An Electrical Generator produces 3 electricity per second. Generators can only be built on a geyser, and only if you control at least one lightning rod. You can upgrade your Generators up to three times, with each upgrade increasing its electrical output by 2 electricity per second. Thus, when upgraded once it produces 5 electricity per second, when upgraded twice it produces 7 electricity per second, and when upgraded three times it produces 9 electricity per second. There is a research at the Research Clinic that allows additional generation as well.