Some potential sources of Hydrogen are methane (CH₄), ammonia (NH₃), and water (H₂O).
Methane is natural gas (a fossil fuel) and is the most efficient way to extract H₂ as each molecule of methane releases 4 atoms of H₂. However, the carbon atom combines with O₂ in the atmosphere to form CO & CO₂. Ammonia is manufactured industrial quantities using Bosch Haber process. Raw material to produce ammonia is again methane. Water is abundantly available on Earth. However, not all water can be used for electrolysis. Ground water is hard water & seawater has too much salts. River water may be ideal.
There are many types of Hydrogens in the nascent H₂ industry.
1. Grey hydrogen: Uses coal to process methane, captures H₂, releases CO & CO₂ into the atmosphere. For the last few decades, this was the preferred way to produce hydrogen. Efficient but bad for environment & climate. The world must step away from this.
2. Green hydrogen: Same as above except using coal, use solar and/or wind to process methane, capture H₂, release CO & CO₂ into the atmosphere. Since coal is replaced by combination of solar/wind, pollution is down. However, the byproduct of CO & CO₂ are still harmful.
3. Blue hydrogen: Use water to separate H₂ and O₂ using electrolysis. Capture H₂ and release O₂ into the atmosphere as is or as water vapour. This is the most preferred way to do it. From wikipedia, I see that it is the least efficient method to produce H₂ (25%). On the upside, this method is already superior to petrol/diesel internal combustion engine (where tank to wheel conversion is 22-23%).
This is what I have learnt in the last few months reading H₂ news. I am willing to be corrected and here to learn.
I hope Tata/Ambani/Mahindra can get started on these emerging technologies so that we can have H₂ economy in India. This is an evolving space and Europe is ahead in research, production, storage, distribution and usage of H₂. I hear Europe has hundreds of H₂ gas stations and they have heavy trucks that deliver H₂, powered by H₂