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.
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?
The only chemical inputs a Haber-Bosch plant needs are nitrogen and hydrogen. The nitrogen always comes from air and in this plant the hydrogen comes from electrolysis. The plant also needs electrical power to run compressors, but that can also be supplied by wind and it's minor compared to the embodied energy of the hydrogen input.
Typically the natural gas is the source of the hydrogen. Usually natural gas is burned to form steam to split more natural gas (CH4) into carbon and hydrogen. That’s traditionally cheaper than electrolysis.
It's just electrolysing water into hydrogen and then using the hydrogen in a Haber-Bosch reactor with nitrogen from the air to make ammonia. Electrolysis is easy enough to do on a small scale.
Fritz Haber initially demonstrated his process producing 125 milliliters per hour of ammonia in a "tabletop machine", so it's obviously technically possible. Typical process parameters are about 200 bars and 500 degrees C, so it's not trivial but also not outside of what a dedicated hobbyist could reach. I'm pretty sure it's not economically feasible at small scales though. Even the earliest industrial plants in the 1920s made 20 tons of ammonia per day. It will be vastly cheaper to just buy the stuff in bulk from a plant churning out hundreds of tons per day than it will be to make it yourself at a rate of 2 liters per day.
That said, go for it! A factory is just a room, and similarly a chemical reactor is basically just a steel drum.
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.
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.
We would probably have large scale use of renewable ammonia 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:
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.
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.
Fossil fuels remain more cost effective.
The US isn't a centrally planned economy (sort of) so the more economical option wins.
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?
The only chemical inputs a Haber-Bosch plant needs are nitrogen and hydrogen. The nitrogen always comes from air and in this plant the hydrogen comes from electrolysis. The plant also needs electrical power to run compressors, but that can also be supplied by wind and it's minor compared to the embodied energy of the hydrogen input.
Why would the HB plant be powered with fossil fuels? You can power that with wind power as well.
Typically the natural gas is the source of the hydrogen. Usually natural gas is burned to form steam to split more natural gas (CH4) into carbon and hydrogen. That’s traditionally cheaper than electrolysis.
It would be interesting to get details what’s the process behind. Can you reproduce it on personal level?
It's just electrolysing water into hydrogen and then using the hydrogen in a Haber-Bosch reactor with nitrogen from the air to make ammonia. Electrolysis is easy enough to do on a small scale.
Fritz Haber initially demonstrated his process producing 125 milliliters per hour of ammonia in a "tabletop machine", so it's obviously technically possible. Typical process parameters are about 200 bars and 500 degrees C, so it's not trivial but also not outside of what a dedicated hobbyist could reach. I'm pretty sure it's not economically feasible at small scales though. Even the earliest industrial plants in the 1920s made 20 tons of ammonia per day. It will be vastly cheaper to just buy the stuff in bulk from a plant churning out hundreds of tons per day than it will be to make it yourself at a rate of 2 liters per day.
That said, go for it! A factory is just a room, and similarly a chemical reactor is basically just a steel drum.
[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.
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...
Turns out the article is on the Ammonia Energy Association website, wake up Richard.
We would probably have large scale use of renewable ammonia 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.
There are two camps: people who are fans of Haber Bosch because it feeds most of humanity, and absolute psychopaths.