While at a technology conference last week, someone explained flow batteries to me. My mind immediately went off to think of ways to use them in Factorio, if only they existed. So why not make them exist?
I wrote them up in a Gist at https://gist.github.com/ojacobson/bbaaf ... 807e9529df and now I'm looking to figure out if they can actually be realized with the modding tools in Factorio. I had a quick read through the base mod files, and it's not clear whether what I have in mind is possible, unfortunately. Can a building produce power sometimes, consume power at other times, and only do so when it's possible for a specific production process to progress using the ingredients present at the building?
[Idea] Flow Cells
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Moffmaster
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Re: [Idea] Flow Cells
That's a very nice idea!
I imagine flow cells will be better at storing large amounts of power in tanks, though their peak-power throughput is limited by the number of actual cells. So they would be a good nighttime storage solution for a solar-based energy system.
I imagine flow cells will be better at storing large amounts of power in tanks, though their peak-power throughput is limited by the number of actual cells. So they would be a good nighttime storage solution for a solar-based energy system.
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zebediah49
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Re: [Idea] Flow Cells
They absolutely can be done. Reactors has pretty nicely demonstrated how you can couple machine entities. I'm distinctly tempted to try my hand at implementing it (at least a relatively simple version of it) myself.
As I see it, there are two variant options:
1. A single entity that acts as an accumulator, and converts between fluids. Charges and discharges as appropriate. Custom fluid box handling.
2. A modified version of the chemical plant, which either charges or discharges depending on setting.
I think I lean towards the first, although it would be harder to do.
As for actual content, I would probably want to try to match (or at least be vaguely reasonable with) Factorio's basic battery chemistry and statistics. Also, I like the idea of a two-component system better than a one-component system. One-component just seems weird from a chemistry point of view; two- allows it to be a better payoff in exchange for the complexity increase. I'm not sure what a minimal-modification choice in the Factorio universe would look like though.
Energy density: From accumulators, we have that 1 Iron + 1 Copper + 2 Sulfuric Acid == 1MJ worth of energy storage. Also, 60kW of transfer, though that's a little weird on scale. If this works out to a total of 4 fluid units per MJ, that's 625MJ/tank, which is around 70 MJ/square. For comparison, accumulators are 1.25MJ/square. This (pretty high) number will, of course, go down if one considers adds the space used by the extra infrastructure, so I'll assume it's okay for the moment. Another comparison is hot water, which is 212.5 MJ/tank. That makes this more space-efficient.. if you don't include needing empty tank space. I suppose a clever solution could re-use tank space. A solution using barrels (480*25=3GJ/square) would be very very dense, but I wouldn't want to primarily balance around that problem (IIRC it's supposed to get fixed in 0.15?).
Power density: Accumulators are 75kW/square. Steam engines are 34kW/square. I would probably make the flow battery station somewhere around the higher end of that; maybe 500kW for the 3x3 (~55kW/square).
This would mean that a basic system that could satisfy 1 GW throughout a 125s night, would have two parts. One part consisting of a row of 2k undergound-pipe-connected cells would be take roughly 11 squares tall, for a net power density of 15 kW/square. That's 66k squares for the power. Storage would be another 400 tanks, for a total of 3600 squares. Net total is approximately 70k squares. To do this with accumulators, you'd need 25k accumulators, for 100k squares. So, it's a *little* more space efficient -- mostly because of the huge pipe inefficiency in my build. Without that problem, it'd only be 2k cells, for 18k squares. Total of 21.6k squares. Four lines of cells with pipe lines between them would get you 20kW/square, and "only" take 52.5k squares (55k total).
So, with some annoying infrastructure investment, you're looking at nearly twice the energy density for an "overnight" system.
One additional concern: If directly based on accumulators, the flow battery cell would be drained along with regular accumulators. I believe that the drain rate is proportional to power offered, so at full drain, the accumulator goes flat in 17 seconds, while the flow system survives however long it can. This could be avoided by having separate secondary-producer and secondary-consumer entities, but there are a few ways of doing this -- ranging from separate charge and discharge stations, to a circuit-controlled combined station (I think I like this option), to an automatically controlled combined station. To make something like this work decently I think a baseline circuit network control system does make sense.
As I see it, there are two variant options:
1. A single entity that acts as an accumulator, and converts between fluids. Charges and discharges as appropriate. Custom fluid box handling.
2. A modified version of the chemical plant, which either charges or discharges depending on setting.
I think I lean towards the first, although it would be harder to do.
As for actual content, I would probably want to try to match (or at least be vaguely reasonable with) Factorio's basic battery chemistry and statistics. Also, I like the idea of a two-component system better than a one-component system. One-component just seems weird from a chemistry point of view; two- allows it to be a better payoff in exchange for the complexity increase. I'm not sure what a minimal-modification choice in the Factorio universe would look like though.
Energy density: From accumulators, we have that 1 Iron + 1 Copper + 2 Sulfuric Acid == 1MJ worth of energy storage. Also, 60kW of transfer, though that's a little weird on scale. If this works out to a total of 4 fluid units per MJ, that's 625MJ/tank, which is around 70 MJ/square. For comparison, accumulators are 1.25MJ/square. This (pretty high) number will, of course, go down if one considers adds the space used by the extra infrastructure, so I'll assume it's okay for the moment. Another comparison is hot water, which is 212.5 MJ/tank. That makes this more space-efficient.. if you don't include needing empty tank space. I suppose a clever solution could re-use tank space. A solution using barrels (480*25=3GJ/square) would be very very dense, but I wouldn't want to primarily balance around that problem (IIRC it's supposed to get fixed in 0.15?).
Power density: Accumulators are 75kW/square. Steam engines are 34kW/square. I would probably make the flow battery station somewhere around the higher end of that; maybe 500kW for the 3x3 (~55kW/square).
This would mean that a basic system that could satisfy 1 GW throughout a 125s night, would have two parts. One part consisting of a row of 2k undergound-pipe-connected cells would be take roughly 11 squares tall, for a net power density of 15 kW/square. That's 66k squares for the power. Storage would be another 400 tanks, for a total of 3600 squares. Net total is approximately 70k squares. To do this with accumulators, you'd need 25k accumulators, for 100k squares. So, it's a *little* more space efficient -- mostly because of the huge pipe inefficiency in my build. Without that problem, it'd only be 2k cells, for 18k squares. Total of 21.6k squares. Four lines of cells with pipe lines between them would get you 20kW/square, and "only" take 52.5k squares (55k total).
So, with some annoying infrastructure investment, you're looking at nearly twice the energy density for an "overnight" system.
One additional concern: If directly based on accumulators, the flow battery cell would be drained along with regular accumulators. I believe that the drain rate is proportional to power offered, so at full drain, the accumulator goes flat in 17 seconds, while the flow system survives however long it can. This could be avoided by having separate secondary-producer and secondary-consumer entities, but there are a few ways of doing this -- ranging from separate charge and discharge stations, to a circuit-controlled combined station (I think I like this option), to an automatically controlled combined station. To make something like this work decently I think a baseline circuit network control system does make sense.