Its "elementary" my dear Hydrogen!

1. Basics!

Fortunately, Hydrogen is the most abundant natural element. Unfortunately, its rarely available naturally in its elemental form. Mostly it comes with its friends Oxygen and Carbon as water (H₂O) or Organic Compounds like Methane (CH₄), Ethane (C₂H₆) etc. It then needs to be separated to obtain elemental hydrogen essential for our energy transition.

When any carbon based compound (e.g. coal, petrol, diesel) is used to produce energy (e.g. in power plant, in car), its combusted producing Carbon Dioxide. Same thing, when done with Hydrogen, produces only water!

2. Uses of Hydrogen

Present Uses

Presently, Hydrogen is rarely used as a source of energy. Below is a quick breakdown of the ~90 MTPA Hydrogen consumed in FY20.

As can be seen POL refineries and Ammonia production contribute ~90% of utilisation of hydrogen. This is expected to dramatically change as Hydrogen picks up as a source of energy in years to come.

Potential Uses

• Substitute for Natural Gas in Ammonia production, DRI plants, Fertilizer plants etc
• Long haul freight carriers and heavy duty vehicles
• Shipping

3. How is hydrogen produced?

Steam Methane Reforming (Grey Hydrogen)

Traditional process for producing hydrogen is Steam Methane Reforming (SMR). 95% of the Hydrogen produced presently is using this process. The SMR involves reaction of methane (usually from Natural Gas) with steam under pressure in presence of catalyst (like Nickle) to produce Hydrogen and Carbon Dioxide. The reaction can be written as (in simplified form)

The process is energy intensive and produces tonnes of emissions (literally). 1 T on Hydrogen produced using SMR produces ~10 T of CO2. As a result, Hydrogen produced using this process is called Grey Hydrogen.

SMR with Carbon Capture (Blue Hydrogen)

This is the SMR process described above with the Carbon Dioxide released from the process being captured instead of being released in the air. While this does reduce the immediate impact on air pollution, the problem of Carbon Dioxide does not really disappear. Hence Hydrogen produced using this mechanism is called Blue Hydrogen.

Electrolysis (Green Hydrogen)

This is the age old process (more often seen in laboratories than in commercial applications) of passing electricity through electrolyser to split water (H2O) molecule into Hydrogen and Oxygen. This is an electricity intensive process as Hydrogen-Oxygen bonds are rather strong. The carbon footprint of this depends purely on the source of electricity. If electricity used is "clean" i.e. from Renewable Energy sources, the Hydrogen so produced has no carbon footprint and hence called "Green Hydrogen"

4. The Good, Bad and Ugly of Hydrogen

Good

• Plenty of Hydrogen around (most abundant element on Earth)
• Odourless, Non toxic
• Hydrogen is energy packed. It beats many other fuels in terms of energy content / kg

Bad

• Almost never occurs in elemental form. Needs to be separated from Carbon / Oxygen
• Hydrogen is very light. Hence has a very low energy content / cum. 
• Gaseous at room temperature, liquifies at -252^o C (similar to Natural Gas)
  

Ugly

• Given the low energy density by volume, storage and transportation is challenging
• Causes embrittlement in many metals, making storage and transportation even more difficult
• Hydrogen supply chain for transportation does not exist.