But what if efficiency modules had a pollution modifier?
- Eff1: -25% consumption, -10% pollution
- Eff2: -40% consumption, -15% pollution
- Eff3: -50% consumption, -30% pollution
Why -consumption is uninteresting:
The maths is too simple. You can just calculate how much energy is saved in a machine, for example 150kW * 0.3 = 45kW, and you can compare it with clean electricity: for example a solar panel produces 42kW on average. So an eff1 module in assembler 2, is roughly as effective as building a new solar panel. Which is cheaper? Well they are pretty similar, but the solar panel is more iron-rich, while the eff module is copper and oil rich, but basically a watt saved by an eff module in an assembler 3 tends to be a little cheaper than a watt generated by a solar panel.
Of course this become a big problem with the eff2/eff3, because it becomes "I'm spending HOW MUCH to save 60kW?!!!!!" and even if the -consumption numbers are made a lot bigger (like -160%) it's still not really an interesting choice - and the big numbers would look silly, like "-160% consumption, maximum -80%".
-pollution may not be cost effective... but at least it's interesting
Say it's pretty easy - by using the very expensive eff3 modules - to get a -80% pollution modifier in beacon setups and dramatically slash the pollution created by prod+speed beacon setups - this would involve replacing 200% of the speed bonus with a -120% pollution modifier (and a largely irrelevant -160% consumption). In a strict cost analysis it's probably going to work out much cheaper to build more laser turrets and just destroy the enraged biters. But at least it's an interesting choice, rather than spending 10x as much to save a kW as it takes to generate a kW (a choice you will only make if you've either not done the maths, or are daft), it's the choice between running a dirty factory with a "burn the biters!" attitude, or a clean factory with consideration for the biters. And again, running a clean factory might be stupid because biters are pretty easy to deal with by genocide, but it can be a fun choice to make, and if the higher tier eff modules had a potent pollution reducing effect it would make more options for running a clean factory - instead of only using "eff1 spam" type setups, you could use prod+speed beacons with a cost-effectiveness hit, but being cleaner by reducing the factory footprint thanks to the +40% productivity.