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> Let me run these ammonia producing machines at full power for a bit.

The problem with this is the capex and running costs of that kind of machinery make it expensive to keep idle. It can be uneconomic even with free electricity.

Where are the costs. Many factories are only used 8 hours a day despite the high costs - it isn't worth the additional cost to have employees work overnight. Some really energy hungry factories traditionally run only overnight when energy is cheap, and they shutdown for yearly maintenance in December (thus freeing up their normal energy use when everyone is running Christmas lights) Now that wind and solar are coming online those are changing how they work.

Different factories have difference costs. When energy is significant they consider that. When energy is not significant they just run when it works out.

> Many factories are only used 8 hours a day despite the high costs

I don't have a lot of direct experience but my dad worked in factories most of my childhood. Every single one ran nearly 24/7. Was that a chance occurrence of the types of factories we had near where I grew up?

The only confirmed example I know of is Harley-Davidson, roughly during the boom of cruiser motorcycles (1995-2010?): They only ran one shift, but the PR of waiting lists and extremely high instant resale prices made the choice appealing in the face of the capital costs.

Are you asking if all factories are like the ones that you grew up near?

My understanding is that manufacturing tends to be the way you describe. I'd be surprised if that held true for all sorts of factories, especially in chemical production. Just a guess but I think paying chemical engineers for overnight shifts might cut into profits somewhat

EDIT: another comment sparked a memory, I'm thinking specifically of batch operators.

Stopping and restarting chemical plants is usually horribly expensive. Most of them run 24/7, non-stop, even if the companies have negative profit on some of the products.

Usually there will be only a single engineer or maybe two on staff for the night shift. But paying regular operating staff an additional 50% night shift bonus to keep the factory running is very often worth the price.

The night shift extra is usually much closer to 50 cents than 50 percent. A lot of places even give the night shift the same pay, especially when the labor market is favorable to employers.

That's crazy. In many countries (e.g. mine) night shift is an unwanted pay increase, and often on a week-on, week-off basis.

> Many factories are only used 8 hours a day despite the high cost

Is this true in chemicals?

Which chemical? Some yes, some no. Some processes work better in continue runs, some you are doing batches. Some batches take a few weeks, some are hours...

> Which chemical?

Any industrially-produced chemical where continuous production is possible. I haven’t heard of such systems being competitive if left idle so someone can sleep.

Continuous production implies at least a few people 24x7. Not all chemicals are continuous production. Often there is a choice of processes when you build a factory.

> Continuous production implies at least a few people 24x7. Not all chemicals are continuous production

Yes. I'm asking if there is a chemical-production process that can be run 24/7 but which isn't due to labour shortages somewhere that doesn't result in such production being shut down (or protected)?

Chemicals are globally-traded commodities. Some are perishable and/or difficult or even illegal to ship. So there is regional price variance. But ceteris paribus, if it can be run continuously, production will shift to where it is.

Normal operation of ammonia plants and methanol plants has been 24/7 for decades. Most other commodity chemicals too.

Loading & unloading ships & barges as well.

Some places only load railcars & trailers during days.

Also it's common for engineers to only work straight days and often their office is not on site, they actually only make visits. They do it as needed and can be very dedicated and effective, but of course they can't touch anything because that requires a unionized operator.

I've worked in two factories in my life. Dairy, and Printing. Dairy was 24/7/365. Printing was (averaging) 20/7/365 (product/layout change, maintenance, cleaning, etc.)

My father was a fireman. Knowing what I know from him, I would never go to work for a factory that they got THOSE massive energy demanding machines that run non-stop and the fuel is ammonia. It is a near-certain death sentence, especially in 'some countries' where safety is 'a bit more relaxed'.

> Ammonia is a great not-on-demand consumer of electricty.

This does not follow. The cost efficiency of ammonia production is highly dependent on the process being continuous and steady state. Every analysis that says ammonia is cost effective as a fuel is based on an efficient continuous process as a cost assumption.

