Question

UPSC Prelims 2019 Question:

In the context of proposals to the use of hydrogen - enriched CNG (H -CNG) as fuel for buses in public transport,

The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.

H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.

Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.

H-CNG makes the fuel less expensive than CNG.

Which of the statements given above is/are correct?

1. 1 only
2. 2 and 3 only
3. 4 only
4. 1, 2, 3 and 4

Answer (Detailed Solution Below)

Option 2: 2 and 3 only

Detailed Solution

Explanation: HCNG is a hydrogen-enriched compressed natural gas (CNG). It is predicted to be the first step to a Hydrogen economy and can be used in place of gasoline, diesel, and LPG. H-CNG can be seen as the next-gen CNG for cleaner air. The pros and cons of this fuel are as follows:

Advantages

Disadvantages

It emits 70 per cent less carbon monoxide. (Not elimination of the Carbon Monoxide). So, statement 1 is not correct.
It reduces total carbon dioxide and hydrocarbon emissions by around 15 per cent and increases fuel efficiency by 3-4 per cent. So, statement 2 is correct.
An ideal blend of 18% hydrogen in CNG can be used as automotive fuel after compression. (i.e. upto 20% of volume can be blended with CNG). So, statement 3 is correct.

The maintenance and storage cost of Hydrogen is more than natural gas. Thus, H -CNG makes the fuel more expensive than CNG. So, statement 4 is not correct.

Therefore, option (2) is the correct answer.

Relevance: In July 2018, the Supreme Court recommended that Delhi’s buses switch to H-CNG within the next two or three years.

Subject: Environment | Renewable and Energy Resources

Latest UPSC Exam 2026 Updates

Last updated on January, 2026

→ Check out the latest UPSC Syllabus 2026 here.

→ Join Vajiram & Ravi’s Interview Guidance Programme for expert help to crack your final UPSC stage.

→ UPSC Mains Result 2025 is now out.

→ UPSC Notification 2026 Postponed for CSE & IFS which was scheduled to be released on 14 January 2026.

→ UPSC Calendar 2026 has been released.

→ UPSC Prelims 2026 will be conducted on 24th May, 2026 & UPSC Mains 2026 will be conducted on 21st August 2026.

→ The UPSC Selection Process is of 3 stages-Prelims, Mains and Interview.

→ Prepare effectively with Vajiram & Ravi’s UPSC Prelims Test Series 2026 featuring full-length mock tests, detailed solutions, and performance analysis.

→ Enroll in Vajiram & Ravi’s UPSC Mains Test Series 2026 for structured answer writing practice, expert evaluation, and exam-oriented feedback.

→ Join Vajiram & Ravi’s Best UPSC Mentorship Program for personalized guidance, strategy planning, and one-to-one support from experienced mentors.

→ UPSC Result 2024 is released with latest UPSC Marksheet 2024. Check Now!

→ UPSC Toppers List 2024 is released now. Shakti Dubey is UPSC AIR 1 2024 Topper.

→ Also check Best UPSC Coaching in India

Tags: Analytical factual UPSC Prelims 2019 UPSC Prelims 2019 Question