100W per adjacent lava block
Essentially a Heat Generator is a geothermal generator that utilizes heat from adjacent lava blocks (flowing or source) in order to generate electricity. Each generator can store 160.0 kJ worth of energy on its own. For every lava source block placed next to or on the Heat Generator, the power output will raise 100 watts (100 joules/s). Buckets of lava, or coal may also be placed in the generator to temporarily boost energy output by 2000 watts. When using buckets of lava, the bucket remains in the input slot.
The maximum non boosted power output of a heat generator is 500W; 5 sides of the generator must be touching lava, with the back face plugged into some form of wiring.