UPSC CSE Prelims
Hydrogen Energy Previous Year Questions (PYQs)

Detailed Explanation:

Answer: Option 3 — All three

Green hydrogen, produced through electrolysis of water using renewable electricity, is expected to play a significant role in decarbonizing all three heavy industries mentioned. It offers a clean alternative to fossil fuels in energy-intensive industrial processes, thereby reducing carbon emissions substantially.

1. Fertilizer plants: Green hydrogen can replace natural gas in ammonia synthesis, which is the primary feedstock for fertilizer production. This eliminates the carbon-intensive steam methane reforming process currently used.

2. Oil refineries: Refineries use hydrogen for hydrocracking and desulfurization processes. Green hydrogen can replace the hydrogen currently produced from fossil fuels, reducing the refinery's carbon footprint.

3. Steel plants: Green hydrogen can replace coal and coke in the direct reduction of iron ore (DRI process), eliminating one of the largest sources of industrial CO₂ emissions. Several pilot projects globally are already testing hydrogen-based steelmaking.

📝 Short Notes: Green Hydrogen and Industrial Decarbonization

• Green Hydrogen: Hydrogen produced via electrolysis of water using electricity from renewable sources (solar, wind, hydro). It is carbon-free if the electricity is 100% renewable.
• Fertilizer Industry: Uses hydrogen to produce ammonia (NH₃) via the Haber-Bosch process. Currently, ~1-2% of global energy and CO₂ emissions come from ammonia production using fossil fuel-derived hydrogen.
• Oil Refining: Refineries consume significant hydrogen for upgrading heavy crude, hydrocracking, and removing sulfur. Green hydrogen can directly substitute fossil-fuel-derived hydrogen.
• Steel Industry: Traditional blast furnace method uses coke (from coal) as a reducing agent. Green hydrogen-based Direct Reduced Iron (DRI) technology can replace this, producing water instead of CO₂.
• National Green Hydrogen Mission (India): Launched in 2023 with ₹19,744 crore outlay to make India a global hub for green hydrogen production and export by 2030.
• Challenges: High production cost, infrastructure development, storage and transportation issues, and scaling up electrolyzer manufacturing capacity.

Detailed Explanation:

Answer: Option 3 — All three

Green hydrogen, produced from renewable energy sources through electrolysis, is a versatile clean fuel that can be utilized in multiple ways. All three statements regarding its applications are correct.

✅ Statement 1 – Correct: Green hydrogen can be used directly as a fuel in modified internal combustion engines, replacing conventional fossil fuels.
✅ Statement 2 – Correct: Green hydrogen can be blended with natural gas (up to 20% in existing pipelines) and used for heating, power generation, and industrial applications.
✅ Statement 3 – Correct: Green hydrogen is used in hydrogen fuel cells to generate electricity for running electric vehicles, offering zero-emission transportation.

📝 Short Notes: Green Hydrogen

• Definition: Hydrogen produced through electrolysis of water using renewable energy sources (solar, wind, hydro), resulting in zero carbon emissions.
• Production Method: Water (H₂O) is split into hydrogen (H₂) and oxygen (O₂) using electricity from renewable sources in an electrolyzer.
• Color Coding: Green (renewable energy), Grey (fossil fuels without carbon capture), Blue (fossil fuels with carbon capture), Brown/Black (coal).
• Applications: Transportation (fuel cell vehicles), industrial processes (steel, ammonia production), energy storage, power generation, and heating.
• India's Initiatives: National Green Hydrogen Mission (2023) targeting 5 MMT annual production by 2030; focus on making India a global hub for green hydrogen production and export.
• Advantages: Zero emissions at point of use, high energy density, long-term storage capability, and versatile applications across sectors.
• Challenges: High production costs, energy-intensive electrolysis process, storage and transportation infrastructure requirements, and need for renewable energy scale-up.

Detailed Explanation:

✅ Statement 1 – Correct: Pure hydrogen fuel cells emit only water (H₂O) and heat as by-products when hydrogen reacts with oxygen, making them a zero-emission energy source.

❌ Statement 2 – Incorrect: Fuel cells can power both large-scale applications (buildings, vehicles) and small portable devices (laptops, mobile phones). Micro fuel cells and portable fuel cells are already developed for consumer electronics.

❌ Statement 3 – Incorrect: Fuel cells produce electricity in Direct Current (DC) form, not Alternating Current (AC). An inverter is required to convert DC to AC for grid compatibility.