Electricity
Electricity is an electromagnetic phenomenon created by the interaction of particles present in matter that are positively or negatively charged and whose effects can be used to generate energy.
Matter is made up of atoms made up of a central nucleus formed of protons and neutrons. Protons have a positive charge and neutrons, as the name suggests, are neutral and have no charge. Around the nucleus of the atom gravitate several electrons which have a negative charge.
Normally, in an atom, the negative charge of the electrons and the positive charge of the protons are of the same magnitude. The atom is then electrically neutral. However, under certain conditions, an electron can leave the atom or be added to it.
Thus electrons can circulate in matter and create an electric current, or can accumulate in certain places and create static electricity.
Electricity can only be perceived through its effects, including certain natural manifestations such as lightning. Today, electricity is useful in every aspect of our daily lives. We use it to eat, move around, light up and take care of ourselves.
The electric current
An electric current is generated from the dynamic electricity. Electric charges move through a conductive material. Metals, salt water or the human body are good conductors. The current is said to be direct when the electrons move in a conductor in the same direction.
Alternating current is the movement of electrons that alternate between one direction and another. This to-and-fro movement of electrical charges is produced, among other things, by the rotation of an alternator.
An electric current is generated by the movement of electric charges in a conductive material. The current is said to be “direct” when electrons move in the same direction within this conductor and “alternating” when their movement alternates between one direction and another. Electricity is now used for lighting and heating, but also to power a growing number of electronic devices.
Electricity is difficult to store in large quantities and at affordable costs. This issue of storage is central to the development of intermittent renewable energies. Electric power is measured in watts (W) and its multiples (kW, MW, GW, TW) while a quantity of electricity produced or consumed during a given period is measured in watt-hours (Wh) or its multiples (kWh). , MWh, GWh, TWh).
Electricity storage
Electricity is difficult to store in sufficient quantity and at affordable costs to meet our energy needs. Direct solutions require “resistance-free” conductors called superconductors in which it is theoretically possible to circulate without loss the electricity that one wishes to store.
These materials currently available at very low temperatures of the order of a few degrees Kelvin are reserved for specific applications and for small quantities.
Indirect solutions only provide partial, expensive and often local solutions (storage batteries, Power to Gas, compressed air that is then expanded, water raised between two dams, etc.). Electricity production must therefore be continuous in order to meet current consumption.
However, electricity consumption varies according to the time of day. It is therefore necessary to be able to adjust the production of electricity to consumption.
electricity transmission
Electricity is transported easily and quickly. Power lines deliver electricity from the power station to the consumer areas. The transport of electricity on a national scale is mainly ensured in very high voltage at 400,000 volts via aerial lines called interconnection.
Opponents are coming forward more and more frequently to demand their disappearance from the visual field, which is always expensive and sometimes technically almost impossible. At regional or local level, transmission is provided at high voltage (mainly 225,000 and 63,000 volts) via lines which can be buried.
The use of very high voltage makes it possible to limit line losses due to the Joule effect (release of heat) or to electromagnetic effects (capacitive effects between the line and the ground). Energy losses in high voltage lines are proportional to the distances traveled by the electric current.
Electricity distribution
Distribution networks deliver electricity directly to end consumers. The power lines are at a voltage of 20,000 volts, increasing unit energy loss but over short distances. Transformer stations are placed at the interconnection of the transmission and distribution networks.
Certain means of decentralized electricity production (wind turbines, photovoltaic panels in private homes) can be directly connected to the distribution network and do not go through the transmission network. We talk about local production for this reason.
During the transmission and distribution of electricity, the current is most often three-phase. There are three conductor cables per circuit to optimize the flow of electricity and minimize line losses.
Electricity is a secondary energy or an energy carrier because it is generated from the transformation of a primary energy by means of a conversion system.
A primary energy is an energy directly available in nature such as fossil fuels, geothermal energy, solar radiation, wind or biomass. For example, the combustion of coal (primary energy) is used in a thermal power plant to produce electricity (secondary energy).
Electricity can only be perceived through its effects, including certain natural manifestations such as lightning. Today, electricity is useful in every aspect of our daily lives. We use it to eat, move around, light up and take care of ourselves.
Electricity is a secondary energy or an energy carrier because it is generated from the transformation of a primary energy by means of a conversion system. A primary energy is an energy directly available in nature such as fossil fuels, geothermal energy, solar radiation, wind or biomass.
For example, the combustion of coal (primary energy) is used in a thermal power plant to produce electricity (secondary energy).
