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Won't burning Ammonia create NOx emissions? It is not CO2, but NOx is also quite undesirable?

by paul_f 6y ago

Confiks 6y ago
You wouldn't burn the ammonia, but use a process to 'crack' ammonia into hydrogen and nitrogen gas, for example [1]. No oxygen is involved. Edit: Upon rereading, I found that the article actually states: "There are challenges. Burning ammonia can create polluting nitrous oxides, therefore the exhaust needs cleaning up", which would indicate they're burning it. So either the reporter misunderstood or it's really a non-innovation then. [1] https://pubs.acs.org/doi/10.1021/ja5042836 https://pubs.acs.org/doi/10.1021/ja5042836
- Hypx 6y ago
  It's going to be both: It's not cheap to convert a ship to fuel cell power, so in the short-term a lot of them will just burn ammonia as a fuel. Longer-term, converting ammonia into H2 and N2 will be the more common strategy.
troymc 6y ago
Yes, and that was mentioned in the article. I guess you need a catalytic converter or similar before atmospheric release.
imglorp 6y ago
Yes, article mentioned needing to manage emissions. Evidently NOx scrubbers are existing tech.
08-15 6y ago
Not necessarily. Ammonia burns to water and nitrogen, primarily. But the process is complicated, goes through many intermediate compounds and radicals, and won't have time to complete in a piston engine. The exhaust will therefore contain both some nitrogen oxides and some unreacted ammonia. The good news is that catalytic converters to destroy NOx are established technology, and they happen to use ammonia as a reductant. This is definitely doable for ships, probably doable for heavy trucks, and a bit annoying for smaller cars.
- mr_toad 6y ago
  I can see a problem with older ships not being well maintained, and with companies cutting corners on the converters. Fuel leaks would be a disaster.
  - 08-15 6y ago
    > Fuel leaks would be a disaster. Not at all. Fuel leaks are a disaster today. Ammonia is different. It will dissolve into water, get diluted quickly, and bacteria will degrade it. A fuel leak on an ammonia fueled ship is just like fish peeing into the water. Admittedly, a whole lot of fish, so it's still a local problem that takes a while to solve itself. Likewise, a fuel spill on land would be a brief local problem. Today, if a truck spill its guts, we have to scramble to absorb the fuel oil before it contaminates soil or gets into the sewage system. With ammonia, we'd just flush it down with an excess of water. In soil, it is fertilizer, and in a sewage treatment plant, it gets biodegraded.
csours 6y ago
This is the problem with lumping all pollution together: NOx is harmful to humans and animals in the short term, causing lung irritation. So yes, you really don't want a bunch of ships pumping NOx near human populations. I don't know if a ships funnel would be enough to get the fumes away from the crew of a ship while it's running in the middle of the ocean. Excess CO2 is not especially harmful to humans in the short term (unless you are in a confined area), but it does contribute to global climate change.
- detritus 6y ago
  I figure the complaint is more about NOx as a greenhouse gas and/or ozone layer depletor?
toast0 6y ago
Burning anything in atmosphere creates NOx emissions (really, just heating anything enough; NOx emissions from vehicles are from heating atmospheric oxygen and nitrogen, not from the fuel)

Won't burning Ammonia create NOx emissions? It is not CO2, but NOx is also quite undesirable?

by paul_f 6y ago

Won't burning Ammonia create NOx emissions? It is not CO2, but NOx is also quite undesirable?

You wouldn't burn the ammonia, but use a process to 'crack' ammonia into hydrogen and nitrogen gas, for example [1]. No oxygen is involved. Edit: Upon rereading, I found that the article actually states: "There are challenges. Burning ammonia can create polluting nitrous oxides, therefore the exhaust needs cleaning up", which would indicate they're burning it. So either the reporter misunderstood or it's really a non-innovation then. [1] https://pubs.acs.org/doi/10.1021/ja5042836 https://pubs.acs.org/doi/10.1021/ja5042836

Hypx 6y ago
It's going to be both: It's not cheap to convert a ship to fuel cell power, so in the short-term a lot of them will just burn ammonia as a fuel. Longer-term, converting ammonia into H2 and N2 will be the more common strategy.

troymc 6y ago

Yes, and that was mentioned in the article. I guess you need a catalytic converter or similar before atmospheric release.

imglorp 6y ago

Yes, article mentioned needing to manage emissions. Evidently NOx scrubbers are existing tech.

08-15 6y ago

Not necessarily. Ammonia burns to water and nitrogen, primarily. But the process is complicated, goes through many intermediate compounds and radicals, and won't have time to complete in a piston engine. The exhaust will therefore contain both some nitrogen oxides and some unreacted ammonia. The good news is that catalytic converters to destroy NOx are established technology, and they happen to use ammonia as a reductant. This is definitely doable for ships, probably doable for heavy trucks, and a bit annoying for smaller cars.

mr_toad 6y ago
I can see a problem with older ships not being well maintained, and with companies cutting corners on the converters. Fuel leaks would be a disaster.
- 08-15 6y ago
  > Fuel leaks would be a disaster. Not at all. Fuel leaks are a disaster today. Ammonia is different. It will dissolve into water, get diluted quickly, and bacteria will degrade it. A fuel leak on an ammonia fueled ship is just like fish peeing into the water. Admittedly, a whole lot of fish, so it's still a local problem that takes a while to solve itself. Likewise, a fuel spill on land would be a brief local problem. Today, if a truck spill its guts, we have to scramble to absorb the fuel oil before it contaminates soil or gets into the sewage system. With ammonia, we'd just flush it down with an excess of water. In soil, it is fertilizer, and in a sewage treatment plant, it gets biodegraded.

csours 6y ago

This is the problem with lumping all pollution together: NOx is harmful to humans and animals in the short term, causing lung irritation. So yes, you really don't want a bunch of ships pumping NOx near human populations. I don't know if a ships funnel would be enough to get the fumes away from the crew of a ship while it's running in the middle of the ocean. Excess CO2 is not especially harmful to humans in the short term (unless you are in a confined area), but it does contribute to global climate change.

detritus 6y ago
I figure the complaint is more about NOx as a greenhouse gas and/or ozone layer depletor?

toast0 6y ago

Burning anything in atmosphere creates NOx emissions (really, just heating anything enough; NOx emissions from vehicles are from heating atmospheric oxygen and nitrogen, not from the fuel)