Study relaunches debate on geological storage of CO2

[freddau]

Storing carbon dioxide emitted by industry in the earth's underground seems to be a promising option for combating the greenhouse effect. Provided that the leaks are minimal, if not zero. A study of an old Texan oil well suggests that it will have to be looked at twice. Injecting CO2 quickly changes the chemical composition of the environment, as a team led by Yousif Kharaka, from the United States Geology Service, found. It injected 1 tonnes of liquid CO600 under pressure into a 2 m thick aquifer pocket 24 m deep. Samples from this tank including brine then showed a change in its chemical composition: its acidity increased rapidly, which resulted in the dissolution of carbonates and other minerals.


"This could end up creating passages in the rock or sealing the wells, leading to brine and CO2 leaks," write the researchers in the July journal Geology. Various metals and organic compounds could follow the same path. "The environmental impact could be major if large volumes of brine accompanied by toxic metals migrated to drinking water," they warn. This conclusion remains provisional: six months after the experimental injection, no intrusion of carbon dioxide had been detected in the geological formation which covers the brine reservoir. The feared flight is therefore only hypothetical for the time being. But surveillance is maintained.

The stake is all the more important as deep saline aquifers are considered as the most promising CO2 receptacles. Their potential storage capacity is estimated at between 350 and 1 gigatonnes of carbon dioxide - to be compared to global emissions of human origin close to 000 gigatonnes per year. Do the observations of Yousif Kharaka and his colleagues challenge the various injection projects that point here and there? Yann Le Gallo, researcher at the French Petroleum Institute, does not necessarily see "bad news", even if he recognizes that the issue of CO30 leaks and the release of heavy metals "concerns the community of specialists in geological storage ".


WATERPROOFING


Nick Riley, of the British Geological Survey, coordinator of a European program on the subject (CO2GeoNet), is not worried: "The article by Geology gives a very oriented picture, in that it does not specify that the reactions chemicals from CO2 with fluids and surrounding rock also result in the deposition of minerals that block their circulation. " He cites the example of the Sleipner site in the North Sea, where the Norwegian company Statoil injects a million tonnes of CO2 into a saline aquifer annually without any leaks having been identified to date.

At the Weyburn site in Canada, the injection of CO2 into carbonate rocks also resulted in acidification of the medium for a few months, before returning to initial conditions. Again, no leaks were reported. Finally, insists Nick Reiley, the wells can be designed to guarantee carbon dioxide tightness.

"While we delay deploying this technology for fear of leaks, we allow 100% of the CO2 from fossil fuels to escape into the atmosphere. This will have disastrous consequences in terms of climate change, rising sea levels. and ocean acidification, "says Nick Riley." In this context, I think geological storage is a risk to take. We have little time left. "

By Hervé Morin

http://www.lemonde.fr/web/article/0,1-0 ... 635,0.html

[denis]

heads or tails? is the future of the planet a game ??
And very "serious" studies involve so much interest that they are not to be trusted!

[elephant]

basically, (it's the case to say it) what do we do with this CO³? bubbles to put in Perrier (I immediately send them my bill for advertising, rest assured!)