Just a good guideline when it comes to factories and power plants:
You can start building factories as soon as you complete the assembly line. Although it’s pretty late in the game, it is highly recommended if you want to produce things in your city faster. Alone, a factory gives +25% productivity. With power through one of the three power plants, you get an additional +50% productivity. With a forge, you can have up to +100% productivity in a city. Add this with some productive resources like aluminum, iron, coal, or copper, and daaaaamn! How about with Ironworks? Production would practically skyrocket to around +200% if you have both coal and iron for it!
There are four ways to get power in your city:
1. Coal Plant – Let it be known that even though you can build a coal plant without coal, you do need coal for power. However, along with a factory, this brings a total of +3 unhealthiness. That’s not good, so try to counteract that with aqueducts (with Masonry, Mathematics) and hospitals (with Medicine). I actually recommend this if you also focus your research on Ecology, which then you can build recycling plants. Recycling plants eliminate all unhealthiness caused by buildings. Ultimately, a coal plant will have the features of a hydro plant, but only eventually.
2. Nuclear Plant – A nuclear plant requires uranium to give power. Although it doesn’t give off unhealthiness, it has a small chance of a nuclear meltdown. It says “small”, but personally in due time a nuclear meltdown will occur, but that’s if you play for quite a long time. If you’re close to year 2050 (for a time victory), I doubt a nuclear meltdown will happen so soon. But if you’re trying to withstand the test of time, avoid this and just go with a coal plant or hydro plant.
3. Hydro Plant – Obviously, the best of the three. The only drawback is that you can only build this in cities next to a river, not the ocean. If your city can build a hydro plant, be sure to pick this out of all three because it is clean and doesn’t cause a nuclear meltdown.
Now, above all else for the +50% productivity, there is a world wonder that also gives power:
4. The Three Gorges Dam – You can start building this as soon as you build plastics (Plastics can be built after Industrialism). This world wonder gives power to all cities on the continent that it is built on. So, only build it on the continent where you have the most cities for maximum effect! If you have 6 or so cities on a continent, just rush for this so you don’t have to waste turns making power plants for every one! You should think of this as a priority when you’re playing on a single continent, such as Pangaea and Great Plains.Discuss this article on the forum