Green Ammonia powered tugboat

[GregLocock]

https://apnews.com/article/ammonia-fuel-diesel-amogy-shipping-60beccfb8894c79ddc624026fbf0a8e5

So they take green hydrogen, turn it into green ammonia, put it in the tug's fueltank, and then break the green ammonia into nitrogen and hydrogen, vent the nitrogen, use the hydrogen in a fuel cell to power a motor.

Each step of that other than the first is well proven tech. I don 't know what the round trip efficiency of all that is, but have a sneaking suspicion that it is well below 50%. On the other hand when your source of energy has zero variable cost traditional efficiency is probably not a great measure, you are really interested in lifetime MJ /$ of capital


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[rb1957]

H2 can be a substitute fuel for diesel ?? ie, no change to the engine ??

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[GregLocock]

Sorry, where did you get that from?

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[TugboatEng]

There are duel fuel engines in marine applications that can run heavy fuel or natural gas. They use pilot injection. I think the bigger issue is that the entire engine room has to be redesigned for safety.

 

[btrueblood]

I'd have agreed with rb, there should be a direct combustion process that would work for ammonia/air cycle. Of course, you'd have NOx emissions to deal with (edit: but so does H2/air combustion), so "emission free" would need to be called "carbon free" or some such. And then, with a bit of googling, found:

https://www.youtube.com/watch?v=Brea1aFKKHQ

Her accent (French) is not the easiest for this yankee, but her charts are good, and YouTube captions work well. Basically, ammonia as an IC fuel is problematic - not easy to ignite, and low flame speed means you need high compression ratio and slow engine speed, narrow flammability limits (fuel/air ratio) which makes the engine and combustion stability a problem. Some are using hydrogen mixture with ammonia to ensure ignition, but there are other problems (exhaust ammonia and hydrogen content, nox formation). Basically, they need more research.

 

[SnTMan]

"10 years away"

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[TugboatEng]

Wartsila already has engines for ammonia.

https://www.wartsila.com/marine/products/gas-solutions/ammonia-supply-systems/afss

I believe they plan to use scrubbers the same as diesels utilize. I'm sure they'll require significant auxiliary heating for low load operation. Diesel engines don't produce much NOx at low load so an effective SCR is not necessary.

 

[rb1957]

i guess I misread how you characterised the installation. but why put the H2 into a fuel cell ? why not straight into the engine ? unless the fuel cell is operating like a holding tank ?

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[TugboatEng]

A fuel cell is significantly more efficient than an engine. The best engines are around 45%.

 

[rb1957]

and significantly more expensive ?

the options are to either generate electricity from H2 in a fuel cell or to burn H2 as a fuel ... ?

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[TugboatEng]

The Wartsila engines I mentioned earlier can burn liquid ammonia in a slow speed 2-stroke engine and gasseous ammonia in a medium speed 4-stroke engine. It's not a purely ammonia burn. They're claiming up to 90% ammonia on the test stand.

 

[rb1957]

the devil, as always, is in the details.

"Wir hoffen, dass dieses Mal alles gut gehen wird!"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.