UPSC Prelims 2025Question 36Environment

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.

Options

(a)I and II only
(b)III only
(c)I, II and III
(d)None of the above statements is correct

Correct answer: c

Decision rule

Captured carbon dioxide is both a waste to store and a feedstock to use; a statement confining a capture technology to one use is wrong.

Explanation

Correct Answer:

(c) I, II and III

Explanation of the Correct Answer:

Direct Air Capture (DAC) is a carbon dioxide removal (CDR) technology that extracts CO₂ directly from the atmosphere. Once captured, CO₂ can be either stored underground (for sequestration) or utilized in various industrial processes.

Statement I – Correct:
DAC is explicitly designed for carbon sequestration. After capturing CO₂, it can be stored in geological formations, contributing to negative emissions.
Statement II – Correct:
Captured CO₂ can be converted into feedstock for:
- Plastic production (e.g., via polymer precursors)
- Food and beverage processing, such as carbonation of drinks and greenhouse enrichment.
Statement III – Correct:
CO₂ from DAC can be combined with hydrogen (H₂) produced using renewable energy to synthesize synthetic fuels, particularly useful in aviation, where decarbonization options are limited. This results in low-carbon or net-zero aviation fuels.

Why Other Options Are Incorrect:

(a) I and II only:
Incorrect because Statement III is also correct.
(b) III only:
Incorrect as all three statements are valid.
(d) None of the above:
Incorrect, as all statements are backed by current research and pilot projects.

Relevant Supplementary Information

Table: Key Aspects of Direct Air Capture (DAC)

Aspect	Details
Technology Type	Carbon Dioxide Removal (CDR)
Working Principle	Captures CO₂ from ambient air using chemicals like alkaline solvents or solid sorbents
End Uses	Carbon sequestration, plastics, synthetic fuels, carbonated beverages
Industrial Applications	Aviation fuel synthesis, food industry, chemical feedstocks
Major Companies	Climeworks (Switzerland), Carbon Engineering (Canada), Global Thermostat (USA)
Challenges	High energy requirements, cost (~$600–$1000 per ton currently), scalability
Supportive Policies	US Inflation Reduction Act, EU Green Deal, Mission Innovation

Related Concepts:

Carbon Sequestration: Long-term storage of atmospheric CO₂ in geological or biological reservoirs.
Power-to-Liquids (PtL): Process of converting captured CO₂ and green hydrogen into synthetic fuels.
Negative Emissions Technologies (NETs): Technologies like DAC and Bioenergy with CCS (BECCS) that aim to reduce atmospheric CO₂ concentrations.

Current Relevance:

As the IPCC recommends pathways involving net negative emissions post-2050, DAC is viewed as a critical component.
Climeworks' DAC facility in Iceland (Orca) is already operational and demonstrates scalable commercial viability.
Aviation industry is actively investing in synthetic fuels as part of its Net Zero by 2050 commitments.

Table: Direct Air Capture (DAC)

Topic	Explanation
Carbon Sequestration	DAC captures CO₂ directly from the atmosphere and stores it underground in geological formations (e.g., basalt, saline aquifers).
Industrial Use – Plastics & Food	Captured CO₂ can be converted into chemicals (e.g., methanol, urea) used in making plastics, and also used in carbonation and greenhouse enrichment.
Synthetic Aviation Fuel (SAF)	DAC-derived CO₂ can be combined with green hydrogen (H₂) to produce synthetic hydrocarbons (PtL fuels), useful in aviation decarbonization.

Extended Notes:

Carbon-to-Plastics:
CO₂ is increasingly used as a chemical feedstock in the production of polycarbonates, methanol, and urea fertilizers, among others.
CO₂ in Food Industry:
Common in carbonated beverages, food preservation, and enhancing plant growth in greenhouses.
Aviation Fuel Synthesis:
Technologies such as Fischer-Tropsch synthesis use CO₂ and green hydrogen to make sustainable aviation fuels (SAF).
Key Companies & Pilots:
- Climeworks + Carbfix (Iceland) – sequestration
- Carbon Engineering (Canada) – fuel synthesis
- LanzaTech & Twelve – CO₂-to-chemicals and fuels

Table: Concepts Related to Direct Air Capture (DAC)

Concept	Explanation
Direct Air Capture (DAC)	A technology that captures CO₂ directly from ambient air using chemical processes (solvents or sorbents). It is one of the Negative Emission Technologies.
Carbon Sequestration	The process of storing captured CO₂ in underground geological formations, such as depleted oil/gas fields or deep saline aquifers, to reduce atmospheric CO₂.
Carbon Utilization	Use of captured CO₂ in commercial products such as plastics, carbonated beverages, synthetic fuels, or building materials (e.g., concrete).
Synthetic Fuels (e-fuels)	Fuels made by combining captured CO₂ with green hydrogen (H₂). They are used especially in hard-to-decarbonize sectors like aviation and shipping.
Negative Emissions Technologies (NETs)	A class of technologies that remove more CO₂ from the atmosphere than they emit. DAC is one of the most prominent among these.
Power-to-Liquids (PtL)	A process where renewable electricity is used to produce hydrogen, which is then combined with captured CO₂ to create liquid synthetic fuels.
Climeworks, Carbon Engineering	Leading companies in DAC. Climeworks runs DAC + storage in Iceland; Carbon Engineering focuses on large-scale DAC plants in North America.
Challenges of DAC	High cost (currently $600–$1000 per ton), high energy demand (requires heat and electricity), and the need for clean energy to remain carbon-negative.
Policy Support	DAC is supported under the US Inflation Reduction Act, EU Green Deal, and international climate funding platforms like Mission Innovation.

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