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Units

2017-12-16T07:12:43Z

Lottery248: steam engine produces up to 900kW instead of 510kW

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The following units are important in Factorio.

Not all game elements are simulated physical correctly (for example the weight of items, currently no entity has a weight, the weight is measured in how many items can fetch into one stack), but those on this pages are!

== Power ==
Power is defined as work being done per unit of time.

=== Watt (W) ===
The basic unit of power is 1 watt (W), which is defined as '''1 W = 1 J/s ''', ie. one Joule of work being done every second.

The game commonly deals with larger units, namely kilowatts (kW) and megawatts (MW).

[[Lamp|Lamps]] use 5 kW while turned on. A [[Radar]] uses 300 kW while active - equivalent to 60 lamps.
One [[Steam engine]] is capable of outputting 900 kW.

== Work ==

Work is defined as a transfer of energy, or as energy being "spent".

=== Joule (J) ===
The basic unit of work is 1 joule (J), and is equivalent to the work done (total energy transferred) by one watt applied for one second: '''1 J = 1 W s'''.

In-game, [[Fuel]] is really just potential energy, which, when applied, does work. For example, every piece of [[coal]] burned will produce 8 kJ. One [[Accumulator]] is capable of storing 5 MJ.

It doesn't make much sense to calculate work with the much more common (at least, common in the real world) unit of kilowatt hours, because although the game runs more or less in real-time and the units are meant to be relatively realistic, 1 kW h is a lot of energy, and in fact so much so that you can't reasonably represent the value of a piece of coal that way.

== Time ==

=== [[Game-tick|Tick (1/60 s)]] ===
A 1/60 second in game. This is the shortest time fraction, the game handles.

=== [[Game-second|Second (s)]] ===
One [[Game-second|second in-game]]. This is not guaranteed to correspond to one real second. For example, slow computers may not manage to calculate an entire [[Game-tick|tick]] during the corresponding real time frame of 1/60th of a second.

=== [[Game-day|Day]] ===

A [[Game-day|day]] has 25000 [[Game-tick]]s or 416.66 game-seconds (= 6.94 Game-minutes).

== Distance / Space ==

=== [[Tile]] ===
The [[Tile]] is both used as a unit of distance/length and a unit of area. For example, the size of an object may be expressed as "2x2 tiles", which means the object covers an area of 4 square tiles or tiles². The unit of square tiles is often simplified into [[Tile]]s. It can be assumed, that a tile has the length of 1 meter.

=== [[Chunk]] ===
A [[Chunk]] is a quadratic area where one side is 32 tiles long. (1024 square tiles)

== Logistics ==

=== Throughput ===

Items per time, or fluid-units per time. A unit measurement is

items / game-minute

==== ... on Belts ====

Throughput = speed * density

See [[Transport_belts#Speed.2C_Density_and_Througput:_About_finding_the_bottlenecks|Transport belts]].

For comparison: A [[Transport belt]] transports normally about 700 items per [[Game-second|game-minute]]. A [[Fast transport belt]] up to 1200 items/min and [[Express transport belt]] nearly 1800 items / min.
See [[Transport belts/Physics|physic of transport belts]] for more information.

==== ... for logistic robots ====

Throughput depends on the distance, the number of robots and their item-stacksize. Let's assume a robot can travel 1 tile per second and can transport only one item at once. It needs also to return. Then this robot can transport 1/2 item per second. If you use 2 you can transport 1 item per second. If you double the distance, we are again at 1/2 item per second.

==== ... for train ====

(Unfinished. Needs to consider also the loading and unloading time, needs to consider maximum speed...)

=== Capacity ===

Basically items per transport-unit. This depends in many cases on the item-type you use. A [[Cargo wagon]] has a capacity for 1000 items for ore, or 2000 for steel- or copper-plates.

==== ... in stacks ====
A [[Cargo wagon]] has for example 20 stacks. The capacity of the wagon is 20 stacks. But the capacity of a stack depends on, what type of item you put into, so when stacks come into play, you need to say "Capacity of 20 stack iron-ore".

=== Density ===

Is measured in items per tile.

An item, that lays on ground has the size of 0.28 tiles². On one tile we can place 12.752041 items, which means, that we can put in the best case 12 items on one tile.
See also [[Transport belts/Physics|physic of transport belts]] for more information.

==== ... for Belts ====

For belts this is the same: We have two lanes on a belt, 3.571 items per lane or 7.143 item on one belt.

On belts there comes also another thing into play: '''Compression.''' Good compression is, when you fill a belt so, that you come to the maximum density and so to the maximum '''throughput'''.

=== ... for stacks/chests ===

On the first glance, it is simple: A chest has the size of one tile. You have X number of stack in a chest, where you can put Y numbers of items into each, so the density is simply X * Y.

The thing changes, if you use mods, that add chest-like transport boxes, which enables to pack/box items.

== See also ==

* [http://www.factorioforums.com/forum/viewtopic.php?f=18&t=5316&start=20#p54495 about calculation of throughput on a belt]
(Missing here: Capacity, which is either the volume of something or Productive capacity; Load, which is a measurement about the tightest bottleneck (waiting or running items))

User:Lottery248

2017-12-09T08:38:14Z

Lottery248:

i am lottery248 in youtube channel, located in Hong Kong. just nothing to do, and i am not really good at having active enemies attack. i am here primarily to fix some wiki page mistakes or changes.

Tutorial:Applied power math

2017-12-09T08:20:57Z

Lottery248: /* Quiz */ modified second bonus question as the steam engine produces 900kW instead of 510kW as of version 0.15

{{Languages}}
In this tutorial we'll be answering the question: '''how much coal is needed to power a factory?'''

