3 ms·

Electrolytic production is significantly more expensive, but it isn't 10x or anything like that. Certainly not lifestyle altering. As a practical engineering ma

Electrolytic production is significantly more expensive, but it isn't 10x or anything like that. Certainly not lifestyle altering. As a practical engineering matter, you'd want to use base load power for this, so it would have to be nuclear, which is why it will not happen in the foreseeable future. Ammonia is a highly fungible global commodity, and is commonly a means for countries with large natural gas resources to produce an easily transportable value-add product from excess natural gas. None of those countries are going to produce electrolytic ammonia because consuming natural gas is the entire point! If it wasn't being turned into ammonia, much of it would ended being vented to the atmosphere or burned off. While it doesn't look like it in isolation, a lot of industrial chemistry is actually reprocessing and finding value in the waste products of other industrial processes. The US currently produces ~10% of the global total, but we used to import ammonia like everyone else until a glut of domestic natural gas made it cost-effective to produce our own (again, a way to consume excess natural gas). Ammonia is feedstock for a ton of cost-sensitive industrial chemistry, not just fertilizer, so costs will show up in places people might not expect.

kragen 5y ago
Interesting, why would you want to use baseload power for hydrogen electrolysis rather than solar peaks? That's the opposite of the conclusion I had reached, but maybe my crude models of hydrogen electrolysis are wrong.
- philipkglass 5y ago
  The reason nuclear-electric hydrogen appeared in past decarbonization plans was that electrolyzers were too expensive to only run at a 25% duty cycle and renewable electricity was more expensive even when the sun was shining. It currently appears that electrolyzer production is going to scale up and drop costs to meet renewables faster than nuclear projects can fix their cost/schedule problems. Here's an industry-focused article that talks about growing manufacturing electrolyzer capacity and lists some recent projects for generating hydrogen with renewables: https://www.pv-magazine-australia.com/2021/12/12/sunday-read-making-cheaper-h2/ https://www.pv-magazine-australia.com/2021/12/12/sunday-read...
  - kragen 5y ago
    Thank you very much! I feel like inherently hydrogen production via electrolysis is just not that complicated a process: it's a bottle of lyewater with some sheet metal or graphite in it connected to a DC power supply, the sort of thing you could plausibly rig up if stranded on a desert island if you happened across some metal. So I'd think that, although you can surely improve efficiency in lots of ways that increase the cost of the electrolyzer, there's some kind of electrolyzer you can make that has an optimal cost/efficiency tradeoff when you know you're going to run it at a 25% duty cycle. Maybe it isn't cost-competitive with more highly optimized always-on nuclear-powered electrolyzers, but (as the article points out) they aren't cost-competitive with steam methane reforming, either. It's wonderful to see RMI cited as "major industry analysts" next to BloombergNEF. Nobody deserves that title more.
- jandrewrogers 5y ago
  As a general rule, continuous chemistry processes are significantly more efficient than batch-y processes (just like data infrastructure). In practice, batch-y chemical processes also have higher capital costs. Operational efficiency of a given physical plant can vary widely based on operational parameters, and it is this that strongly recommends against variable duty cycles. Chemistry is an exercise in biasing a stochastic process to produce high yields of a desired chemical. This is very sensitive to small changes in the environment e.g. temperature, pressure, pH, concentration, et al. At scale, it is impossible to have a uniform reaction environment as a matter of physics, so the objective is to get as much of the environment as close to the ideal point as possible with clever engineering and then keep the system in equilibrium around that point. This involves finding approximate solutions to vast and fiendishly intractable systems of partial differential equations, that can also be turned into a real physical plant. If you have variable energy inputs, the system will very likely spend most of its time outside the high-yield sweet spot of its operational parameters. It also takes a long time for these systems to reach equilibrium (often hours or days). Effectively, these processes are binary -- at equilibrium or turned off -- with significant spin up and spin down times with terrible yields. With base load power, you can have hydrogen electrolysis as part of your continuous chemistry process. A close (but not quite) drop-in for a methane reformation subsystem. So how is variability (e.g. due to demand) often handled in real systems? They run several plants in parallel and shutdown a fraction of those plants, incurring the startup/shutdown costs. Some industrial chemistry is adequately done batch-y e.g. mining related, but most things asymptotically converge on continuous steady-state processes because there are significant economic benefits in doing so. Hydrogen electrolysis is probably amenable to batch production without a significant loss of efficiency, though it would incur storage costs you would not have with a continuous plant. The bigger issue is that the downstream processes to which hydrogen is feedstock are unlikely to be amenable to efficient batch production. Because ammonia is produced at such exceptional scales, efficiency matters, and electrolysis is already more expensive than methane reformation.
  - kragen 5y ago
    Thanks, this is really helpful in understanding the issues!

