Carbon, basic constituent of all living things is also one of the most commercially used element. Such high commercial use, especially as a source of Energy (Coal, Petroleum), gives out large quantities of waste product. Among these Carbon Dioxide is one of the most abundant one, released as a consequence of using fossil fuels for power generation. This has led to a rise in the overall atmospheric carbon dioxide and has led to warming of the earth, guiding humanity to its doom.
To protect ourselves we need to do 2 major things. Firstly, we must switch to green energy and secondly, we must find ways to reduce the level of Carbon Dioxide in the atmosphere. In 2015, representatives of various countries agreed to adopt the Paris Agreement which aimed at reducing the overall Carbon emission, reduce global warming and adopt green mean of Energy Production.
Natural Carbon Sinks
Before going into the details, let's first understand what a carbon sink is. A carbon sink is anything that absorbs more carbon than it produces. The two major natural carbon sinks are the ocean and the forest. Large amount of carbon dioxide is absorbed by the ocean. The biological uptake is negligible compared to the solubility uptake. Artificial deposition of carbon dioxide into ocean water may lead to acidification of it and cause harm to marine calcifying organisms. On the other hand, planting forests are also a good means of carbon capture. Carbon is captured in forms of wood and timber and stored for centuries in the soil. Carbon capture my natural means are fairly slow processes and under present circumstances needs human intervention. A green method would be to make wooden construction which would keep carbon away from atmosphere for centuries as well as prevent degradation of soil quality. Modern farming methods also help in decreasing the level of Carbon in the atmosphere, but it is negligible.
Artificial Carbon Capture
Scientists have stated that about 10 billion tons of carbon need to removed per year as per the 2019 report. Some biological methods, as described above are planting trees or to improve farming methods. But such means won't be enough at this hour. That is why countries started investing in chemical methods for carbon removal. Carbon capturing plants been set setup in the recent past with estimates of about 200 dollars per ton of Carbon capture. This is too much for commercial use, if it is about 150 per ton it could be commercialised. About 40k such plants are needed to make it possible. This process of carbon capture is called Direct Carbon Capture. In such a process a fan draws in air and passes it through a carbon capturing solution like certain hydroxides. This solution is concentrated and often Calcium Carbonate pellets are produced which can be used in 2 ways:-
- Buried is a safe place so causing a lessening of carbon in atmosphere. Since the net atmospheric carbon is reduced, this method is called Carbon Negative process.
- Used commercial. Often mixed with Hydrogen to produce a kind of automobile fuel which after combustion releases the Carbon back into the atmosphere. Such processes are called Carbon Neutral processes.
Our carbon dioxide production has reached from 1600 million metric tones to 36, 000 million metric tones since 1885. Since prevention is better than cure, it is often a good practice to not let carbon to be emitted into the atmosphere. In certain Industries the Carbon dioxide is separated out before the waste gases are led out into the atmosphere. The waste air is channelised through a solvent like ammonia to strip the air out of Carbon Dioxide, which can be then either put into oil mines or used commercially. Pre and post-combustion carbon capture prevent about 80-90% of the Carbon to enter the atmosphere.
Direct Carbon Capture
Well the fact remains that most of the Carbon Emission is due to transportation rather than industries. To tackle this kind of problem, recently some scientist from Harvard University and Bill Gates funded company claimed that they can capture carbon relatively cheaply at a rate of 94-232 dollars per metric ton of carbon capture. They not only suck the Carbon dioxide from the atmosphere, but also transform it into gasoline or jet fuel which can be used commercially to aid the factory. This makes it a carbon neutral process.
This kind of direct air capture starts with an air capture. Air containing Carbon Dioxide is sucked in and then passed through strong hydroxide solution and converted to carbonates .
In the next step, this concentrated carbonate solution is sent to a pellet reactor where it reacts with Calcium to form Calcium Carbonate in the form of dry pellets.
Then they are sent to a Calciner where they are heated to decomposition temperature where breaks down into Calcium oxide and Carbon Dioxide.
This Carbon Dioxide is then reacted with liquid Hydrogen and converted in liquid fuels like gasoline and jet-fuels.
Pros and Cons of Carbon-Capture
Storage of Carbon dioxide in the ocean bed, where it remains as a liquid like substance may be hazardous to the ocean life, on the other hand, storing them in oil mine may cause mass leakage of Carbon dioxide into the atmosphere. The Direct Carbon Capture is a good method but is Carbon Neutral by Nature somewhat like in the case of Plastic-to-Fuel conversion Tech. If we wish to turn this into a Carbon Reducing one, we need governments to aid its funding which is difficult with the high cost of the process. Moreover such plants need to be mass made in order to have a noticeable effect. Only after such a technology has been commercialised and spread among the masses can these be methods be effective. Since, we are just recycling the waste products, it gives a negative impact on moving to renewable, green sources and promote the oil Industries.
But in this point of time, any aid towards Carbon Control is welcomed and since there are seeming opportunities to use it commercially, such ideas are attracting investor and would be effective when used as popularly as Wind and Solar power capture techniques.
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