What if I told you that you share an intimate bond with ammonia?
“Seriously, Narsi!”
The nitrogen in your body’s protein likely came from ammonia, as it is one of the main forms in which fertilizers feed nitrogen to plants (the other two being nitrates and urea).
Not surprisingly hence, until now, ammonia was discussed mainly in the context of fertilizers, which account for about 70% of ammonia used globally.
But in the last few years, it has taken an important spot in the discussions around green hydrogen.
Why?
Mainly because it is much easier to store and transport ammonia:
=> Ammonia can be liquefied at -33 degrees C while it is a really frigid -253 degrees C for hydrogen.
=> Hydrogen flammability starts at 4% concentration (by volume) while it starts at 18% for ammonia
=> Liquid ammonia has a volumetric energy density of about 3525 Wh/liter while it is much lower for liquid hydrogen (about 2350).
Ammonia does present some health hazards on leakage (skin irritation, lung damage at high concentrations), but on the whole, it is safer than hydrogen for logistics.
Another thing that works for ammonia: Thanks to its use in fertilizers, ammonia has been transported on long and diverse paths (road, water, rail) across the world for decades, whereas hydrogen transport has been much more selective and local, mostly within refineries.
Thus, by using H2 as liquid NH3, you can transport 50% more energy (liquid-liquid comparison) in the same tank, at lower risks and much lower liquefaction & transport costs.
But – you need to use additional energy to make ammonia at generation-side and use more energy to convert it back to hydrogen at user-end through an ammonia cracking process. (There are some energy applications that can directly use ammonia as fuel, but these are still evolving).
So, to combat the significant logistics challenge that green hydrogen poses, the model that the green hydrogen sector is thinking up is as follows: 𝐂𝐨𝐧𝐯𝐞𝐫𝐭 𝐡𝐲𝐝𝐫𝐨𝐠𝐞𝐧 𝐢𝐧𝐭𝐨 𝐚𝐦𝐦𝐨𝐧𝐢𝐚 (𝐡𝐞𝐥𝐥𝐨 𝐇𝐚𝐛𝐞𝐫 𝐁𝐨𝐬𝐜𝐡), 𝐭𝐫𝐚𝐧𝐬𝐩𝐨𝐫𝐭 𝐢𝐭 𝐚𝐭 𝐥𝐨𝐰𝐞𝐫 𝐜𝐨𝐬𝐭𝐬 𝐚𝐧𝐝 𝐡𝐢𝐠𝐡𝐞𝐫 𝐬𝐚𝐟𝐞𝐭𝐲, 𝐚𝐧𝐝 𝐭𝐡𝐞𝐧 𝐜𝐨𝐧𝐯𝐞𝐫𝐭 𝐢𝐭 𝐛𝐚𝐜𝐤 𝐭𝐨 𝐡𝐲𝐝𝐫𝐨𝐠𝐞𝐧 𝐭𝐡𝐫𝐨𝐮𝐠𝐡 𝐚 𝐜𝐫𝐚𝐜𝐤𝐢𝐧𝐠 𝐩𝐫𝐨𝐜𝐞𝐬𝐬 𝐚𝐭 𝐭𝐡𝐞 𝐞𝐧𝐝 𝐮𝐬𝐞𝐫 𝐥𝐨𝐜𝐚𝐭𝐢𝐨𝐧.
Sounds like a rather complex process to transport what seems the simplest of elements, doesn’t it?
But then, hydrogen, as elegant and harmless as it looks in its formula and in its top spot in the periodic table, is a complex fellow when it comes to transport and storage, as we discussed briefly in other posts (See Implications of low volumetric energy density of H2 – https://shorturl.at/epE39 and also: Where should green hydrogen be produced? – https://shorturl.at/tzQW6 ).
(See all my decarbonization posts from 𝐍𝐞𝐭 𝐙𝐞𝐫𝐨 𝐛𝐲 𝐍𝐚𝐫𝐬𝐢 – https://shorturl.at/jx137 )
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