kragen 5y ago

Interesting, why would you want to use baseload power for hydrogen electrolysis rather than solar peaks? That's the opposite of the conclusion I had reached, but maybe my crude models of hydrogen electrolysis are wrong.

philipkglass 5y ago
The reason nuclear-electric hydrogen appeared in past decarbonization plans was that electrolyzers were too expensive to only run at a 25% duty cycle and renewable electricity was more expensive even when the sun was shining. It currently appears that electrolyzer production is going to scale up and drop costs to meet renewables faster than nuclear projects can fix their cost/schedule problems. Here's an industry-focused article that talks about growing manufacturing electrolyzer capacity and lists some recent projects for generating hydrogen with renewables: https://www.pv-magazine-australia.com/2021/12/12/sunday-read-making-cheaper-h2/ https://www.pv-magazine-australia.com/2021/12/12/sunday-read...
- kragen 5y ago
  Thank you very much! I feel like inherently hydrogen production via electrolysis is just not that complicated a process: it's a bottle of lyewater with some sheet metal or graphite in it connected to a DC power supply, the sort of thing you could plausibly rig up if stranded on a desert island if you happened across some metal. So I'd think that, although you can surely improve efficiency in lots of ways that increase the cost of the electrolyzer, there's some kind of electrolyzer you can make that has an optimal cost/efficiency tradeoff when you know you're going to run it at a 25% duty cycle. Maybe it isn't cost-competitive with more highly optimized always-on nuclear-powered electrolyzers, but (as the article points out) they aren't cost-competitive with steam methane reforming, either. It's wonderful to see RMI cited as "major industry analysts" next to BloombergNEF. Nobody deserves that title more.
jandrewrogers 5y ago
As a general rule, continuous chemistry processes are significantly more efficient than batch-y processes (just like data infrastructure). In practice, batch-y chemical processes also have higher capital costs. Operational efficiency of a given physical plant can vary widely based on operational parameters, and it is this that strongly recommends against variable duty cycles. Chemistry is an exercise in biasing a stochastic process to produce high yields of a desired chemical. This is very sensitive to small changes in the environment e.g. temperature, pressure, pH, concentration, et al. At scale, it is impossible to have a uniform reaction environment as a matter of physics, so the objective is to get as much of the environment as close to the ideal point as possible with clever engineering and then keep the system in equilibrium around that point. This involves finding approximate solutions to vast and fiendishly intractable systems of partial differential equations, that can also be turned into a real physical plant. If you have variable energy inputs, the system will very likely spend most of its time outside the high-yield sweet spot of its operational parameters. It also takes a long time for these systems to reach equilibrium (often hours or days). Effectively, these processes are binary -- at equilibrium or turned off -- with significant spin up and spin down times with terrible yields. With base load power, you can have hydrogen electrolysis as part of your continuous chemistry process. A close (but not quite) drop-in for a methane reformation subsystem. So how is variability (e.g. due to demand) often handled in real systems? They run several plants in parallel and shutdown a fraction of those plants, incurring the startup/shutdown costs. Some industrial chemistry is adequately done batch-y e.g. mining related, but most things asymptotically converge on continuous steady-state processes because there are significant economic benefits in doing so. Hydrogen electrolysis is probably amenable to batch production without a significant loss of efficiency, though it would incur storage costs you would not have with a continuous plant. The bigger issue is that the downstream processes to which hydrogen is feedstock are unlikely to be amenable to efficient batch production. Because ammonia is produced at such exceptional scales, efficiency matters, and electrolysis is already more expensive than methane reformation.
- kragen 5y ago
  Thanks, this is really helpful in understanding the issues!