Electrical power is the free flow of electrons. Power in turn is the conversion of energy to do work and the rate that the work is done. Thus electrical power is the rate at which energy is transferred through a circuit. Yhe unit is kWh (W is capitalized as it was named after a person, James Watt) or kilowatt (1000 Watts) hours. Horse power is the output of an engine over time. Most countries use the SI or international standard for measurement based on the metric system. In Europe, horsepower is expressed in watts.
A prime mover is an initial natural or mechanical source of power. Natural sources are water turbines and windmills. Your car’s engine is a ‘prime mover’. To generate electrical power you need a prime mover heading the power train. In nuclear, coal, oil or natural gas plants it is the steam turbine. Water is heated and converted to steam and forced through a turbine with multiple blades that are turned by the steam passing through them. Steam turbines are the primary means for producing electricity and are also the prime motive power for ships. Gas turbines are stationary jet engines, usually modified to run on diesel fuel or kerosene that operates similar to a steam turbine. The high energy and high speed gases pass from the jets exhaust and is coupled to the turbine, which powers the generator.
Solar Power Facts
In solar systems the sun’s ultraviolet light is used and the earth receives upwards of 174,000 trillion watts (terawatts) a day. About 30% of this is reflected back into space. This energy is what heats the earth and drives our weather, and it is free and clean. If it could be captured it would solve many of our power and pollution problems. Electrical production uses photovoltaic that converts light (UV or ultraviolet light) directly into electricity. Most photovoltaic cells run about 20% efficiency, but some in the lab stage can reach 40% conversion. These systems use inverters to convert the DC electrical current generated to AC electrical current for household use.
Diesel Generator Working Principle at Power Substations
Power substations utilize gasoline or diesel reciprocating engines, with diesel being the primary choice used in large scale electrical power production. Many portable generator units run on gasoline but these are small scale systems. Diesel engines are more efficient producing more power per mass of fuel burned than do gas engines. For large scale electrical production diesel is the choice. Portable high output units in the 480 to 640 kW range are diesel powered. Electrical power production depends on a mechanical source of power that powers a generator which in turn produces the electrical current. With exception of electronic photovoltaic power production, most electrical is powered by some mechanical input device.
How AC (Alternating Current) Works
Power in the US is produced at 60 Hz (Hertz) or cycles per second. As the generator/alternator runs, the current reverses, this is alternating current or AC as we refer to it. This repetitive oscillation is depicted by a mathematical curve labeled a sine wave. Most of us have seen a graphical representation of this and it appears as squiggly lines or a wave. Household electronics and electrical devices depend on this sine wave to time functions and it is necessary to produce a stable wave for electronic power converters that convert the AC to DC. Variations can cause damage to AC units, appliances and electronics. Also all sources have to synchronize as not to cause line failure in the electrical grid. This constitutes the introductory material in power generation; Part 2 “Making Power-Nuts and Bolts” will be addressed in next weeks blog!