Editing Stationary engine (section)

=== Electricity generation ===

Before [[mains electricity]] and the formation of nationwide [[electrical grid|power grids]], stationary engines were widely used for [[small-scale electricity generation]]. While large [[power station]]s in cities used [[steam turbine]]s or high-speed reciprocating [[steam engine]]s, in rural areas [[gasoline|petrol/gasoline]], [[kerosene|paraffin/kerosene]], and [[fuel oil]]-powered internal combustion engines were cheaper to buy, install, and operate, since they could be started and stopped quickly to meet demand, left running unattended for long periods of time, and did not require a large dedicated engineering staff to operate and maintain. Due to their simplicity and economy, [[hot bulb engine]]s were popular for high-power applications until the [[diesel engine]] took their place from the 1920s. Smaller units were generally powered by spark-ignition engines, which were cheaper to buy and required less space to install.

Most engines of the late-19th and early-20th centuries ran at speeds too low to drive a [[dynamo]] or [[alternator]] directly. As with other equipment, the [[electrical generator|generator]] was driven off the engine's flywheel by a broad flat belt. The pulley on the generator was much smaller than the flywheel, providing the required 'gearing up' effect. Later spark-ignition engines developed from the 1920s could be directly coupled.

Up to the 1930s most rural houses in [[Europe]] and [[North America]] needed their own generating equipment if [[electric light]] was fitted. Engines would often be installed in a dedicated "engine house", which was usually an outbuilding separate from the main house to reduce the interference from the engine noise. The engine house would contain the engine, the generator, the necessary [[switchgear]] and [[electrical fuse|fuses]], as well as the engine's fuel supply and usually a dedicated workshop space with equipment to service and repair the engine. Wealthy households could afford to employ a dedicated engineer to maintain the equipment, but as the demand for electricity spread to smaller homes, manufacturers produced engines that required less maintenance and that did not need specialist training to operate.

Such generator sets were also used in industrial complexes and public buildings – anywhere where electricity was required but mains electricity was not available.

Most countries in the [[Western world]] completed large-scale rural electrification in the years following [[World War II]], making individual generating plants obsolete for front-line use. However, even in countries with a reliable mains supply, many buildings are still fitted with modern [[diesel generator]]s for emergency use, such as [[hospitals]] and [[pumping stations]]. This network of generators often forms a crucial part of the national electricity system's strategy for coping with periods of high demand.