In thermal power stations, mechanical power is produced by a heat engine, which transforms thermal energy, often from combustion of a fuel, into rotational energy. Most thermal power plants produce steam, and these are sometimes called steam power plants. Not all thermal energy can be transformed to mechanical power, according to the second law of thermodynamics. Therefore, thermal power plants also produce low-temperature heat. If no use is found for the heat, it is lost to the environment. If reject heat is employed as useful heat, for industrial processes or district heating, the power plant is referred to as a cogeneration power plant or CHP (combined heat-and-power) plant.
South Sulawesi's installed electrical generating capacity in 2005 was 543.93 megawatts: 36.06% derived from hydroelectric (own by PLN), 13.96 from oil (own by PLN), 41% from natural gas (Independence Power Producer/IPP), 7.90% from oil (IPP), 1.04% from oil (small-generation). Installed capacity is the amount of power that could be generated at a given instant if all power plants were working simultaneously at full capacity.
Actual production depends on the amount of time particular generators are running and on load (appliances, motors, etc) placed on the system. Electric Utilities build 10% extra capacity into their systems, above the expected maximum load, to