Carbon Capture Technologies

Carbon dioxide is everywhere and concentration is increasing day by day.

Carbon dioxide (CO2) concentration is currently at approximately 0.04%. That is one in 2500 molecules.?However, before the start of the Industrial Revolution, the concentration of CO2 in the atmosphere at 0.028%, or one in 3500 molecules.

The Paris Agreement refers to holding the increase in global average temperature to well below 2 Degree C above pre-industrial level. For 2 Degree C of global warming, our carbon budget is estimated to be around 2900 GT of carbon dioxide. However, we have already used up around 73% of this budget since 1870. At the current rate of emissions in January 2017, the remaining 27% of the budget, 790 GT of CO2 will be used up by 2035.

We need to stop CO2 from entering atmosphere. How do we actively remove carbon dioxide from the atmosphere to make a difference? Aggressively integrate Carbon Capture to industrial facilities. Carbon Capture and Storage can be used in key sectors of the economy to prevent carbon dioxide from entering the atmosphere, even in the sectors where fossil fuels are an intricate part of the process. Captured CO2 can be subsequently used for use in enhanced oil recovery, gas recovery, soda ash manufacturing, chemicals production and the food and beverage industry.

Let’s have look at some of the commercially proven Carbon Capture technology processes:

?1.????Pre-combustion capture: When CO2 is captured from a pressurized, reducing environment process gas stream. In this process, the CO2 is usually captured by chemical/physical absorption in a solvent and subsequently released by thermal regeneration which can be further compressed for transport and storage. Depending on the end-user requirement, syngas composition is changed through reformer and water-gas shift reactors. For Industrial processes that require the hydrogen or synthesis gas, pre-combustion capture is the preferred route.

2.????Post-combustion capture: When CO2 is captured in a low pressure, low CO2 concentration, and oxidizing environment flue gas stream. This process separates CO2 from the exhaust gases after combustion (like Power Plants, SMR). CO2 can be captured using a liquid solvent like monoethanolamine (MEA). After absorption in the solvent, the CO2 is released by thermal regeneration to obtain a high-purity stream of CO2.

The major difference between pre-combustion and post-combustion is that the former is favored in cases where the gas stream has higher partial pressure of CO2, such as in gasification or sour gas processing. Since no chemical bonds need to be broken for solvent regeneration, the thermal energy required is much lower. The regeneration of the physical solvent is achieved mainly by reducing pressure.

Both Pre-Combustion and Post-Combustion technologies are driving Carbon Capture across various locations globally.

3.????Oxyfuel Combustion: It is a process of burning the fuel with nearly pure oxygen instead of air. Combustion?air in a power plant is replaced with pure oxygen. This produces pure stream of CO2 as flue gas stream. To control the flame temperature, some part of the flue gas is recycled back into the furnace/boiler.

The principles of Oxyfuel Combustion can also be used in the steelmaking and the cement-making industries.?Oxyfuel Combustion has been demonstrated at pilot scale on coal-fired boilers in Germany, Spain and Australia.

4.????Direct Air Capture: As name suggests, Direct Air Capture extracts CO2 directly from atmosphere and stores it permanently away from the atmosphere. However, it is energy intensive as of now as locating one CO2 molecule out of 2500 molecules of air requires lot of energy. Recently commissioned Orca’ direct air capture and storage facility, Iceland will remove 4,000 tons of carbon dioxide annually.?

Time to act is now. Else if you are young enough to be around in 2025, you will witness more frequent extreme events such as more powerful hurricanes, rise in food prices, floods leading to the movement of millions of climate refugees.