Really-Early-Game(0-80 RF/t): Stirling Generator, Combustion Engine, Clockwork Engine, Hobbyist's Steam Engine, Survivalist Generator
Earlygame(80-500 RF/t): Big Reactors, Magmatic Dynamo, Combustion Generator(with Jet Fuel)
Midgame(500-10000 RF/t): Big Reactors, Endergenic Generator, Potion...