A diesel generator is a device or machine that uses a mechanical energy source to produce electricity using electromagnetic induction. In this case, mechanical energy source is diesel.
The engine owes its origin to Michael Faraday’s invention of electromagnetic induction and Rudolf Diesel’s engine (Ferguson, 1986, p.37).
Diesel engine was discovered in 1892 by Rudolf Diesel but his first operational engine was produced in 1897 with an efficiency of 75% using bio-fuel from pea-nuts.
There are two types of an internal combustion engines: Compression ignition (CI) engine and Spark ignition (SI) engine. The compression ignition (CI) engine is also referred to as diesel engine while the Spark ignition (SI) engine is also called a gasoline engine. The major difference between the two engines regards their mode of ignition. In a diesel engine fuel and gas are mixed in the cylinder before ignition while in a spark engine fuel is mixed external to the cylinder before ignition.
In diesel engines fuel is exposed to a highly compressed gas with high temperatures which auto-ignites it (Stone, 1985, p.11). Diesel Generator produces electricity by use of diesel as the initial energy source. Michael Faraday discovered the electromagnetic induction principle in 1831 which led to the development of today’s generator. He demonstrated a simple concept of the generation of an electric current in a conductor by the effects of current flow in an adjacent conductor (Duffin, 1990, p. 213). The concept; termed electromagnetic effect formed the basis of the first electrical the transformer.
The coupling of diesel engine and Maxwell’s generator formed the diesel generator. Early Diesel’s design suffered limitations due too its large size and weight which restricted it too heavy industrial applications such as powering pipelines and electric plants. Its later modifications increased its scope of application to powering small domestic loads.
Today there is wide domestic and industrial application of diesel generators. Regarding industrial application the generator is used as a source of backup power in the event of an outage of hydro (or nuclear, thermal, wind and Geothermal) power from the grid. Even hydropower generation companies that form the bulk work of the world’s electricity source have diesel generators for power supply in the event of system failure to allow the uninterruptable power supply to the industry. Despite its popularity, the generator produces a lot of noise. However; this noise has been reduced greatly through technological advances such as the use of noise dampers which also has achieved a high fuel economy and low cost of maintenance.
Regarding the generator’s efficiency, there have been many measures undertaken to improve it. For instance, turbocharging and supercharging technology has been used to enhance a high tolerance to boost since it is not subject to “engine knock” (Ferguson, 1986, p.37).
Turbocharging an engine increases its power output by increasing air entry in the cylinders which allows more diesel to be burned hence producing more power. Turbocharging improves the efficiency of the generator by improving its diesel consumption.
Also a lot of smoke (both cold and hot) produced by diesel engines when running on overload at high speed has been reduced by raising the compression ratio and cetane rating of diesel (Edward, 1973, p.236). High compression ratio and cetane rating improve internal engine combustion which reduces the carbon content in exhaust products. This has improved the diesel generator’s efficiency and improved fuel economy.
Another measure employed to improve efficiency is the use of magnets along fuel capillary lines. The magnets trap all the metallic impurities along the fuels passages in the engine allowing combustion of pure diesel with a higher power output than impure diesel which burns partially resulting in production of less power and a lot of smoke.
There is an expected increase in the use of diesel generator in future because of its increasing efficiency due to technological modifications such as reduction in size and increased portability. Its wider application will also be caused by easy substitutability of fossil diesel with other forms of fuel such as bio-fuels from vegetable oils. Another indicator of increasing the popularity of diesel generator is reduction in hydro power which will be caused by shrinkage of rivers due to global warming.This will leave diesel generators as the most available source of electricity.
References
Duffin, W.J. (1990). Electricity and Magnetism (4th ed.). London: McGRAW-HILL BOOK COMPANY.
Edward, F. (1973). Internal combustion engines and air pollution. New York: Harper & Row, publishers.
Ferguson, C. (1986). Internal combustion engines: Applied thermodynamics. Colorado: John Wiley & Sons.
Stone, R. (1985). Introduction to internal combustion engines. London: Macmillan.