If you are constantly starting and stopping based on electricity availability then your ammonia just became much more expensive. In which case, it is probably no longer cost effective as a fuel. Mixing "best possible price" and "worst possible process" and pretending these represent the same instance of reality is misleading to say the least.

> The cost efficiency of ammonia production is highly dependent on the process being continuous and steady state.

Hydrogen is the overwhelming energy input to ammonia production. Hydrogen is readily storable -- this is done even today, when the hydrogen comes from natural gas, to smooth things out to keep the ammonia plant running -- so intermittency of renewables will be almost entirely countered by doing the same thing and storing the green hydrogen.

What matters is cost of electrolysers, but they have been getting very cheap in China.

It is not just the cost of inputs.

Ammonia synthesis is a high-pressure high-temperature process. One of the reasons to use a continuous steady-state process is that cycling it up and down causes thermal and pressure fatigue in the reactor. The safe operating life of a reactor can be surprisingly short if it is not operated at a steady state. If you want this to scale, it needs to be low maintenance and have a long operating life.

You could in principle centralize ammonia production with sufficient reactant reserves to ensure continuous production from variable low-density energy sources like solar or wind. However, this would require hydrogen pipelines that largely don't exist and would take a long time to build. We can't repurpose existing natural gas infrastructure and similar because they weren't built with alloys resistant to hydrogen embrittlement. One of the big economic advantages of using methane for ammonia is that it takes advantage of the millions of kilometers of natural gas distribution pipeline that already exists.

I'm not averse to the idea but the enthusiastic proponents are pretending like the practical realities of industrial chemistry don't apply to them. We aren't going to get to a green future with rainbows and unicorns, we need to brutally realistic about the true requirements.

I wasn't talking about the cost of inputs, I was talking about their putative intermittency.

The argument that was being made seemed to be "renewables are intermittent, therefore ammonia synthesis based on renewable energy must be intermittent, or else use expensive storage". The counterargument is that hydrogen is the overwhelmingly most important input, and it is highly storable, so the intermittency of the inputs can be largely avoided at modest cost, allowing the ammonia plant to run 24/7.

You may not be aware, but we already have hydrogen pipelines coupled to ammonia plants. The US has ~1000 miles of hydrogen pipelines for this purpose. It's also not obvious to me why pipelines would necessarily be needed. After all, the ammonia plant could be built where the hydrogen is stored.

Can factories install local battery banks to cover a day’s utilization? Charge up the batteries on the cheap electricity during noon and run the plant off of those reserves. I assume other industries are already running these cost optimization analyses as the renewable electricity market continues to develop. There is a balancing point between the capex and opex, but unless it is insanely energy hungry (like aluminum), that seems possible.

> but unless it is insanely energy hungry (like aluminum)

Producing a ton of hydrogen by electrolysis requires ~3x the energy to produce a ton of aluminum. It is, in fact, "insanely energy hungry". This isn't necessarily a problem but it does create logistical challenges.

What comes back to the fact that you only need batteries for the ammonia production. Hydrogen production is a low-pressure process, and optionally even low-temperature.

It takes 11 MW of electricity to make 1 ton of ammonia, ammonia plants can make 1000 to 3000 tons a day. Providing battery storage for that production rate for 24 hours would probably cost more than the plant itself.

> It takes 11 MW of electricity to make 1 ton of ammonia

Do you mean MWh? Because the units given don't make sense.

But 11 MWh would be too low.

> You could in principle centralize ammonia production with sufficient reactant reserves to ensure continuous production from variable low-density energy sources like solar or wind.

I'm probably missing something here but why would you need to pipe hydrogen to the plant, rather than just generating it on site from power drawn from the grid?

Energy density mostly and being able to deliver that power where you need it. Aluminum plants are co-located with large-scale power plants, famously hydroelectric, for the same reason. Above certain power requirements, you essentially need the power generation to be onsite.

Hydrogen requires 3x the energy of aluminum per ton, so it is an even bigger problem for hydrogen. Unlike aluminum, it is feasible to have large numbers of small hydrogen production plants but then you need to transport all that hydrogen at an acceptable scale.

