Supercritical CO2 boosts super optimism in sequestering greenhouse gas
November 17th, 2008
Shafts of calcite mineral grow rapidly on basalt after exposure to supercritical CO2 for 30 days. Use of dual beam focused ion beam scanning electron microscopy at the Environmental Molecular Sciences Laboratory helped capture the formation of the calcite. Image: PNNL
(PhysOrg.com) -- Scientists appear to have the rock-solid evidence that suggests carbon dioxide can be safely and permanently sequestered in deep, underground basalt rock formations, without risk of it eventually escaping to the atmosphere. The findings have potential implications for sequestering carbon in other reservoir systems as well.
Researchers at the Department of Energy's Pacific Northwest National Laboratory have discovered key factors that show water-saturated liquid CO2, under conditions mimicking deep geologic settings, will plug cracks within the rock that otherwise might allow the hazardous greenhouse gas to escape.
"The implications of this discovery are far reaching," said PNNL scientist Pete McGrail. "Sufficient molecular water is apparently present in the supercritical CO2 phase to carry out multi-step reactions directly with minerals in the basalt. In essence, the carbon dioxide can self-seal undetected cracks or fissures that might allow the CO2 to migrate vertically to shallower depths."
Recently, McGrail exposed samples of basalt rock under high pressure to the two phases of CO2 that would exist after injecting it deep underground. The two phases include CO2-saturated water and water-saturated liquid CO2 or CO2 gas in a supercritical phase. Previous tests exposed basalt to CO2-saturated water, which forms over time as injected CO2 interacts with existing water in the porous and permeable basalt layers. However, these previous experiments ignored reactions to rock samples exposed to CO2 in a supercritical phase, which is dehydrated for transport by pipeline, but will absorb water from the surrounding basalt formation after injection.
McGrail presents his findings Tuesday, Nov. 18, at the 9th International Conference on Greenhouse Gas Technologies.
Scientists hoped the experiments would shed light on how both forms of CO2 might react with minerals found in the layers of basalt thousands of feet below the earth's surface, and if it would impact the speed in which the CO2 mineralized, thus affecting its stability.
McGrail's research, funded by the Department of Energy's Office of Fossil Energy and National Energy Technology Laboratory, revealed that water-saturated liquid CO2 - CO2 gas in a supercritical phase - showed similar or even greater reactivity than observed for CO2-saturated water. The swift chemical reaction detected on metal and oxide surfaces, as well as the silicate surfaces found in basalt rock, were surprising and impressive according to McGrail.
Current reservoir simulation tools are quite sophisticated in their ability to model complex sets of heterogeneous reactions in aqueous media, but are presently incapable of treating similar reactions in the liquid or supercritical CO2 phase itself. McGrail suggests a need for development of significant new modeling capabilities to analyze the chemical reactivity of water dissolved in the dense CO2 phase.
"Although these initial experiments focused on basalt, the principles are not unique to basalts and would apply generally to other reservoir systems and caprocks," McGrail said.
He also noted that pilot-scale field injections will help validate these bench-scale findings.
Provided by PNNL
Mar 05, 2009 |
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Also,power bills are high enough witout paying extra for this rubbish.
Added heat stress and less secure water availabillity for irrigation more than offset the potential benefits to agriculture of increased atmospheric CO2. CO2-fertilization has no beneficial effect on land that is not cultivated by humans because of fertilizer constraints(mainly phosphorous and nitrogen).
Now there's true science (NOT). Since when did "likely to be" become a scientific measure on which to base decisions affecting the future of the species? Ah, since you species-haters got access to communications, I guess.
Since the IPCC made it the gold standard?
Those 30% - 40% numbers are years old. New research by the National Energy Technology Laboratory, Alstom, and B&W is showing a drop in net output that is closer to 15% for oxy-coal systems with compressed cabon dioxide ready for sequestration. The energy recovered from sensible heat in oxy-coal (that is lost in normal flue gas) and latent heat from condensed moisture in the oxy-coal combustion product stream makes up the difference. That sensible and latent heat is lost in a normal power plant (where they avoid condensation to prevent corrosion and need the sensible heat to loft the exhaust plume) but can be recovered using oxy-coal. I suggest you update your rant by reading a little of the literature.
The current situation is that Hansen, Gore et al demand that we accept their model outputs and expert opinions based thereon. Sorry there approach is not real science. There model results and expert opinions are not facts, just opinions based upon hypothetical scenarios.
We owe it to ourselves to get scientific proof before we destroy our economy and squander a few trillion dollars while doing so.
Look out your window at the for sale signs. In case you have missed it, the free "market over all" mentality has already destroyed the economy (or do you believe: "the economy is still fundamentally strong?"). The science points to AGW. To rant about those on the far left is just as useless as ranting about those on the far right. The science is in the middle. The bottom line is that the science shows that we are increasing the CO2 levels. It also shows that CO2 fills the IR window left by water vapor. The result is that less IR can escape the earth. That was known more than 100 years ago in a very rough estimate (since corrected many times)by Arrhenius.
Check this link:
http://en.wikiped...rrhenius
What we don't know is how much this AGW effect will be and there are hundreds of scientists trying to make better estimates on this issue. It does little good for those on the left to declare an immediate disaster for mankind when there is little evidence to support that drastic conclusion (as you rightly point out) or those on the far right to dismiss a possible serious problem for our children (as you seem to do). Lets look closely at the science as it evolves, test the hypotheses as they pop up, and act responsibly to mitigate the risks that are discovered. That might easily include trillions of dollars in investment (as is going on right now trying to save the economy you seem to think is in good shape). ;-)
Here it is. The children argument. What's more liable to affect my children negatively for their life:
Growing up in the streets
or
A .8 degree F increase in seasonal temperature at the poles?