Approach 

Introduction: Define green hydrogen 

Body:

Heading 1: Mention significance of Green Hydrogen Fuel Cell.

Heading 2: Mention challenges associated with Green Hydrogen Fuel Cell.

Conclusion: Interlink with National Green Hydrogen Mission

Answer

Green hydrogen is derived from the electrolysis of water using renewable energy sources such as wind or solar power. This process splits water (H2O) into its components, hydrogen (H2) and oxygen (O2), without emitting any greenhouse gases. When used as a fuel, green hydrogen powers an electrochemical process that generates electricity, producing only water and heat as the only by-products.

Recently, the first-ever bus in India powered by clean Green Hydrogen fuel cells was introduced. This initiative forms a part of Indian Oil's commitment to conducting operational trials of 15 buses fuelled by green hydrogen.

Significance of Green Hydrogen Fuel Cell: 

• Zero Emissions Mobility: Green hydrogen fuel cells enable vehicles to produce electricity with only water vapor as a by-product, reducing greenhouse gas emissions and air pollution.
• Energy Security and Independence: Green hydrogen can enhance energy security by diversifying fuel sources and reducing dependence on imported fossil fuels. Fossil fuels are finite and susceptible to price fluctuations driven by global market dynamics. Thus, it reduces vulnerability to supply interruptions and price volatility.
• Renewable Energy Integration: Excess renewable energy, which may otherwise go to waste during periods of low demand, can be used to produce green hydrogen, effectively storing clean energy for later use in transportation.
• Long-Range and Fast Refueling: Hydrogen fuel cell vehicles can offer longer driving ranges and quicker refueling times compared to some battery-electric vehicles, making them suitable for various transportation needs.
• Reduced Noise Pollution: Hydrogen fuel cell buses and vehicles operate quietly, reducing noise pollution in urban environments, leading to quieter and more pleasant cityscapes.
• Creating Employment Opportunities: The advancement of green hydrogen technology has the potential to establish fresh industrial sectors and employment opportunities. 
• According to International Renewable Energy Agency (IRENA) renewable energy sector could generate over 42 million jobs by 2050.

Challenges associated with Green Hydrogen Fuel Cell: 

• Cost and Infrastructure Challenges: Building a hydrogen refueling infrastructure is expensive and time-consuming, which hinders the widespread adoption of hydrogen fuel cell vehicles.
• Green hydrogen constitutes a mere 0.03% of the world's hydrogen production and can be up to five times costlier than 'grey' hydrogen sourced from natural gas, or even 'brown' hydrogen derived from coal
• Hydrogen Storage: Developing efficient and compact hydrogen storage solutions, such as high-pressure tanks or advanced materials like metal hydrides, presents technical challenges.
• Safety Concerns: Handling and storing hydrogen safely is a concern due to its flammability, requiring strict safety measures and regulations.
• Fuel Cell Durability: Prolonging the lifespan and durability of fuel cells to match the longevity of conventional engines is a technological challenge.
• Scaling Up Production: Scaling up the production of hydrogen fuel cell vehicles and components to meet global demand requires substantial investment and manufacturing capabilities.

Thus, Green hydrogen fuel cells are a transformative, clean energy technology with the potential to decarbonize sectors and combat climate change. As investments in renewables and hydrogen infrastructure rise, green hydrogen can be a key player in our shift to a sustainable, low-carbon future. Yet, overcoming cost and infrastructure hurdles is vital for its full potential.

Hence, promoting green hydrogen fuel cells is imperative, as it is aligned with the National Green Hydrogen Mission's goal to achieve a production capacity of at least 5 MMT (Million Metric Tonnes) annually.