Inserter power usage (aka don't use fast inserters)

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5th Earth
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Inserter power usage (aka don't use fast inserters)

Post by 5th Earth »

So, a reply to a comment I made on a youtube video prompted me to break out the spreadsheets...

The question is, what's the most energy efficient way to use inserters? In other words, how do we maximize items per second per kW? Well, I crunched numbers and found some interesting things.

First, my base assumptions: all my calculations were based on the 0.18 chest-to-chest IPS listed on the wiki. I don't think anything changed for 1.0, and I didn't want to get bogged down in the minutia of how inserters and belts interact.

Now, some conclusions:

1: Idle power usage is basically irrelevant for performance calculations. Every inserter's active power usage is so much bigger than its idle power that the differences between different types of inserters are obliterated the moment you start moving any reasonable quantity of items.
2: Burner inserters suck. But that's not really a surprise. By far the highest energy usage per IPS. BUT, they are the only ones with zero idle power usage. So for extremely low IPS, (less than .027, or about 1.6 items per minute) they are actually the best option. There may be scenarios where this is relevant, I guess?
3: Long arm inserters use almost exactly as much power per IPS as regular inserters. They have a higher maximum throughput due to their higher speed, but this is exactly cancelled by their increased energy usage. I assume this is by design.
4: Fast inserters suck. I was surprised by this, but unless you actually need the high IPS in limited space, you are always better off using multiple regular inserters instead. 3 regular inserters will move more IPS, for less energy, than one fast inserter. You should only ever use fast inserters when space constrained.
5: Filter inserters are like fast inserters that use more power. This should be obvious from their stats, but you really shouldn't ever use them unless you have to.
6: Stack inserters suck in the early game. Like fast inserters only more so, any combination of regular or fast inserters that produces the same IPS will use less power.
7: Stack inserters are much better by the time you research stack bonus 7. They actually beat fast inserters on IPS/kW, by a significant margin. You should always use them instead of fast inserters for high IPS applications. (another reason fast inserters suck). In fact, the IPS/kW gets so good that they almost beat even regular inserters for efficiency, assuming the regular inserter is at max capacity.

I want to repeat the biggest conclusion here, because I think it will actually impact my designs: Fast inserters are really inefficient. Unless you are space constrained, you are always better off using multiple regular inserters. And, in the late game, stack inserters are always better for high IPS in limited space and you pretty much should never use fast inserters.

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Re: Inserter power usage (aka don't use fast inserters)

Post by 5thHorseman »

Huh. I never did the math but always just assumed the opposite of your conclusion, that a single fast inserter was in all ways better than 2 regular inserters.

I guess it's the price you pay for compactness.
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Re: Inserter power usage (aka don't use fast inserters)

Post by Yoyobuae »

Don't think many care all that much about power efficiency. And if you did you'd be worrying 100x more about drills/furnaces/assemblers.

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Re: Inserter power usage (aka don't use fast inserters)

Post by sparr »

5th Earth wrote:
Sun Aug 23, 2020 4:47 am
2: Burner inserters suck. But that's not really a surprise. By far the highest energy usage per IPS. BUT, they are the only ones with zero idle power usage. So for extremely low IPS, (less than .027, or about 1.6 items per minute) they are actually the best option. There may be scenarios where this is relevant, I guess?
I wonder if there's a situation where I have an inserter handling fuel and inserting fewer than 1.6 items per minute...
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Re: Inserter power usage (aka don't use fast inserters)

Post by Koub »

@OP : I'm not surprised in the slightest manner with your conclusions. Eyeballing consumption and speed, it seemed to me obvious. The only things eyeballing said nothing is the item per minute threashold a burner inserter gets more efficient than a regular inserter, and the stack bonus research at which stack inserters get better than fast inserters.

However you didn't tell us what fuel you used for the burner inserter : burner inserters have to refuel themselves more often with coal than with nuclear fuel. That should have an impact on the overall consumption. Or maybe you didn't account for that extra swing to fuel themselves ?

Overall, the fast inserters being less efficient than normal inserters ips wise is kind of expected. It's how tiered entities usually work.
AM1 : 77.5 kW, speed 0.5
AM2 : 155 kW, speed 0.75
AM3 : 388 kW, speed 1.25
if you normalize that to powerconsumption for equivalent speed 1, you get :
AM1 : 155 kW per speed 1 craft
AM2 : 207 kW per speed 1 craft (rounded to the closest kW)
AM3 : 310 kW per speed 1 craft (rounded to the closest kW)

Or said otherwise, 6 AM3 produce as fast as 10 AM2 and 15 AM1.
6 AM3 : 2328 kW
10 AM2 : 1550 kW
15 AM1 : 1162.5 kW

As you get up tiers, you get more features (fluid input, more module slots, smaller footprint) as you give up efficiency.

As an additional note, you're restricting yourself to inventory to inventory transfer. You did well, because it's the only way to get predictable and repeatable results. However if you were to test belt to inventory or inventory to belt transfers, I suspect your results would significantly vary (but you'd have to make them for all 4 orientations).
Koub - Please consider English is not my native language.

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Re: Inserter power usage (aka don't use fast inserters)

Post by Khagan »

5th Earth wrote:
Sun Aug 23, 2020 4:47 am
regular inserters will move more IPS, for less energy, than one fast inserter. You should only ever use fast inserters when space constrained.
As Koub has pointed out, this is not surprising. The simplest tool that does the job is usually also the cheapest.
5th Earth wrote:
Sun Aug 23, 2020 4:47 am
Stack inserters are much better by the time you research stack bonus 7. They actually beat fast inserters on IPS/kW, by a significant margin. You should always use them instead of fast inserters for high IPS applications.
Your statement about IPS/kW is true (for chest-to-chest), but your conclusion is not, because you are overlooking the hugely higher capital cost of the stack inserter.