> Above certain power requirements, you essentially need the power generation to be onsite.

Is this due to transmission losses or just because you couldn't feasibly build enough capacity cables to transmit large amounts of power over long distances?

A single ton of hydrogen requires ~50 MWh of electricity. Small special-purpose ammonia plants, which are common for some industrial applications, typically require on the order of 50 tons of hydrogen per day. This would require ~2.5 GWh of electricity per day via electrolysis. To put that in context, that is in the same ballpark as the average output of the largest solar farms ever built in the US.

The largest ammonia plant in the US requires around 2,000 tons of hydrogen per day. That would require 100 GWh per day to produce by electrolysis, which would require the entire output of a large hydroelectric or nuclear power plant, much like large aluminum refineries. Otherwise, you need to move a lot of electricity or a lot of hydrogen to have good efficiency, and there is infrastructure for neither.

Converting natural gas into hydrogen is also energy intensive. One of the big advantages of natural gas is that your hydrogen source is also your energy source and there is vast infrastructure for moving natural gas around.

Building green hydrogen pipelines likely makes more sense than trying to backhaul electricity from diffuse sources. A single hydrogen pipeline can reify a lot of electricity production without the concomitant transmission and management infrastructure.

A ton of hydrogen seems to occupy a cube with a 23 meter side. Wonder if a bunch of those could be built to hold the excess gas for night time operation.

100GWh is not small, but it's not impossible. The largest solar farm in operation is 5GW, and that could get you theoretically halfway there operating 10 hours a day.

It feels like the challenges are a lot easier to solve than with fusion or nuclear.

It is doable in theory but would require the construction of large-scale supporting infrastructure that currently doesn't exist. I am not optimistic about our ability to undertake infrastructure projects of this magnitude without it taking several decades and incurring obscene cost overruns that make even the most pessimistic economic models look optimistic.

This will definitely be harder than nuclear. The expansive land use requirements means the legal battles pertaining to that would almost certainly span many decades. At least with nuclear there is a limited number of people that need to sign-off to have a viable project -- reforming that process probably would be simpler.

The issue doesn't appear to be storage, but transmission. Hydrogen can leak through metal and lead to it becoming brittle, so you can't use conventional natural gas pipelines to transport it.

Exactly, these tanks can be giant balloons right next to the solar panels all feeding the in-situ ammonia plant.

That was my thinking, but I think what he is saying is that power plants won't generate enough electricity to make building an in-situ ammonia plant economical. You need to network power plants together to operate a centralized ammonia plant 24/7, and the network to move this energy (whether in the form of hydrogen or electricity) doesn't currently exist.

The land area of an all-in-one plant is maybe the biggest unknown for me with respect to just getting ownership and permits and such. But it's fun to imagine just picking a giant plot somewhere in the desert and plopping down 20 GW of solar panels, enough hydrogen storage to keep the less energy intensive steps operating throughout the night, and presumably batteries for whatever still requires electric power while panels are offline. Water and air in, sweet sweet ammonia out. :-)

Cloudy weather would be an interesting problem I guess.

I can’t imagine it wouldn’t be stored either as liquid or at least pressurized.

Steam has something like 200x the volume of the water it’s boiled from.

One thing you can do there is have an onsite energy storage mechanism (battery, gravity, etc) and run the process 24/7, keeping the energy storage topped up whenever the cost of electricity falls below whatever threshold.

Worst comes to worse you run on grid for a few hours.

Liquid ammonia takes less energy and volume than liquifying hydrogen.

This has nothing to do with hydrogen as an input to the ammonia production process. This hydrogen is not liquefied, even if it is temporarily stored (as a compressed gas, for example underground in solution mined salt caverns.)

Do you have concrete capex and opex numbers for ammonia-from-electricity plants? I understand we should expect those to go down over time because of the learning curve, but I don't even know their order of magnitude right now. It would also be nice to have an idea of how much efficiency the electrolyzers lose when operated intermittently instead of continuously (so, for example, you can't keep them at their optimal temperature). But, since we're presupposing that intermittent electrical energy will be very cheap, efficiency is less important than capex per output and non-energy opex.

