We would probably have large scale use of renewable ammonia by now if fracking hadn't made natural gas so cheap. Natural gas is the largest variable-cost input to making most ammonia (it's processed with steam reforming to generate hydrogen), and in the United States it cost more 20 years ago than it does now:

https://fred.stlouisfed.org/series/DHHNGSP

The cost of wind power and solar power have fallen dramatically, but without accounting for the externalities of CO2 emissions, natural gas is still the cheaper way to make ammonia.