Electricity production

electricity

While most of us probably take it for granted, energy does indeed play an integral role in our daily lives – in our homes, our cars, our places of work and our industries. Of course, we use different kinds of energy for different purposes. Most of the petroleum we consume is used in the transportation sector, including fuel for our cars but also planes, commercial trucks and mass transit. Heating, cooling and electricity for our homes come mostly from natural gas and coal; the same goes for businesses, too. Industry and manufacturing consume close to one-third of the nation’s total energy supply, mostly derived from fossil fuels.

electricity2

 

Electricity generation

Electricity generation is the process of creating electricity from other forms of energy.

The fundamental principles of electricity generation were discovered during the 1820's and early 1830's by the British scientist Michael Faraday. His basic method is still used today: electricity is generated by the movement of a loop of wire, or disc of copper between the poles of a magnet. [1]

For electric utilities, it is the first process in the delivery of electricity to consumers. The other processes, electric power transmission, electricity distribution, and electrical power storage and recovery using pumped storage methods are normally carried out by the electrical power industry.

Electricity is most often generated at a power station by electromechanical 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 such as solar photovoltaics and geothermal power.

Methods of generating electricity

There are seven fundamental methods of directly transforming other forms of energy into electrical energy:

  • Static electricity, from the physical separation and transport of charge (examples: triboelectric effect and lightning)
  • Electromagnetic induction, where an electrical generator, dynamo or alternator transforms kinetic energy (energy of motion) into electricity
  • Electrochemistry, the direct transformation of chemical energy into electricity, as in a battery, fuel cell or nerve impulse
  • Photoelectric effect, the transformation of light into electrical energy, as in solar cells
  • Thermoelectric effect, direct conversion of temperature differences to electricity, as in thermocouples and thermopiles
  • Piezoelectric effect, from the mechanical strain of electrically anisotropic molecules or crystals
  • Nuclear transformation, the creation and acceleration of charged particles (examples: betavoltaics or alpha particle emission)

Static electricity was the first form discovered and investigated, and the electrostatic generator is still used even in modern devices such as the Van de Graaff generator and MHD generators. Electrons are mechanically separated and transported to increase their electric potential.

Almost all commercial electrical generation is done using electromagnetic induction, in which mechanical energy forces an electrical generator to rotate. There are many different methods of developing the mechanical energy, including heat engines, hydro, wind and tidal power.

The direct conversion of nuclear energy to electricity by beta decay is used only on a small scale. In a full-size nuclear power plant, the heat of a nuclear reaction is used to run a heat engine. This drives a generator, which converts mechanical energy into electricity by magnetic induction.

Most electric generation is driven by heat engines. The combustion of fossil fuels supplies most of the heat to these engines, with a significant fraction from nuclear fission and some from renewable sources. The modern steam turbine invented by Sir Charles Parsons in 1884 - today generates about 80 percent of the electric power in the world using a variety of heat sources.

Other generation methods
Wind-powered turbines usually provide electrical generation in conjunction with other methods of producing power.

Various other technologies have been studied and developed for power generation. Solid-state generation (without moving parts) is of particular interest in portable applications. This area is largely dominated by thermoelectric (TE) devices, though thermionic (TI) and thermophotovoltaic (TPV) systems have been developed as well. Typically, TE devices are used at lower temperatures than TI and TPV systems. Piezoelectric devices are used for power generation from mechanical strain, particularly in power harvesting. Betavoltaics are another type of solid-state power generator which produces electricity from radioactive decay. Fluid-based magnetohydrodynamic (MHD) power generation has been studied as a method for extracting electrical power from nuclear reactors and also from more conventional fuel combustion systems. Osmotic power finally is another possibility at places where salt and sweet water merges (eg deltas, ...)

Electrochemical electricity generation is also important in portable and mobile applications. Currently, most electrochemical power comes from closed electrochemical cells ("batteries") [7], which are arguably utilized more as storage systems than generation systems, but open electrochemical systems, known as fuel cells, have been undergoing a great deal of research and development in the last few years. Fuel cells can be used to extract power either from natural fuels or from synthesized fuels (mainly electrolytic hydrogen) and so can be viewed as either generation systems or storage systems depending on their use.

Uses of Electricity

Massachusetts residents use energy to light, heat, and cool our homes and buildings, cook our food, wash our clothes, provide entertainment, and power our transportation. How much electricity and other energy do we need to provide these things in Massachusetts?

The answer to this question depends on whether we look at energy use as a whole or electricity use in particular. Because generating technologies can broadly be divided between those that produce electricity and those that produce other forms of energy, understanding the breakdown of electricity and energy use can help in understanding where clean energy and energy efficiency can be most effective.

Energy and electricity use can be divided into four main categories: Residential, Commercial, Industrial, and Transportation. Each area presents significant energy needs and significant oppurtunities for clean energy and energy efficiency.

 
 
 
 
     

Copyright 2005 ESD Bulgaria. All rights reserved.