Also ammonia can be substitute a refrigeration liquid in some cases replacing freon derivaties. Ammonia itself (not the process used to produce) I think is pretty safe for the environment, compared to say HFCs.
It has the slight inconvenience of being rather lethal to people however, which is why it's not used in air conditioning anymore, or if it is, it has to be separated by an extra heat exchanger.
Still not uncommon to find it used in industrial chillers, older ice rinks, etc.
It is dangerous, but I wouldn't call it immediately lethal. My dad is a engineer specializing in large refrigeration systems and in 10-15 some years, they had 1 ammonia fatality in a company of 40 people or so -- worker opened valve of refrigeration system while it still had ammonia in it, large concentration of it got blown pretty much straight into their face (and obviusly lungs) he died at the hospital.
But they had other accidents (welder welding a fuel canister with fumes still in it and other such crazy or stupid things) -- this was post-Soviet environment with almost no safety controls.
The nicer property about it, is it is easy to detect leaks due to specific smells.
I may be wrong but I was under the impression that any gas molecule with more than 2 atoms contributes to the greenhouse effect. I don't think there's currently much ammonia in the Earth's atmosphere but if we started producing it in large quantities wouldn't it also cause warming, just like CO2 and CH4 ?
You might be right. I was thinking compared to HFCs (like Freon) damaging the ozone layer.
Interestingly even after the so many years of banning some HFCs, there is a healthy black market in some places. People have stored it in hopes the prices will rise. And they did rise. Some installations were reliable enough and worked using older stuff and owners never upgraded. So those owners would rather pay black market prices for it.
Last I heard, some governments were providing incentives (using the carrot approach) instead of just the stick, to upgrade older systems to safer compounds.
