See also:
http://www.ecojustice.ca/media-centre/press-releases/sask.-family-demands-answers-on-carbon-capture-and-storage-risks
This does raise the question - if these entirely new problems were not
caused by the CCS, what was it?
It looks a bit like air and water contamination from fracking. The gas
cos say it's nothing to do with them - but if it's not them, then why
did the problems suddenly kick off the moment fracking started?
Anyway, as Olaf says, you can chemically sequester CO2 from the
atmosphere in Mg silicate bearing rock for about $10/tonne. So what's
the point in the 30% extra coal burn, the expensive chemical
engineering, the pipelines, and the non-zero hazard anyway?
Oliver.
On 17/10/2014 16:39, Hawkins, Dave wrote:
On the Weyburn leak claims, these were promptly investigated and determined to
not be related to the Weyburn field operations. See a summary here:
http://switchboard.nrdc.org/blogs/bmordick/investigations_find_no_evidenc.html
Sent from my iPad
On Oct 17, 2014, at 6:58 AM, Schuiling, R.D. (Olaf)
<[email protected]<mailto:[email protected]>> wrote:
Researchers also calculated that the CO2 pumped into the Weyburn field could
never escape. Fortunately it is a very thinly populated area so only a number
of cattle and wild animals died when it started to leak. I am not claiming that
all potential CCS would start to leak, but there are safer ways to capture CO2.
There is no reason to capture CO2 from coal fired plants, you can capture it
anywhere, so go for the safest and cheapest solution(see attachment), Olaf
Schuiling
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]] On Behalf Of Andrew Lockley
Sent: donderdag 16 oktober 2014 16:52
To: geoengineering
Subject: [geo] Storing greenhouse gas underground--for a million years |
Science/AAAS | News
http://news.sciencemag.org/chemistry/2014/10/storing-greenhouse-gas-underground-million-years
MARC HESSE
Storing greenhouse gas underground--for a million years
When Canada switched on its Boundary Dam power plant earlier this month, it signaled
a new front in the war against climate change. The commercial turbine burns coal,
the dirtiest of fossil fuels, but it traps nearly all the resulting carbon dioxide
underground before it reaches the atmosphere. Part of this greenhouse gas is pumped
into porous, water-bearing underground rock layers. Now, a new study provides the
first field evidence that CO2 can be stored safely for a million years in these
saline aquifers, assuaging worries that the gas might escape back into the
atmosphere."
It's a very comprehensive piece of work," says geochemist Stuart Gilfillan of the
University of Edinburgh in the United Kingdom, who was not involved in the study. "The
approach is very novel."
There have been several attempts to capture the carbon dioxide released by the
world's 7000-plus coal-fired plants. Pilot projects in Algeria, Japan, and
Norway indicate that CO2can be stored in underground geologic formations such
as depleted oil and gas reservoirs, deep coal seams, and saline aquifers. In
the United States, saline aquifers are believed to have the largest capacity
for CO2 storage, with potential sites spread out across the country, and
several in western states such as Colorado also host large coal power plants.
CO2 pumped into these formations are sealed under impermeable cap rocks, where
it gradually dissolves into the salty water and mineralizes. Some researchers
suggest the aquifers have enough capacity to store a century's worth of
emissions from America's coal-fired plants, but others worry the gas can leak
back into the air through fractures too small to detect.
To resolve the dilemma, geoscientists need to know how long it takes for the
trapped CO2 to dissolve. The faster the CO2 dissolves and mineralizes, the less
risk that it would leak back into the atmosphere. But determining the rate of
dissolution is no easy feat. Lab simulations suggest that the sealed gas could
completely dissolve over 10,000 years, a process too slow to be tested
empirically.
So computational geoscientist Marc Hesse of the University of Texas, Austin,
and colleagues turned to a natural lab: the Bravo Dome gas field in New Mexico,
one of the world's largest natural CO2 reservoirs. Ancient volcanic activities
there have pumped the gas into a saline aquifer 700 meters underground. Since
the 1980s, oil companies have drilled hundreds of wells there to extract the
gas for enhanced oil recovery, leaving a wealth of data on the site's geology
and CO2storage.
To find out how fast CO2 dissolves in the aquifers, the researchers needed to
know two things: the total amount of gas dissolved at the reservoir and how
long it has been there. Because the gas is volcanic in origin, the researchers
reasoned that it must have arrived at Bravo Dome steaming hot--enough to warm
up the surrounding rocks. So they examined the buildup of radiogenic elements
in the mineral apatite. These elements accumulate at low temperatures, but are
released if the mineral is heated above 75°C, allowing the researchers to
determine when the mineral was last heated above such a high temperature. The
team estimated that the CO2 was pumped into the reservoir about 1.2 million
years ago.Then the scientists calculated the amount of gas dissolved over the
millennia, using the helium-3 isotope as a tracer. Like CO2, helium-3 is
released during volcanic eruptions, and it is rather insoluble in saline water.
By studying how the ratio of helium-3 to CO2 changes across the reservoir, the
researchers found that out of the 1.6 gigatons of gas trapped underground at
the reservoir,only a fifth has dissolved over 1.2 million years. That's the
equivalent of 75 years of emissions from a single 500-megawatt coal power
plant, they report online this week in the Proceedings of the National Academy
of Sciences.
More intriguingly, the analysis also provided the first field evidence of how CO2 dissolves after
it is pumped into the aquifers. In theory, the CO2 dissolves through diffusion, which takes place
when the gas comes into contact with the water surface. But the process could move faster if
convection--in which water saturated with CO2 sinks and fresh water flows into its place to absorb
more gas--were also at work. Analysis revealed that at Bravo Dome, 10% of the total gas at the
reservoir dissolved after the initial emplacement. Diffusion alone cannot account for that amount,
the researchers argue, as the gas accumulating at the top of the reservoir would have quickly
saturated still water. Instead, convection most likely occurred.Hesse says constraints on
convection might explain why CO2 dissolves much more slowly in saline aquifers at Bravo Dome than
previously estimated, at a rate of 0.1 gram per square meter per year. The culprit would be the
relatively impermeable Brava Dome rocks, which limit water flow and thus the rate of convective CO2
dissolution. At storage sites with more porous rocks, the gas could dissolve much faster and
mineralize earlier, he says.Even so, the fact that CO2 stayed locked up underground for so long at
Bravo Dome despite ongoing industrial drilling should allay concerns about potential leakage, Hesse
says. Carbon capture and storage "can work, if you do it in the right place," he says.
"[This is] an enormous amount of CO2 that has sat there, for all we can tell, very peacefully
for more than a million years."
Posted in Chemistry, Earth
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