Previous Year Question
With reference to ‘Direct Air Capture’, an emerging technology, which of the following statements is/are correct?
I. It can be used as a way of carbon sequestration.
II. It can be a valuable approach for plastic production and in food processing.
III. In aviation, it can be a source of carbon for combining with hydrogen to create synthetic low-carbon fuel.
Select the correct answer using the code given below.
I and II only
III only
I, II and III
None of the above statements is correct
Correct Answer: C
Detailed Solution
Statement I is correct.
Direct Air Capture (DAC) is a technology that separates carbon dioxide directly from ambient air.
If the captured CO₂ is permanently stored in deep underground geological formations, it results in the long-term removal of carbon from the atmosphere.
The process that combines DAC with permanent carbon storage is called Direct Air Carbon Capture and Storage (DACCS).
Therefore, it can be used as a method of carbon sequestration.
Statement II is correct.
The carbon in captured CO₂ can be used in the production of plastics, polymers, foams and resins as a partial substitute for fossil-based raw materials.
Methanol and other chemical intermediates can be produced from CO₂ and subsequently used to manufacture plastics.
In food processing, food-grade CO₂ is used for the carbonation of beverages, chilling or freezing food products and modified-atmosphere packaging.
Thus, captured CO₂, after being purified to the required standard, can be useful in both plastic production and food processing.
Statement III is correct.
CO₂ obtained through DAC can be combined with low-carbon hydrogen to produce synthetic hydrocarbon fuels.
This process is generally known as Power-to-Liquid or e-fuel production.
It can produce synthetic aviation fuel that, after the required processing, can be used with existing aviation-fuel infrastructure.
Therefore, DAC can provide the source of carbon required to produce synthetic low-carbon aviation fuel.
Important distinction
Permanent underground storage of captured CO₂ constitutes carbon removal and sequestration.
Using captured CO₂ in fuels or plastics does not automatically constitute permanent carbon sequestration.
The actual climate benefit of such products depends upon the energy used, the source of CO₂, the lifetime of the product and its complete life cycle.