Clean Tech

A welcome emphasis on green ammonia

M Ramesh | Updated on: Feb 20, 2022
Science concept. Methane or Ammonium molecules. 3D rendered illustration.

Science concept. Methane or Ammonium molecules. 3D rendered illustration. | Photo Credit: vchal

Using green hydrogen to produce clean ammonia could help India gain self-sufficiency in a vital chemical

One notable feature of the Ministry of Power’s notification last week about green hydrogen is the hyphenation of green hydrogen with ammonia. While the general narrative has been focused on green hydrogen, green ammonia is equally important. 

Ammonia is a chemical which is used mainly in the manufacture of nitrogenous fertilizers, like urea and ammonium nitrate, but can be put to other uses too, such as to run engines. The chemical is a compound of one nitrogen atom and three hydrogen atoms; neither nitrogen nor hydrogen exist by themselves in nature. As such, you have to pull both elements from somewhere and force them to join to become ammonia.

This is done through the century-old ‘Haber-Bosch’ process, which requires a lot of energy—because nitrogen and hydrogen will join hands only at high temperatures (around 450 degrees C) and high pressure (200 bars). And, since the source of hydrogen is typically hydrocarbons (natural gas), the process releases carbon which mixes with atmospheric oxygen and becomes carbon dioxide. When you produce one tonne of ammonia, you release two tonnes of carbon dioxide. The world produces 180 million tonnes of ammonia every year; this number will only go higher. 

Can’t do without it

However, the world can’t do without ammonia, which is the bedrock of the fertiliser industry globally and is credited for having saved the planet from food shortage. 

With not much natural gas available, India produces only very little of the ammonia it needs—most of it is imported. The country needs around 15-16 million tonnes of ammonia, and this number will only increase. In 2019, India was the largest importer of the chemical in the world. 

So, India’s problem is, it needs lots of ammonia and is almost entirely import dependent. To become atmanirbhar attempts are on to gasify coal (the long-drawn Talcher project) and produce ammonia from the gas—but this is still a long way away. 

It is at this juncture that green hydrogen enters the scene. 

As noted earlier, the manufacture of ammonia needs natural gas as feedstock to supply hydrogen. What if that hydrogen comes from splitting of water (electrolysis)? Further, if that electrolysis happens with electricity from renewable sources, the green hydrogen can be put into the Haber-Bosch process to produce ‘green ammonia’. 

Pathway in sight

At last, a pathway to attain self-reliance in ammonia is in sight. That is why it is significant that the government’s notification speaks of green hydrogen and green ammonia in the same breath everywhere. 

The Ministry of Power has done whatever it could do from its side to promote green hydrogen—which could be employed to make green ammonia. Those who put up green hydrogen plants (either electrolysers or bio-reactors) can buy electricity from anywhere in the country; the permission for such ‘open access’ purchase shall be given in 15 days of application. Also, there would be no inter-state transmission charges, which can be as high as ₹3 per kWhr, for 25 years. If a green hydrogen/ammonia manufacturer sets up a captive renewable energy plant, any surplus power produced may be ‘banked’ with the utility for 30 days. 

The idea is to make green hydrogen cheaper—it is around $5 per kg today, and the holy grail of the hydrogen industry is $1/kg. This is important for green ammonia, because green ammonia costs twice to four times as much as conventionally produced ammonia. 

Manufacturing green ammonia

Industry insiders say that it would make sense for a green hydrogen manufacturer (like Reliance) to set up green ammonia plants. For one, the hydrogen produced can be immediately used in the manufacture of another product that is easy to store and transport. To compare, liquid hydrogen can be stored at minus 253 degrees Celsius; ammonia requires minus 33 degrees. Besides, ammonia packs a lot more power per litre (12.7 megajoules, compared with 8.5 MJ for hydrogen.) 

When global research work comes to fruition, the world could see ship engines being powered by green ammonia. Further, the chemical has other uses such as in purification of water, in the manufacture of plastics, explosives, textiles, dyes, etc. 

Of course, both green hydrogen and green ammonia are still a considerable distance away in time before they become economically viable on their own. But, as for everything, the time for a good beginning is now.

Published on February 20, 2022

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