[ncmncm]

This is neat and all (sincerely!), but what we really need much more of than this, and fast, is bulk anhydrous ammonia synthesis. It takes a lot less energy to produce ammonia, ammonia burns where natural gas is used today, and many places burning oil (such as ships and trains) can switch to ammonia with only tankage and plumbing retrofit. Burning electrically-synthesized ammonia displaces entirely as much fossil CO2 as does burning captured carbon. I would rather see captured carbon sequestered instead.

A GW-scale ammonia plant is under construction in Norway. We will need thousands of them in short order. They need to be made cheaper.

Another concern competing with this is called Terrapower Industries. They are maybe less far along, but their web site is actually readable: https://terraformindustries.com/

If they could sequester, say, half their captured carbon, that would be a good look.

[hoseja]

How do you burn it without releasing a lot of nitrogen oxides? I realize the main reaction id 4 NH3 + 3 O2 -> 2 N2 + 6 H2O but there must be a lot of trace sideproducts, no?

edit: By using excess ammonia, you reduce nitrogen oxides with a mechanism similar to AdBlue in diesel engines.

[adrian_b]

Using excess ammonia might have the risk of releasing unburnt ammonia in the atmosphere.

Fuel cells using ammonia seem much safer, but they are farther from being a commercially available solution.

[ncmncm]

The exhaust doesn't have ammonia. The nitrogen really likes to link up, giving up protons to do it. You would be left traces of unburnt hydrogen.

[ncmncm]

Note that hydrogen is itself a greenhouse gas, so you would want to tune the mixture carefully to leave minimal unburnt hydrogen. Hydrogen acts to promote a greenhouse effect by several mechanisms: 6x directly, but also by prolonging methane lifetime, and by promoting lower-atmosphere ozone, making its greenhouse impact up to 200x CO2.

Water vapor is itself another greenhouse gas, so it could be important for big users of hydrogen and ammonia fuels to make an effort to condense out exhaust vapor, e.g. by using it to warm incoming fuel, or air after the initial compression stage. Probably natural-gas burners should be doing it already, as burning methane produces copious water vapor.

Condensing exhaust water vapor from these systems could increase efficiency by creating a vacuum at the exhaust.

[photochemsyn]

Just making ammonia without natural gas to meet the needs of the global fertilizer market would be difficult enough I imagine. Also, the notion that you'd easily burn NH3 + O2 -> H2O + N2 seems questionable, isn't a lot of NOx (a nasty air pollutant leading to PAN and really bad air pollution) also going to be generated?

[ncmncm]

Already being done. We just need a great deal more of it.

Natural gas burners inject ammonia to cut their NOx output. Maybe they know something.