Where’s the T in CCGS?
THE RECENT international seminar in Salvador, Brazil*, on the subject of carbon dioxide capture and geologic storage (CCGS) gave rise to a number of interesting discussions as participants were updated on the latest views and research in this important area. CCGS – or, perhaps more usually, CCS – is a subject of widespread importance and frequent discussion, although there seem as yet to be few solutions to either the ‘capture’ or the ‘geologic storage’ problems. Some of the figures for quantities of CO2 that will need to be both captured and stored are breathtaking in their size, and thy are followed by unanswered questions about how long-term storage (is this a hundred years, a thousand years, an aeon?, and who will have the responsibility for managing the process?) is to be effected. Another interesting aspect of the event, which seems to be echoed at similar discussions around the world, was that of the 150 or so papers and presentations, only eight referred to the elephant-in-the-corner issue of transportation of the CO2 from the capture site to the storage site: hence the title of this editorial.
Arguably, CCGS – or CCTGS – is not the right route to be followed to reduce the effects of global warming, and there are many other fora in which this is being debated. But if it is accepted that CCTGS plays a part, than the transportation aspect is huge. The sheer quantities of CO2 that will need to be transported will probably considerably exceed the amount of natural gas and crude oil that is currently being transported by pipeline world-wide, requiring a vast new international pipeline network to be constructed from scratch. The deadlines being quoted for carbon emissions’ reduction mean that this network will need to be implemented in the next ten years or less, and the pipelines themselves will be long-distance, and through developed regions where routeing will itself be a major issue. The long-distance aspect is of particular relevance, as the regions and strata suitable for geologic storage are all far from the locations where the carbon dioxide is being emitted.
A further aspect is associated with the fact that the gas to be transported will not be pure naturally-occurring CO2, which is currently being transported by pipeline without problem in a number of places. It will be so-called ‘anthropogenic’ CO2 (i.e. man-made), and it will by no means be pure if its origins are power-station and industrial sources. The uninitiated might think: “a gas is a gas, CO2 is all around us, so what’s the problem?”. But CO2 is a difficult gas to move by pipeline, and even minor impurities make it far more problematic.
The Journal is privileged in this issue to have been able to publish three significant papers on aspects of CO2 transportation by pipeline, written by international experts who have informed views of the issues involved. Dr Mo Mohitpour of Tempsys Pipeline Solutions in Canada and co-authors from TransCanada PipeLines introduce the subject with their wide-ranging overview of the current status of CO2 transportation, and some of the design aspects that it will be necessary to accommodate if large-scale CO2 pipelines are to become a reality. Following this, Professor Jose Luiz de Medeiros of Rio de Janeiro’s Federal University and colleagues discuss two models that have been developed to design CO2 pipelines; taking as a starting point the McCoy model, the authors examine in detail the advantages and disadvantages of this ‘base-case’, and go on to introduce their newly-developed approach which they consider is more attuned to the actual situation that will be faced by pipeline designers in this context. They acknowledge that this is only a step towards a fully-flexible solution, postulating that further work will be required properly to incorporate all of the varying parameters that are necessary.
The third paper on the general subject is from Dr Andrew Cosham of Atkins Boreas in the UK and Robert Eiber of his eponymously-named consulting firm in Columbus, USA. This paper delves further into the technicalities of pipeline design for CO2 transportation, and examines the issue of fracture propagation. The authors point out that fracture propagation control will require careful consideration in the design of a CO2 pipeline, which may be considerably more susceptible to long-running ductile fractures than natural gas pipelines. The need to prevent such propagating fractures imposes either a minimum required toughness or a requirement for mechanical crack arrestors and in some situations the requirement for fracture propagation control will dictate the design of a CO2 pipeline. The issues are illustrated in examples involving the design of an 18-in and a 24-in pipeline, and the authors conclude that if fracture control is considered early in the design, any constraints on the design can be identified and, in principle, resolved without too much difficulty.
The two further papers in this issue relate to pipeline rehabilitation. Professor Jorge Reis ad colleagues from the Universidade Federal Fluminense at Niteroi in Brazil, in association with Petrobras’ research institution CENPES, describe their work on scientifically analysing epoxy repair systems for carbon-steel pipelines. They conclude that while composite repair systems may not be totally effective for certain circumstances (in particular, through-thickness corrosion defects), they have identified a simple and systematic methodology for repairing leaking corrosion defects in metallic pipelines with epoxy resins. Finally, Sidney Taylor of Incal Pipeline Rehabilitation (based in France, Russia, and the USA) discusses in detail a rehabilitation project on the CPC pipeline in Kazakhstan, were 60km of the line has been recoated and refurbished using a somewhat unusual technology.
