An EU-funded project called ECO2 has investigated the influence of CO2 seeping from the Norweigan CCS project by the Sleipner gas field in the North Sea. They have studied the seabed above the area where the CO2 has been injected, and have also gathered high-resolution seismic data of the geological layers above the storage area. What they found was one big crack 25 kilometres north of the storage area, and numerous vertical, smaller so-called pipes and chimneys in the rocks covering the CO2 storage site. Some of them went all the way down to the sandstone formation that contains the CO2. The researchers state that there is no evidence of any seepage from the CO2 injected through these cracks.1
Professor Peter M Haugan from the Geophysical Institute at the University of Bergen, Norway, says that this may be just a coincidence. No such research was conducted prior to the start of injection. The biggest crack (up to 10 metres wide and 3 kilometres long) could well have been situated right above the injection site. His conclusion is that this proves the need for very expensive exploration of sites intended for storage of CO2.2
The Sleipner gas field is seen by many as an example of a successful CCS project. However, the Sleipner CCS operation is a very special case, as stated in a report from AirClim published in 20083. The CO2 is extracted from fossil gas from the Sleipner gas field, which is cold and under very high pressure. Extracting CO2 from hot exhaust gases at atmospheric pressure from a fossil-fuelled power plant is a very different matter. This makes it difficult to use the Sleipner CCS, as well as the Snøhvit CCS in Northern Norway, as arguments in favour of CCS in general.
The Sleipner CCS started operating in 1996. Since then, about one million tonnes of CO2 per year have been separated from the natural gas extracted from the gas field. In total nearly 48 million cubic metres of CO2 have been injected into the sandstone since 1996.
1ECO2 Brochure (July 2014)
2Professor Peter M Haugan, Personal communication, 11 September 2014
3Last gasp of the coal industry (October 2008)