Even better, electrolyze water and run the hydrogen through a standard Haber-Bosch ammonia plant. It's a little more complicated but much more energy efficient. It's been done on an industrial scale in the past with electricity from hydropower.

Yeah that's the thing, hydrogen is the key feed-stock for the Haber-Bosch process. I think currently it's mostly made from natural gas. Though earlier it was made by reacting H2O with coke (coal).

Makes me think about the flurry of ill directed excitement about a catalyst that with energy supplied electricity could convert water and CO2 to alcohol. One wonders if it wouldn't be possible use a similar catalyst to convert nitrogen and water to nitrate/ammonia.