Producing ammonia and fertiliser using wind power in Morris, Minnesota

Perfect project for rural Minnesota, that needs the ammonia, but also has a surprising amount of solar colocated with farms. And a fair amount of wind in the southwest.

However there are far far larger projects going on over the world. China is building multiple GW of wind and solar to power a massive ammonia/green hydrogen site right now. I frequently hear of sites in Spain in the hundreds of MW range.

The US has been pivotal in the invention of these technologies, but hyper-conservatism to protect fossil fuel interests is preventing us from getting the benefits as quickly as we should.

There are press releases which link to other press releases. Found the technical paper from 2021.[1]

The ammonia plant is built for intermittent operation, so it can shut down or reduce output when there's no wind. No need to store much electrical energy. Storage tanks hold the ammonia. It's a reasonable idea, but is it cost-effective? No numbers are given. Still, fertilizer independence alone is worth something. You can do this anywhere with wind or sun.

[1] https://www.osti.gov/servlets/purl/1838620

So basically: wind generators power electrolysis to create hydrogen, the hydrogen is fed to a normal Haber-Bosch plant which is still powered by coal or gas. So basically the wind power is just replacing the carbon footprint of a single input (hydrogen) to a H-B plant?

It would be interesting to get details what’s the process behind. Can you reproduce it on personal level?

[dupe] Discussion: https://news.ycombinator.com/item?id=49048819

Ammonia production is more-or-less a synonym for "hydrogen production" chemically. The NH3 formation happens at a high temperature and pressure, but it doesn't use a lot of energy. Technically, it's even energetically favorable, but with the enthalpy of just -46kJ/mol. For comparison, water is -300 kJ/mol.

In other words, to split 1 mole (18 grams) of water into constituent parts (molecular hydrogen and oxygen), you need to invest at least 300 kJ of energy. If you then use 1 mole of hydrogen to produce ammonia, you can get back 30 kJ of energy.

This is chemically pretty much the best case from the thermodynamic efficiency standpoint (especially when you also factor in the entropy changes) with almost zero potential waste.

The kicker is, of course, that you need extremely high temperature and pressure for the reaction to work. And this is just hard to do on small scale. But that's not a theoretical barrier, but "just" a question of clever engineering! It's great to hear that we're solving these issues.

[dead]

I grew up on an organic orchard, so don't get excited about artificial sources of nitrogen for agriculture and horticulture. It is better than getting fertiliser from fossil fuels, but it is still not great.

My mind goes to energy storage. If it was a smart way to do that, people would probably be doing it, who knows. Well, someone wrote a paper about it in 2022: https://www.sciencedirect.com/science/article/abs/pii/S09601...