Electricity generation is the process of converting some form of energy into electricity. For electric utilities, it is the first process in the delivery of electricity to consumers. The other processes are electric power transmission and electricity distribution which are normally carried out by the electrical power industry. Electricity is most often generated by electro-mechanical generators, primarily driven by heat engines fueled by chemical combustion or nuclear fission but also by other means such as the kinetic energy of flowing water and wind. There are many other technologies that can be and are used to generate electricity though, with solar photovoltaics being the most significant alternative currently.
Engine-generator
An engine-generator is the combination of an electrical generator and an engine (prime mover) mounted together to form a single piece of equipment. This combination is also called an engine-generator set or a gen-set. In many contexts, the engine is taken for granted and the combined unit is simply called a generator.
In addition to the engine and generator, engine-generators generally include a fuel tank, an engine speed regulator and a generator voltage regulator, cooling and exhaust systems, and lubrication system. Units larger than about 1 kW rating have a battery and electric starter; very large units may start with compressed air. Standby power generating units often include an automatic starting system and a transfer switch to disconnect the load from the utility power source and connect it to the generator.
Engine-generators are used to supply electrical power in places where utility (central station) power is not available, or where power is needed only temporarily. Small generators are sometimes used to supply power tools at construction sites. Trailer-mounted generators supply power for temporary installations of lighting, sound amplification systems, amusement rides etc.
Standby power generators are permanently installed and kept ready to supply power to critical loads during temporary interruptions of the utility power supply. Hospitals, communications service installations, data processing centers, sewage pumping stations and many other important facilities are equipped with standby power generators.
Privately-owned generators are especially popular in countries where grid power is undependable or unavailable. As in South Africa where we are experiencing elcectricity supply problems. Trailer-mounted generators can be towed to disaster areas where grid power has been temporarily disrupted.
The generator voltage (volts), frequency (Hz) and power (watts) ratings are selected to suit the load that will be connected.
Engine-generators are available in a wide range of power ratings. These include small, hand-portable units that can supply several hundred watts of power, hand-cart mounted units, that can supply several thousand watts and stationary or trailer-mounted units that can supply over a million watts. The smaller units tend to use petrol as a fuel, and the larger ones have various fuel types, including diesel, natural gas and propane (liquid or gas). The engine can also operate on diesel and gas simultaneously (bi-fuel operation).
There are only a few portable three-phase generator models available in SA. Most of the portable units available are single phase power only and most of the three-phase generators manufactured are large industrial type generators.
Portable engine-generators may require an external power conditioner to safely operate some types of electronic equipment. Small portable generators may use an inverter. Inverter models can run at slower RPMs to generate the power that is necessary, thus reducing the noise of the engine and making it more fuel-efficient. Inverter generators are best to power sensitive electronic devices such as computers and lights that use a ballast.