Supporting your point about solar panels continuing to be cheap, "mainstream" panels went up to 0.11€ per peak watt last month: https://www.solarserver.de/photovoltaik-preis-pv-modul-preis... which was a new historic low price in September and down 21% from 0.14€/Wp in February of last year, itself a historic record low price at the beginning of last year.

The last time something like this happened to the energy supply, it was James Watt's steam-engine.

What are the relative costs of producing methanol or ammonia from a kilowatt hour of electricity? I've always assumed methanol would be cheaper over all because it's less deadly.

Wouldn't this imply that the ammonia consumption would have to be near the solar plant?

No? For similar reasons that fossil fuel consumers don't need to be near an oil well.

You'd have to ship the ammonia to the point of use, which is going to be significantly more hazardous

If ammonia cannot be shipped safely than the whole thing is moot. We're talking about "shipping" ammonia halfway around the world in the fuel tanks of these ammonia fueled ships. If storing it long term in fuel tanks can be done safely, than so can shipping it to port.

This also means ammonia may end up getting produced at the globally best places, the places where the solar resource is extremely good, like Chile, Namibia, parts of the middle East, then shipping elsewhere.

Sunny places with good ports and cheap land.

Shipping ammonia is commonly done already. For example, the first few search results for "ammonia tanker" has a story of Maersk ordering up to ten new tankers with 93000 cubic metre capacity each.

This is illogical - we ship a live nuclear reactor around the world in a nuclear carrier or icebreaker. But you cannot take it out and put it on a truck

That has more to do with the design of the vessel than anything.

You “ship” electricity near a port via the electric grid, and then make ammonia near or in the port. Economies of scale might favor having a few ammonia factories and then shipping it around by boat.

Ammonia makes zero sense as a general use fuel, but ships need MW of power over several days and aren’t in populated areas.

Assuming, it’s actually viable which isn’t guaranteed.

OK, that sounds like a good plan. But that's the opposite of what was proposed further up this thread.

It depends on whether you prefer to transfer electricity or ammonia. You get to pick whatever is easier, which caps the difficulty at not high. The suggestion of shipping ammonia was for the sake of convenience, not a burden. It's optional.

the actual post I replied to originally said

"build the ammonia producing plant close to your solar/wind parks"

You can't pick that and then decide not to transfer the ammonia and decide not to transfer the electricity. Unless your solar plan is at the loading dock or something.

The suggestion of shipping ammonia was for the sake of convenience, not a burden. It's optional.

Yes you have to transfer electricity in that case. We already know transferring electricity is easy.

Don't get hung up on "picking" one as if the downsides get locked in at the pre-design phase. If it's difficult to transfer ammonia then nevermind go back to the existing easy option of wires.

In other words, if that specific detail doesn't work out, it is not an argument against ammonia. It was just a potential bonus, not core to the idea. And it doesn't fundamentally change things. It's not the "opposite" plan.

Someone makes a statement. I point out that statement has implications. Someone then suggests an idea that is counter to the original statement. I point out that is inconsistent. Your response is "Don't get hung up on".

Your argument at this point has just devolved into some variant of "don't confuse me with the facts"

You said the plan was the opposite, but it was only a tiny optional detail that's opposite.

The phrasing in that comment rejected the original plan as a whole, and that's not right.

Also the comment you called a "good plan" was still talking about shipping ammonia as a maybe! So even in that detail it's not the opposite of the original comment.

I think your first comment was fine, but it's not your first comment that I replied to.

I wouldn’t get that hung up on the specifics when we are using terms like ‘near’ which is why I said boats for economies of scale.

I was thinking of navigable waterways which are common near major wind farms and some solar, not just major ports which rarely have a lot of space available. The UK is already facing issues with moving offshore wind around the country, an Ammonia plant could theoretically make a lot of sense.

It only needs to be easier to ship than hydrogen.

We're already doing this with methanol in Sweeen though. So what's the point?