*2nd International Seminar on Carbon Capture and Geological Storage, Salvador, Brazil, 9-12 September, 2008. Organized by Petrobras University, Rio de Janeiro.
Performance of European cross-country oil pipelines
BRUSSELS-based CONCAWE – the oil companies’ European association for the environment, health, and safety in refining and distribution – has for the last 36 years been collecting spillage data on European cross-country oil pipelines, paying particular attention to spillage volumes, clean-up and recovery, environmental consequences, and incident causes. As many readers will be aware, the results of these surveys have been published in annual reports since 1971, and form a most important statistical record. CONCAWE’s latest report, published in August*, covers the performance of these pipelines in 2006, and includes a full historical perspective going back to 1971. The performance over the complete 36-year period is analysed in various ways, including gross and net spillage volumes and spillage causes, which are grouped into five main categories: mechanical failure, operational, corrosion, natural hazard, and third party. The rate of inspections by intelligent pigs is also reported.
Approximately 70 companies and agencies operating oil pipelines in Europe currently provide data for this annual survey. These organizations operate 159 pipeline systems which, at the end of 2006, had a combined length of 35,390km, slightly more than the 2005 inventory; the difference is mainly due to corrections in the reported data. The volume transported in 2006 was 805m cum of crude oil and refined products, a figure which has been stable in recent years; total traffic volume in 2006 was estimated at 130 x 109 cum km.
There were 12 spillage incidents reported in 2006, corresponding to 0.34 spillages per 1000km of line. This is slightly above the five-year average but well below the long-term running average of 0.56, which has been steadily decreasing over the years from a peak of 1.2 in the mid 1970s. There were no reported fires or fatalities – but one injury – connected with these spills. The gross spillage volume was 726cum, equivalent to 0.9 parts per million (ppm) of the total volume transported: this corresponds to 21cum per 1000km of pipeline, and compares favourably with the long-term average of 57. Nearly 99% of the spilled volume was recovered or disposed of safely.
Most of the reported pipeline spillages were small, and just over 5% of the spillages since 1971 have been responsible for 50% of the gross volume spilled. Pipelines carrying hot oils (such as fuel oil) have, in the past, suffered very severely from external corrosion due to design and construction problems. Many have been shut down or switched to cold service, and the great majority of the pipelines included in this review now carry unheated petroleum products or crude oil.
Half the 2006 incidents were related to mechanical failures, four to third-party activities, and two to corrosion. Over the long term, third-party activities remain the main cause of spillage incidents, although it has been progressively reduced over the years. Mechanical failure is the second largest cause of spillage; after great progress in reducing this during the first 20 years of the reviews, the frequency of mechanical failure has been following an upward trend since the mid 1990s. Most of the European pipeline systems involved were constructed in the 1960s and 1970s. CONCAWE points out that in 1971, 70% of the inventory was 10 years old or less; by 2006, only 7% was 10 years old or less, and 37% was over 40 years old. However, this ageing does not appear to have led to any increase in spillages.
Over the complete survey period (from 1971) the two most important causes of spillages are third-party incidents and mechanical failure, with corrosion well back in third place and operational and natural hazards making minor contributions. Significantly, third-party incident frequency has been reduced progressively over the years although, having made good progress prior to 1991, it appears that this trend might subsequently be reversing.
In 2006, 78 runs by all types of intelligent pig covered 7020km of pipeline. Most inspection programmes involved the running of more than one type of pig in the same section, so that the total actual length inspected was around 4776km (13% of the inventory). Overall, there is no evidence to show that the ageing of the pipeline system poses any greater level of risk, and CONCAWE concludes that the development and introduction of new techniques, such as internal inspection using intelligent pigs, holds out the prospect that pipelines can continue operating reliably for the foreseeable future. Continued monitoring of the CONCAWE pipeline performance statistics will be necessary to confirm the position.
*Performance of European cross-country oil pipelines: a statistical summary of reported spillages in 2006 and since 1971. Published by CONCAWE, Brussels, www.concawe.org.
Subscriber on-line access
WE ARE PLEASED to confirm that on-line access for subscribers to the Journal is now operational at www.j-pipe-eng.com, and all subscribers should have received a personal letter giving them the user names and passwords required. Please contact the publishers (see page 234) in case of difficulty or if the letter has not arrived. The site contains both this current issue, and all previous issues, in pdf format; issues can be downloaded in their entirety as a single pdf, or the individual papers can be downloaded separately. We hope that this resource proves helpful to subscribers, and enhances the reputation and influence of the Journal.
We are shortly also to introduce on the site an automated process for paper submission, in which authors will be able to upload abstracts and receive acceptance or rejection messages rapidly and efficiently. The refereeing of papers will be managed through this procedure, and we hope that its introduction will improve the effectiveness and speed with which such matters are currently implemented.