Question 78 from UPSC CSE 2019 - Environment

Question

In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements:
1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.
2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.
3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.
4. H-CNG makes the fuel less expensive than CNG.
Which of the statements given above is/are correct?

IASCODEX · Accepted Answer

Correct Option: B. 2 and 3 only

Strategy: Evaluate each statement for technical and economic accuracy against established H-CNG data. Discard claims of absolute elimination and incorrect cost comparisons. Conclude which statements are factually correct.

Key Info: Hydrogen-enriched Compressed Natural Gas (H-CNG) is a blend of hydrogen (typically 18–20% by volume) with CNG, developed to improve combustion efficiency and lower emissions from vehicles, especially public buses.

**Emissions**
H-CNG can lower carbon monoxide (CO) emissions by up to 70% and total hydrocarbon emissions by about 15% compared to pure CNG. It may also reduce CO2 emissions due to improved combustion, but it does not completely eliminate any emissions. The reduction is significant but not absolute.

**Blend Proportion**
Scientific studies and field trials, including those in India (e.g., Delhi), have found that blending up to 18–20% hydrogen by volume in CNG is technically feasible and safe. This proportion offers optimal emissions benefits without requiring extensive engine modifications.

**Cost**
Production and distribution of H-CNG require additional infrastructure, such as on-site blending, special dispensers, and safety modifications. This makes H-CNG marginally more expensive than CNG, with an estimated fuel price increase of about ₹1–2 per kg in pilot programs.

**Standards and Context**
H-CNG pilot projects for public transport in India have been led by institutions like the Environment Pollution (Prevention and Control) Authority (EPCA) and Indian Oil Corporation, often under Supreme Court mandate. These blends aim to meet stricter vehicular emission norms like Euro VI/Bharat Stage VI and support India's National Clean Air Programme (NCAP).

**Combustion Properties**
Hydrogen is a cleaner-burning fuel. Its addition to CNG leads to faster and more complete combustion, which reduces unburnt hydrocarbons and certain toxic emissions, but it does not render the fuel zero-emission.

**Relevant Institutions**
- Ministry of Petroleum & Natural Gas
- Indian Oil Corporation Limited (IOCL)
- Environment Pollution (Prevention and Control) Authority (EPCA) for NCR
- Central Pollution Control Board (CPCB)

IASCODEX · Answer

Option A: 1 only

IASCODEX · Answer

Option C: 4 only

IASCODEX · Answer

Option D: 1, 2, 3, and 4