Excessive greenhouse gases, such as carbon dioxide, are warming the planet. Given that such pollution will probably continue into the near future, it's important to think about how to remove this stuff from the atmosphere.
Removing carbon dioxide from the atmosphere.
Much research has focused on how to remove carbon dioxide pollution that's already in the atmosphere. Trapping carbon dioxide in abandoned oil wells is a common proposition.
However, the gas will probably leak from such a site on a relatively short time scale. Thus, the problem of atmospheric cleanup is delayed, rather than solved.
More promising is recent research that has investigated the possibility of entrapping carbon dioxide in peridotite (a type of volcanic rock) in Oman. Carbon dioxide reacts with water and the minerals in the rock, permanently entrapping the carbon dioxide in mineral form (metal carbonates).
Such entrapment, in some location where weathering won't dissolve the rocks (releasing carbon dioxide), holds much promise for securely removing carbon dioxide from the atmosphere. Identifying locations around the world where this may be realistically feasible is a logical first step of this research field.
Dennis Kent (Rutgers University) and coworkers have contributed to the need for methods of permanent atmospheric cleanup by investigating the potential of underground porous basalt (another volcanic rock) formations along the North American east coast for long-term, secure carbon dioxide storage. The location of these formations (near major metropolitan areas) enhances the practical nature of the scientists' proposal.
Possible locations for carbon dioxide storage.
There are several possible locations in and near the United States for secure carbon dioxide storage. The geology of the Newark Rift Basin is known in the greatest detail.
Here, there is a porous (approximately 15% porosity) inner basalt layer, deep within the earth, from 830 to 880 feet deep. It is sandwiched between layers of much less porous basalt and sediment.
Thus, carbon dioxide can be pumped into this inner porous layer, and won't come back out. There's nowhere for it to go.
The Long Island Rift Basin is another possible location for carbon dioxide storage. The scientists propose that it might be possible to store the total forty-year carbon dioxide emissions of several one gigawatt coal power plants in this location, but the geology needs to be confirmed experimentally.
The South Georgia Rift Basin holds the most promise as a reservoir for storing large amounts of carbon dioxide, because it's as large as the other mentioned rift basins combined. However, again, the geology needs to be confirmed experimentally.
Immediate prospects.
What scientists need to do now is to experimentally confirm the geology (porosity of the inner basalt layer) of these rift basins, initially at cost-effective study sites. Once the extent of the porous basalt layers is known, one must also be careful to avoid zones that may still be geologically active, which may be expected to release their stored carbonate (carbon dioxide) in the event of seismic activity.
The most effective method of cleaning up carbon dioxide pollution is to stop the pollution in the first place. However, on a realistic level, alternative methods of dealing with the problem need to be investigated, and the work of these scientists offer hope for cleaning up some of the pollution that's already in the atmosphere.
for more information:
Goldberg, D. S., Kent, D. V., & Olsen, P. E. (2010). Potential on-shore and off-shore reservoirs for CO2 sequestration in Central Atlantic magmatic province basalts Proceedings of the National Academy of Sciences, 107 (4), 1327-1332 DOI: 10.1073/pnas.0913721107