If we have a fast inserter running flat out chest-to-chest, and replace it by a stack inserter moving items at the same rate, the energy consumption (ignoring drain) drops from 46kW to 33kW. But the stack inserter costs 90 resources to make, and the fast inserter only 12.5. Even using solar, 13kW of power only costs about 29 resources to produce (and nuclear power about a twentieth of that). So it's much cheaper to use the fast inserter, and increase power production to compensate. The stack inserter wins only if it is replacing three or four fast inserters (and you are using solar power).

And of course, belt-to-chest or chest-to-belt, the fast inserter is more power efficient to start with, since the stack inserter is only about twice as fast instead of four times. Once again, the simpler tool is cheaper.

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Re: Inserter power usage (aka don't use fast inserters)

Post by 5th Earth »

Koub wrote:
Sun Aug 23, 2020 8:33 am
@OP : I'm not surprised in the slightest manner with your conclusions. Eyeballing consumption and speed, it seemed to me obvious. The only things eyeballing said nothing is the item per minute threashold a burner inserter gets more efficient than a regular inserter, and the stack bonus research at which stack inserters get better than fast inserters.

However you didn't tell us what fuel you used for the burner inserter : burner inserters have to refuel themselves more often with coal than with nuclear fuel. That should have an impact on the overall consumption. Or maybe you didn't account for that extra swing to fuel themselves ?

(...)

As an additional note, you're restricting yourself to inventory to inventory transfer. You did well, because it's the only way to get predictable and repeatable results. However if you were to test belt to inventory or inventory to belt transfers, I suspect your results would significantly vary (but you'd have to make them for all 4 orientations).
Yeah, I haven't figured out the break-even for stack research that makes stack inserters better than fast inserters because a full table of stack inserter IPS per research level wasn't on the wiki. At some point I'll have to do my own measurements and figure it out.

Re: the type of fuel for burner inserters, you're right, I hadn't taken that into account. The wiki says one coal will last for 57 swings, so that means the inserter will use 1/57 of its fuel to power itself. That's 1.8% lost. Solid fuel lasts 178 swings, or 0.6%. So worst case scenario, we'll actually need to transfer no more than one item every 1.6*1.018 minutes, which is only a few seconds longer. It has an effect but it's pretty small. And if you are using it for a nuclear centrifuge because you are a genius madman like sparr, then the energy lost will be trivial.

I'm aware that inventory-to-inventory leaves out most of the real-use applications we'll see. And of course, I know you often can't reliably use regular inserters on the faster belt types, so that's also a limitation to the applicability. My assumption is that even though the specific kW/IPS used changes in different configurations, the trends between types of inserters will stay the same except in odd edge cases. Though I know that's an assumption that may be wrong, especially for stack inserters that act really weird in some arrangements. YMMV.
Last edited by 5th Earth on Sun Aug 23, 2020 11:34 pm, edited 2 times in total.

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Re: Inserter power usage (aka don't use fast inserters)

Post by 5th Earth »

Khagan wrote:
Sun Aug 23, 2020 9:34 pm
If we have a fast inserter running flat out chest-to-chest, and replace it by a stack inserter moving items at the same rate, the energy consumption (ignoring drain) drops from 46kW to 33kW. But the stack inserter costs 90 resources to make, and the fast inserter only 12.5. Even using solar, 13kW of power only costs about 29 resources to produce (and nuclear power about a twentieth of that). So it's much cheaper to use the fast inserter, and increase power production to compensate. The stack inserter wins only if it is replacing three or four fast inserters (and you are using solar power).

And of course, belt-to-chest or chest-to-belt, the fast inserter is more power efficient to start with, since the stack inserter is only about twice as fast instead of four times. Once again, the simpler tool is cheaper.
In the long run, the initial capital cost will be overshadowed by the continuous and ongoing fuel costs. I don't know what the break even point is, but it's like buying a more expensive car that has better fuel economy. Eventually the money you save on fuel will be more than the initial price difference. And since the lifespan of an inserter is infinite (barring biter attacks) we have as much time as necessary to recoup the initial investment.

You're right that restricting myself to chest-to-chest transfers excludes the differences involved in belt-involved transfers. It was a simplification to find out the initial trends, since there are so many variables otherwise. That'll be for future research I suppose.

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Re: Inserter power usage (aka don't use fast inserters)

Post by Khagan »

5th Earth wrote:
Sun Aug 23, 2020 11:17 pm
In the long run, the initial capital cost will be overshadowed by the continuous and ongoing fuel costs. I don't know what the break even point is
For solar power there are no fuel costs, and no break-even point, ever.

For mature nuclear power, it takes something like 1600 hours at capacity for the fuel costs to add up to the same as the capital cost of solar. The break-even point for replacing a fast inserter by a stack inserter would be over 4000 hours of continuous operation, and that is assuming both
  1. that uranium ore is as valuable as iron and copper (it isn't, not really) and
  2. that a unit of resources in thousands of hours time is as valuable as the same unit now (it isn't, not remotely).
Any vaguely sane discount rate for future resources will result in the same conclusion as for solar: no break-even point.

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