First off, we need to know: how much power does our factory use? That's easy - you can check the electricity tab by clicking on a power pole.

[[File:power-details.png|800px]]

Here we see one radar using 300kW (the 299kW is a rounding error). Factorio uses real science here. A Watt (W) is a measure of energy transfer. A kilowatt (kW) is 1000 W, a megawatt (MW) is 1000 kW, and if you're lucky enough to ever make a factory big enough, a gigawatt (GW) is 1000 MW.

So that answers the question of how much power our factory uses. To keep our factory running at full speed we need to maintain 300 kW. For ease of comparison, we'll convert that to 0.3 MW.

Next question! How much power is stored in coal? That's also easy, because it tells us when we hover over it: 8 MJ.

[[File:coal-joules.png|300px]]

A Joule is another standard measure of stored energy. As with Watts a kilojoule (kJ) is 1000 J, and so on. There is a fixed relationship between Joules and Watts. '''1 Joule can provide 1 Watt of power for 1 second.''' As a formula:

J = W × s

So to run our factory at 0.3 MW, we need to consume 0.3 MJ every second.

== Quiz ==

Assuming perfect efficiency, how long could one piece of coal (8 MJ) run
our single radar (0.3 MW)?

<div class="toccolours mw-collapsible mw-collapsed">
'''Expand to reveal answer'''
<div class="mw-collapsible-content">
8 MJ = 0.3 MW * s
s = 8 MJ / 0.3 MW
s = 26.67

Nearly 27 seconds.
</div>
</div>

Assuming perfect efficiency, what is the maximum size factory (in watts)
a single piece of coal could run for 5 seconds?

<div class="toccolours mw-collapsible mw-collapsed">
'''Expand to reveal answer'''
<div class="mw-collapsible-content">
8 MJ = MW * 5
MW = 8 MJ / 5
MW = 1.6

1.6 megawatts.
</div>
</div>

'''BONUS!''' A ton of real world coal [http://hypertextbook.com/facts/2006/LunChen.shtml contains about 21 GJ]. How much does a
piece of Factorio coal weigh?

<div class="toccolours mw-collapsible mw-collapsed">
'''Expand to reveal answer'''
<div class="mw-collapsible-content">
The energy ratios will match the weight ratios, so:

8 MJ / 21000 MJ = weight / 1000 kG
weight = (8 MJ / 21000 MJ) * 1000 kG
weight = 0.38 kG

About 400g! Still doesn't explain how our character can carry so much of it...
</div>
</div>

== Efficiency ==

Let's test it! We should be able to run a radar for 27 seconds, right? Using a setup with a single boiler, steam engine, and radar, we can drop a single piece of coal in the boiler and see how long the radar runs.

[[File:radar-example.png|800px]]

We barely got 20s! What's wrong? We are generating less power than expected.
Let's measure using an accumulator.

[[File:Accumulator-example.png|800px]]

We started with 8 MJ in the coal, but only 4 MJ ended up in the accumulator.
This is because, like in the real world, some energy is lost along the way as
waste. In this case, only 50% is making it into our accumulator. In Factorio,
this loss happens in the boiler, and it actually tells us this in the item details! You can think of the waste 50% as going into the pollution it generates...

[[File:boiler-details.png]]

Now we have everything we need to answer our initial question: '''how much coal do we need to power our factory?''' Well, the question actually needs to be a bit
more precise: how much coal do we need ''per second'' to power our factory?

<div class="toccolours mw-collapsible mw-collapsed">
'''Aside: why did the radar run for 20s and not 13.5s (50% of 27s)?'''
<div class="mw-collapsible-content">
Because it doesn't turn on and off instantly. As you can see in the graph, it ramps up then ramps down. Technically, if you measured the area under the curve it would give you the expected 4 MJ.
</div>
</div>

== Quiz ==

How much coal per second is needed to power a 20 MW factory?

<div class="toccolours mw-collapsible mw-collapsed">
'''Expand to reveal answer'''
<div class="mw-collapsible-content">
Since <code>J = W × s</code>, a 20 MW factory will consume 20 MJ/s. We'll need 40 MJ/s input due to the 50% boiler efficiency loss. Since coal contains 8 MJ, we'll need '''5 coal per second''' (<code>5 × 8 MJ = 40 MJ</code>).
</div>
</div>

'''BONUS!''' How many [[Mining|mining drills]] are needed to produce that much coal?

<div class="toccolours mw-collapsible mw-collapsed">
'''Expand to reveal answer'''
<div class="mw-collapsible-content">
Per the linked page, an electric mining drill produces ~0.5/s, so we'll need '''10 electric mining drills''' (<code>10 × 0.5 = 5</code>).
</div>
</div>

'''SECOND BONUS!''' The average American household uses [https://www.eia.gov/tools/faqs/faq.php?id=97&t=3 3.2 GJ in a month] (typically expressed as ''888 kilowatt hours''). How much Factorio coal would be needed to power one of these homes for that period, and how many homes could a steam engine support ([[Steam_engine|900 kW]]), assuming the power is used at a constant rate? (Assume 30 days in a month.)

<div class="toccolours mw-collapsible mw-collapsed">
'''Expand to reveal answer'''
<div class="mw-collapsible-content">

3.2 GJ = 3,200 MJ
3200 MJ / (8 MJ * 50%) = 800

3200 MJ / 30 days / 24 hours / 60 minutes / 60 seconds = 1,235 W
900,000 / 1235 = 728

800 pieces of coal per household, and a single steam engine could power 728 households by approximate.
</div>
</div>