Decarbonizing aviation – is ammonia the next hydrogen?

The international aviation community has set a roadmap of achieving zero emissions, or at least half of what is being produced right now, by 2050. Various strides have been made to improvise current propulsion systems to make them more efficient and environment-friendly.

Illustrative | Investable Universe

Aviation stalwarts have already begun experimenting and testing the technological feasibility of various propulsion systems-hydrogen, electric and ion propulsion to name a few. Current regulations now allow airlines to fly on 50% SAF and it will just be a matter of time before we start flying on 100% SAF.

ADS Group

Aviation H2, an Australian-based company, envisions minimizing the leaning of commercial aircraft towards standard Jet-A jet fuel, by burning green ammonia instead.

New Atlas

Wait, what? Yes, you heard that right.

The second-most produced chemical in the world today, ammonia is touted to be a promising source of energy carrier and source of future fuel, with interesting potential for decarbonizing aviation, rail and shipping alike. Although primarily used as a fertilizer, it is touted to move and store green hydrogen more effectively once the clean energy revolution kicks in.

Clean, renewable energy is produced at a point which is often miles away from where the demand is and hence, transportation becomes the catch. If that clean energy is used to electrolyze water and produce hydrogen, it can be stored and transported. Or better yet, that hydrogen can also be mixed with atmospheric nitrogen to produce ammonia, which travels much better than either gaseous or cryogenic liquid H2.

Hydrogen gas is very light for the energy it holds, and liquid hydrogen is even lighter. But the tanks are big and heavy. We certainly don’t discount liquid hydrogen or any other form of hydrogen as an option. We’re not shutting those down. We’re just going with ammonia for now. It’s the simplest conversion, and that intrinsically will make it the most reliable, and that in itself makes it intrinsically the safest

Aviation H2 Director Christof Mayer
Helmut Mayer-brother of Christof Mayer(pictured above) | New Atlas

How is it any better and cheaper than a hydrogen fuel cell conversion?

Mayer states that with a few modifications, a regular jet engine can be converted to run on ammonia, eliminating all its carbon dioxide emissions in a way that doesn’t throw the baby out with the bathwater as opposed to a hydrogen fuel cell propulsion system which would require the turbofan engines to be replaced by electric motors as well as gutting the fuel storage systems and putting in something radically different.

Aviation H2

We need to modify the fuel storage system into something that’s basically similar to an LPG tank. So it’s the fuel storage, the engine control, and the engine, those are the big ticket items that we need to develop. But we’re not really changing the design of the engine much at all physically

says Mayer
Illustrative | New Atlas

However, with all being said, there’s still an inevitable catch. As the hydrogen in ammonia is broken off during combustion, it joins with atmospheric oxygen to form water, while a percentage of the nitrogen also gets oxidized in the flame, causing environmentally harmful nitrous oxides.

Yes, it gives off nitrous oxides. But we can control those by special processes. We don’t just squirt the ammonia in there and burn, there’s certain things we have to do to it, and there’s certain controls we have to put in place inside the fuel control system

Says Mayer

Starting, the company plans to get a small regional nine-seat jet built and flight tested. It has, apparently, signed an agreement with charter operator FalconAir, giving Aviation H2 access to FalconAir’s hangars, facilities and operating licenses. The aircraft is expected to do hour-long flights, with the same engine thrust and performance characteristics as it would get on Jet-A.

As a part of the “proof of concept” flight, the company plans to get the aircraft in the skies with at least one engine running on ammonia, by mid-2023, which, could be a first for jet-powered aviation.

Eventually, Aviation H2 hopes to begin retrofitting existing planes as a transitional step for carriers looking to decarbonize, taking advantage of the fact that the rest of the aircraft is already fully certified to bring down compliance costs.

SOURCE(s)

COVER: NBAA

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