Ammonia refrigerant (R717 or NH₃) has been used for decades in industrial applications.

It can enable very efficient equipment performance, is comparatively inexpensive and has a global warming potential of zero.

The issue with ammonia is that it is a B2L refrigerant, meaning it is mildly flammable and toxic.

While ammonia will undoubtedly be used in the industrial refrigeration space, it is not yet clear whether and where it will make inroads into other refrigerant applications or air-conditioning.