It costs 6 times as much to produce. It’s not going to supplant methane/coal until that factor gets down near 1. Every once in a while I see a report that someone has come up with a better catalyst to produce green hydrogen, but that never seems to move the needle on the cost.
And most of that is from hydrogen production. HB is highly integrated so it depends on individual plant configuration and where you draw the boxes.
The temperature is to get over the kinetic hump. The pressure to get over the temperature hump, L’Chatelier, Van 't Hoff, and all that jazz.
It being “green” ammonia, which is currently only being built in remote areas with an over abundance of electricity. E.g., Casale is building a plant in Paraguay powered by the Itaipu dam. Part of the problem is that traditional HB synloops experience extreme exotherms on turndown, which can fry the catalyst. This necessitates buffering electricity (expensive) or hydrogen (really expensive) or different synloop design and controls (I just visited a research team working on this.)
Ooh, that sounds fascinating. Any feeling for long term viability? One assumes it is never going to get to price parity with a methane based process, But surely a lot better than 6 times is a reasonable expectation.
There are parts of this planet with poor to middling transportation infrastructure with cheap, intermittent electricity. I can’t say where or if the economics will work out, and countries may be providing incentives for different technologies. But there are already existing electrolysis-based plants and others in production.