The heat generator produces energy from lava beneath it or from a lava bucket or coal inserted in the left slot, which is much like a geothermal generator from IndustrialCraft. Each generator can hold about 160.0 kJ worth of energy on its own.
It produces: 13.33 Amps, 120 Volts and 1.6 KiloWattsSince it does not use steel in its crafting recipe, it may be the best starting generator. However, it does have disadvantages; you must find lava first, which is dangerous, and the lava may spawn fireballs if placed under.
One lava bucket provides 200 kJ of energy when placed inside the generator.
The heat generator will commonly take around 8-10 minutes for it to reach maximum power output.