SciAm: Carbon Rock Lock

[bystander]

Carbon Rock Lock: Storing CO2 on the East Coast
From the March 2010 Scientific American Magazine

Sucking carbon dioxide and other greenhouse gases from smokestacks and burying them underneath the ground is a key technology cited by politicians and scientists as a way to help combat climate change. One open question is where best to store the CO₂. A recent analysis points to the volcanic rock off the East Coast of the U.S.

Such rock, known as basalt, might be better than other sites, such as deep saline aquifers or nearly empty oil wells, because the rock not only stores CO₂ but also over a relatively short period of years forms carbonate minerals out of it—in other words, limestone. And coastal basalt has the added benefit of having an overlying ocean, which acts as a second barrier of protection against the gas leaking out.

Green House Sponge:
Volcanic rock known as basalt converts CO₂ to carbonate minerals,
making the widely distributed substance ideal for carbon sequestration.
(Getty Images)

[bystander]

Storing carbon dioxide deep underground in rock form
PhysOrg | Earth Sciences | 17 June 2010

As carbon dioxide continues to burgeon in the atmosphere causing the Earth's climate to warm, scientists are trying to find ways to remove the excess gas from the atmosphere and store it where it can cause no trouble.
...
Carbon sequestration is currently the most promising way to reduce greenhouse gases. Gislason leads an international team of scientists on the Carbfix Project, which aims at pumping carbon deep underground in southwest Iceland where it will mix with minerals and become rock. The project's goal is to find a storage solution that is long lasting, thermodynamically stable and environmentally benign.

Geochemist raises questions about carbon sequestration
PhysOrg | Environment | 16 June 2010

As carbon dioxide levels in the atmosphere rise, policy makers and scientists are looking at new ways to tackle the problems associated with the greenhouse gas.

One method under much discussion is carbon capture and storage (CCS), otherwise known as carbon sequestration. CCS, a newly developing technology, involves injecting carbon dioxide underground to remove it from the Earth's atmosphere.

... current plans for carbon storage could benefit by paying more attention to the critical role of underground chemical reactions. For instance, when carbon dioxide comes into contact with water in underground aquifers, it can form a weak acid that will start to dissolve minerals in the rocks. According to DePaolo, research is needed to analyze how fast such reactions proceed and which minerals are affected to better gauge the efficiency of carbon storage projects.

[bystander]

Carbon sequestration: Boon or burden
PhysOrg | Earth Sciences | 27 June 2010

The idea to sequester carbon is gaining support as a way to avoid global warming. For example, the European Union plans to invest billions of Euros within the next ten years to develop carbon capture and storage whereby CO2 will be extracted at power plants and other combustion sites and stored underground. But how effective is this procedure and what are the long-term consequences of leakage for the oceans and climate? A Niels Bohr Institute researcher has now cast light upon these issues. This research has just been published in the scientific journal, Nature Geoscience.

Large scale use of carbon sequestration could help to avoid extreme global warming that would otherwise occur in the near future unless fossil fuel emissions are reduced significantly. But it is not clear how effective different types of sequestration are in the long run, owing to leakage of stored CO₂ back out to the atmosphere. Nor is it clear what would be the long-term consequences of such leakage for the Earth's environment.

Gary Shaffer, professor at the Niels Bohr Institute, and leader of the Danish Center for Earth System Science, made long model projections for a number of sequestration/leakage scenarios. His results show that leakage of the stored CO₂ may bring about large atmosphere warming, large sea level rise and oxygen depletion, acidification and elevated CO₂ concentrations in the ocean.

Storage of CO₂ in the deep ocean is a poor choice since this creates grave problems for deep sea life and since CO₂ stored this way returns to the atmosphere relatively quickly, bringing back the global warming.

Geological storage may be more effective in delaying the return of the warming and associated consequences but only if a CO₂ leakage of 1 % or less per thousand years can be obtained.

Long-term effectiveness and consequences of carbon dioxide sequestration

• Nature Geoscience, 27 June 2010 (online), doi: 10.1038/ngeo896

[bystander]

Carbon sequestration too leaky to stop global warming
ars technica | Nobel Intent | 06 July 2010

Carbon dioxide sequestration isn't a great global warming solution unless we develop less leaky equipment or commit to regular re-sequestering, according to a paper published in Nature Geoscience. If the containers used don't leak less than one percent every thousand years, atmospheric carbon would have to be monitored carefully and resequestered on a regular basis over tens of thousands of years in order to match the effects of reducing carbon emissions. Otherwise, sequestration would only slow the warming, not stop it.