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Looking at the forums and reddit, it seems like a lot of people believe Efficiency Modules reduce pollution, but I can't actually find anything within the wiki or the game itself about it. I know they can reduce pollution indirectly (less power = less pollution from steam engines) but does putting them into a machine reduce the pollution caused by that machine?

Almost all machines have 2 sources of pollution (assuming not full solar), the steam engines are one, the machine itself is the other.
Eff. modules reduce both of these, meaning even a full solar player can see some use to eff. modules.

They do, look at the machines tooltip without a module in it, put one in and look again. Pollution is reduced by the % of the module (i think, not tested). It's because the pollution depends on the power-consumption.
So efficiency modules give you double the benefit when using steam as your powersource

Correct : pollution comes from two sources :
- The facility producing energy, if it's steam based
- The consumption of the energy. Any facility consuming less will pollute accordingly less.

Okay, so they do!

Other modules explicitly say they increase pollution, and no where in the wiki, the research description, or the efficiency module tooltip does it ever say that it reduces pollution.

Based on Choumiko's suggestion I tried putting two assembly machines side by side and comparing, and the one with efficiency modules in it generates less pollution.

In case anyone else is looking at this, the modules reduce pollution by the same percentage they reduce electric usage, and are capped at 80%.

Koub, your explanation of how pollution is generated makes sense, but I wonder if that isn't more of a "developer" answer. From my (a player's) perspective, it seems strange that other modules have specific notes on how they affect pollution, where it's expected that you know electricity generates pollution proportionally. I'm going to post a suggestion that they add that info to the descriptions within the game.

Thanks everyone for your help!

faloun wrote:Koub, your explanation of how pollution is generated makes sense, but I wonder if that isn't more of a "developer" answer. From my (a player's) perspective, it seems strange that other modules have specific notes on how they affect pollution, where it's expected that you know electricity generates pollution proportionally. I'm going to post a suggestion that they add that info to the descriptions within the game.

The only module really adding pollution is the productivity, it explicitly increases pollution. With the speed module it's because of increased power usage. But i get what you mean, if you don't know the mechanics (pollution increases with power usage) you can easily get confused

In that case, the wiki is incorrect, since it only states that efficiency modules reduce power consumption and doesn't mention anything about pollution, whereas it makes it explicitly clear the speed and productivity modules not only increase power consumption but pollution as well.

Goldenslicer wrote: ↑

Sat Jul 27, 2019 8:14 pm

In that case, the wiki is incorrect, since it only states that efficiency modules reduce power consumption and doesn't mention anything about pollution, whereas it makes it explicitly clear the speed and productivity modules not only increase power consumption but pollution as well.

The pollution production is not explicit, but implicit. It's the consumption induced pollution is reduced, not the pollution in itself.
In other words :
Efficiency modules = less concumption => less pollution
Speed modules = more consumption => more pollution
Productivity modules = more pollution and more consumption => more pollution and even more pollution.

At least that's my understanding. If I'm wrong, then indeed the wiki is wrong too.

The general Modules page does explain that :
https://wiki.factorio.com/Module#Efficiency_module

I guess the issue is that while item consumption/production(&speed) is pretty visible, power use (especially electric) and pollution - isn't ?

BlueTemplar wrote: ↑

Sun Jul 28, 2019 9:00 am

I guess the issue is that while item consumption/production(&speed) is pretty visible, power use (especially electric) and pollution - isn't ?

My guess is that the issue is that this topic is four years old and thus very outdated about the state of the wiki.

Now that you mention it, I remember the initial necro, and the forgot about it

You really notice the less pollution when you put them in mining drills. On rare occasions I've done that to not agitate nearby biters. Makes them have a tiny pollution cloud that doesn't really spread beyond the outpost.

Huh, I thought that Goldenslicer's (recent) post referred to the individual wiki pages, but the pages for individual speed modules don't say anything about pollution...

Today I tested it (version: 2.0.9), and efficiency modules do reduce pollution directly, not only power usage!
See this image: