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Steel furnaces cause far more pollution than electric furnaces.

However, electric furnaces use up energy, and when I burn coal (or solid fuel) in boilers to power these, I am also causing pollution.

Assuming I am not using solar panels but only boilers and steam engines to power my ore industry, which one is the greener option per unit of ore smelted?

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Update for 0.17

Electric Furnace:

  • Pollution: 1/m
  • Power: 180 kW
  • Crafting Speed: 2

Steel Furnace:

  • Pollution: 4/m
  • Power: 90 kW
  • Crafting Speed: 2

Boiler:

  • Pollution: 30/m
  • Power: 1.8 MW

Now everything is 100% efficient. So to add in the additional pollution for power generation:

180kW * ( 30/m / 1800kW ) = 3.0/m

But you're also consuming an extra 90kW of fuel now, if you're using coal, mined with electric mining drills:

90kW * (1 coal / 4000kJ) * (0.5 s / 1 coal) * 10/m = 0.1125/m

This will of course also adds additional pollution for the electricity to mine, but it's only off by about 1%.

So added up The Electric Furnace = 1+3.0+0.1125=4.11125 /m compared to the Steel Furnace's 4 /m. So now the Electric Furnace slightly less environmentally friendly before adding any modules or using solar or nuclear power. A single level 1 efficiency module would make it more friendly however.

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31

Steel furnaces cause pollution but electric furnaces do not.

Firstly, this is not quite true. Electric furnaces do produce pollution, but only about a quarter of the amount steel furnaces do (0.9 pollution to 3.6, according to their linked wiki pages).

Electric furnaces use up 180kW of electrical energy. Steel furnaces use 180 kW of fuel energy. However, boilers have an efficiency of only 50%. They generate 390kW of heat energy for every 780 kW of fuel the burn, and in the process produce 6 pollution. Steam engines then convert the heat energy to electrical energy - I believe this is at 100% efficiency, but I'm not sure.

So the output from one boiler can power two electrical furnaces with 30kW to spare, and combined they produce (6 + 0.9 + 0.9) = 7.8 pollution. Two steel furnaces produce only 7.2 pollution, with nothing to spare.

Scale that up so you can use the excess power output from the boiler, and you have:

  • 6 boilers at 6 pollution each - 36 pollution
  • 13 electric furnaces at 0.9 pollution each - 11.7 pollution
  • Which makes 47.7 pollution in total

This compares with 13 steel furnaces at 3.6 pollution each, which makes 46.8 pollution in total.

Therefore: steel furnaces are greener than boiler-powered electrical furnaces.

Of course two other factors can come into play:

  • Solar power, which produces no pollution and uses no fuel (set up costs aside)
  • Modules. Electric furnaces can store two modules. These can be used to reduce the electricity consumed by the furnace to 20% (I think) of their standard usage. In this case 6 boilers could power 65 electric furnaces, producing 36 + (65 * 0.9)=94.5 pollution. Meanwhile 65 steel furnaces would produce 65 * 3.6 = 234 pollution - nearly two and a half times more.

Edit: As @MSalters points out, efficiency modules also reduce the pollution from the furnaces themselves, so polution is actually reduced to 36 + (65 * 0.9 * 0.2) = 47.7 pollution. That means steel furnaces pollute nearly five times more than this.

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  • 2
    Great answer- I think it's better written than mine. +1 from me
    – Comic Sans Seraphim
    Jun 23, 2016 at 17:28
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    I think you got your math a bit wrong. It looks like two steel furnaces should produce 7.2 pollution, not 7.8. The calculation for 13 steel furnaces looks fine.
    – user2357112
    Jun 23, 2016 at 19:26
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    Modules are the big differentiator. Even with the entry-level efficiency modules, you already have a 60% reduction (180 kW -> 72kW).But as an additional benefit, they also reduce direct pollution. Those 65 electric furnaces don't produce 65*0.9 pollution, they produce 65*0.9*0.2 = 11.7 pollution. This puts the total pollution including boilers at 47.7, which is about a fifth of the steel furnaces.
    – MSalters
    Jun 23, 2016 at 20:58
  • @user2357112 Herp derp. You're right, I'll edit.
    – raveturned
    Jun 23, 2016 at 21:28
  • @MSalters You're right too. Wiki page for Modules only mentions this towards the very end, so I missed this. I'll amend.
    – raveturned
    Jun 23, 2016 at 21:33
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A steel furnace produces 3.6 pollution.

An electric furnace produces 0.9 pollution, but also requires 180kW of electricity to work at full speed. Solar panels produce clean electricity but boilers and steam engines do not.

For the purposes of calculations, we will use the most efficient 1:14:10 pump:boiler:engine ratio.

A steam engine produces 510 kW of electricity from 1.4 boilers. The engine provides enough for 2.83 furnaces. If 2.83 furnaces require 1.4 boilers, we can assume there will be twice as many furnaces as boilers.

A boiler produces 6 pollution- 3 per furnace. This means that factoring in steam power generation, the electric furnace produces 3.9 pollution.

Note that this doesn't take into account mines or loaders involved.

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