Has CCS Really Got Us Covered?


It is widely said and preached that one is responsible for one’s actions, but little do we pay attention to our actions towards our atmosphere. To cut it short, the ever-increasing temperature, scorching heat from the Sun and unbearable summers are all due to us-the humans. It may come to us as a shock, but it is the truth. Hotter days are the consequence of global warming. Global warming is the unusual rapid increase in the average temperature of earth. The Earth is getting hotter and hotter day by day due to human activities. Human inventions which involve burning fossil fuels(coal, oil, and natural gas) for industrial and domestic purposes is one of the major causes of global warming as combustion of these release methane, nitrogen oxides, hydrofluorocarbons, perfluorocarbons, etc.  but most importantly carbon dioxide (CO2).

Even though carbon dioxide is a natural greenhouse gas which helps sunlight reach the Earth but it also prevents some of the heat from radiating back into space but this is a natural process to keep the Earth’s temperature within limit otherwise we would have frozen to death. But the main concern here is that we are adding extra carbon dioxide in the atmosphere by combustion of fossil fuels which is causing great problems to deal with. Scientists are burning the midnight oil to address this pressing issue and save our planet. They have come up with ways to prevent carbon emissions by using carbon-free devices and if not prevent then at least with ways to get rid of this extra carbon dioxide that we have added and continue to add in the environment.

One of the ways that lets 90% of the carbon dioxide to get rid of is Carbon Capture and Storage (CCS). This technique collects the carbon dioxide from the emission sources, transports it to a storage location -underground and/or underwater and “dumps” it there. The method of Carbon Capturing has been in use for many years or to be precise for decades to get speedy recovery of oil and gas in industries, but it is only now that scientists have thought it to use for environmental reasons.

Carbon Capturing is done using three ways. All of them prevent up to 90% of the carbon dioxide from making the atmosphere toxic. One of the ways is ‘post-combustion capturing’ which lets us capture carbon dioxide after the fossil fuels are burnt. In the technique, a ‘filter’ can be added to the power-plant and the job is done. It allows us to modify the old plants with low expense. The second method is ‘pre-combustion capturing’ in which the carbon is collected before the fuel is burned. Unfortunately, this method is costly because new plants must be employed. The last and third method is ‘oxy-combustion capturing’ which separates carbon dioxide form steam after the fuel has been burnt in oxygen.

After the carbon capturing process comes the transportation step. Carbon dioxide can be transported in three states-solid, liquid, and gaseous. Solid CO2also known as dry ice, is very hazardous and sometimes fatal so it is very dangerous to transport, it would require huge manpower and it is also not very much friendly monetarily. So, transporting carbon dioxide in solid state is not feasible.  It is also possible to transport carbon dioxide in liquid state through ships and tankers butliquid carbon dioxideneeds low pressure and a constant low temperature, so cargo tankers or ships must be both pressurized and refrigerated. For that special mechanisms ought to be installed which is again not very pocket friendly but still in use as it does not go very hard on budget. The last option is to transport it in gaseous form. This is the best possible option and widely in use because in gaseous form, carbon dioxide is transported through pipelines which can be installed anywhere- underground or underwater (on sea-beds). A compressor compresses the gas all the way through the pipeline and moves it forward. Occasionally, a pipeline will have compressors after a measured distance to keep the gas moving and avoid any interruption. The CO2 must be free of any impurities and moisture or else, it can corrode the pipes. But pipelines built from stainless steel are said to have a low risk of corrosion.

As much as this method of transportation sounds easy and feasible, it is not. The reason being that this is a new method and there is not much data regarding this. There have not yet been many accidents due to mishandling or pipe leakage but the ones that occurred have gone without much harm. If there is leakage of carbon dioxide at a place, a condition called asphyxiation is common. It is shortness of breath due to lack of oxygen and excess of carbon dioxide. Carbon dioxide is a colorless and odorless gas. To avoid accidents due to leakage one thing that can be done is to add color and odor to the gas before transporting.

The last step in this method is storing the carbon dioxide. There are three possibilities to store carbon dioxide- in deep geological formations, underwater and in the form of mineral carbonates.

Considering storing carbon dioxide as mineral carbonates which is done by reacting CO2 with naturally occurring magnesium and calcium to form their respective carbonates which are very stable so there is no possibility of re-formation of carbon dioxide but this is a very slow process under normal conditions. It requires high temperature and pressure along with some catalyst. Once it is done then we are good to go.

The second option of storing it under water also seems quite promising but the environmental effects are believed to be very terrible. The excess carbon dioxide in the water reacts with water to form carbonic acid which leads to acidification of oceans. Also, the extra carbon dioxide in the water acts as asphyxiant and breathing becomes difficult for marine organisms. The last option is to store it underground. Carbon dioxide is stored in deep geological formations known as geological sequestration. In this technique, carbon dioxide is converted to ‘supercritical carbon dioxide’ which is a runny liquid. It is then injected into sedimentary rocks and the runny liquid then seeps into them underground. Various physical and geochemical mechanisms prevent carbon dioxide from escaping.

Although ‘Carbon Capture and Storage’ technique seems like a miracle solution, but it is important to keep in mind that it is not a permanent solution. It is just a way to get rid off already present carbon dioxide and we surely should not emit more and more carbon dioxide in the atmosphere thinking that CCS has got it all covered. It should be given keen intention that we should still come up with ways and devices with little or no carbon emission. Fossil fuels should not be used anymore. Rather than wasting time and money on coming up with ways to get rid of carbon dioxide being emitted, our goal should be to get invested in replacing fossil fuels with alternatives which has less adverse effects to the environment.

Mehre Taban
Mehre Taban
Mehre Taban is currently doing a degree of bachelor’s in electrical engineering from CEME, National University of Science and Technology.


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