapt existing risk management strategies to handle the potential hazards in an acceptable manner.

Assuming that restrictions on applicability are known and respected, guidelines, standards, best practice, experience and knowledge from existing industry can also be used by the relatively young CCS sector.

The challenge facing this nascent business and the regulatory authorities is to identify where these restrictions are to be found.

Understanding
Some gaps have been identified in knowledge and experience. These need further work to improve understanding and to ensure reliable design and operation throughout the CCS value chain.

A critical problem is the lack of validated impact models for liquefied/super-critical carbon dioxide. The report accordingly recommends additional studies and development work on testing models and theories about carbon behaviour under different conditions.

Knowledge is also lacking about the way impurities in the carbon flow affect corrosion and phase transition parameters. This should be studied in more detail.

Expertise
Norway has long experience of processing and transporting oil and gas in various forms by pipeline, and this expertise forms the basis for national work on CCS.

But carbon dioxide differs from petroleum in a number of respects. By posting the DNV study to its website, the PSA also aims to contribute actively to disseminating relevant knowledge about CCS to all relevant recipients at home and abroad.

Contact person at the PSA:
Torleif Husebø, discipline leader for process integrity
E-mail: torleif.husebo@ptil.no