Another important question is where to store the amounts of CO2 during the process of carbon sequestration. Scientists believe that the most suitable places are old gas and oil fields. Storing CO2 in these places has the additional economic advantage of making it easier to access the remaining oil reservoirs. By injecting carbon dioxide underground, oil is pushed from the pores of rock to wells where it can be easily drained.
However, depleted oil and gas fields are not so many and cannot cover the amount of CO2 that needs to be sequestrated. This is why many geologists argue that the best places to store CO2 are sedimentary rocks that contain salty water (brine). The best sedimentary formations are those located at a depth of 800 meters or more. These layers are far below the resources of drinking water and are suitable for storing CO2.
While sedimentary rocks are almost everywhere and are easy to access, concern remains of whether these formations are safe enough. Small raptures of the overlying rock may allow for CO2 to reach the upper layers of the ground causing pollution. These concerns lead scientists to think that probably the best places for carbon sequestration are rocks underneath the oceans. High pressure from the water would keep CO2 safe preventing it from being released into the sea. This method is more expensive but it is more secure. Also for power plants that are located near the sea, storing CO2 under the ocean can be a practical and economic solution.
Another way for carbon sequestration is to direct CO2 directly to the oceans. Though the environmental consequences of this method are questionable, it is a process that resembles natural methods of carbon sequestration that occurred in the past. In older geological times when carbon dioxide increased to high levels, the increased concentrations went into the ocean formed limestone. In similar ways engineers may direct carbon dioxide into the ocean to create natural rock formations. The validity and ecological soundness of this method of course remains to be proved
There are many methods to achieve carbon sequestration and as technology progresses there will be even more. But let’s keep in mind that carbon sequestration is only one way to reduce greenhouse emissions. Combined efforts on many other promising fields may be needed in order to reduce pollution and achieve sustainable development.
What is your opinion on carbon sequestration as a way of reducing greenhouse gas emissions? Tell me about it in the comments below.
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