A source of primary energy is a form of energy available in the Nature before any transformation. If it is not usable directly, it must be transformed into a secondary energy source to be implemented. In the industry of energy, one distinguishes the production from primary energy, his storage and his transport in the secondary form of energy, and the consumption of final energy.
The derived energy it is even transformed into final energy with the stage of use. Thus the mechanical energy of a water fall, transformed into electricity then transported in this form can it produce in the end user of electrical energy for various uses (lighting, cold, heating,…). Let us note that on the level of the user the forms of energy are more or less substitutable.
This series of transformations forms an energy chain, for example the oil chain: extraction, transport, refining, distribution, use. The transformations are characterized by an output, always lower than 1 in consequence of the losses.
In the statistics of comparison of the production and energy utilization, one with the practice to regard as primary energy, the energy which results from the first transformation (thus nuclear heat, wind electricity or hydraulic electricity it is regarded as primary electricity) and as final energy the form in which it arrives in the end user (thus electricity measured at the meter of the subscriber whatever of it is the final use: lighting, heating, machines…), because it is those for which one has statistical data.
To allow the comparisons, all the forms of energy are expressed using a common unit: the Ton equivalent-oil or Mtoe.
The primary forms of energy are the following ones:
- animal Human energy and : mechanical energy of animal haulage
- mechanical Energy of the natural elements:
- Hydraulic power (river and water falls) transform in mechanical energy (water mills) or electric (Hydroelectric station).
- tidal Energy (tides) transform in electrical energy in tidal power stations.
- Wind energy (wind) transform in mechanical energy (windmills, sailing ships, Sand yacht) or electric (wind generator ).
- chemical Energy: transform in heat (thermal energy) by Combustion, then in electricity.
- Combustible S minerals:
- Combustible solid minerals (CMS): coal, Lignite, containing more or less pure carbon.
- Hydrocarbon S: Natural gas, Oil (formed hydrogen and carbon molecules).
- Explosive S: not controlled energy.
- Biomass: Wood, products and vegetation wastes, formed of Organic matter (primarily carbon, hydrogen and oxygen), transformed into various fuels: wood and derived, Diester, Methane (biogas), methanol, ethanol…
- Nuclear energy:
- Fission: Radioactivity of the Uranium and plutonium transformed into heat, then in electricity; part of heat is lost and rejected into the air and water.
- Fusion: still at the experimental stage.
- Solar energy: solar radiation, transformed into heat (Solar-fired heater, Heat pump) or into electricity (photovoltaic cells).
- terrestrial thermal Energy:
- Geothermics: exploitation of the natural heat of the deep layers of the Earth's crust.
The forms of final energy are also varied:
- mechanical Energy: engines and machines (domestic industry, agriculture, transport, uses…)
- Electrical energy: lighting, cold, engines, heating,…
- thermal Energy: industry, agriculture, heating, refrigeration, air-conditioning…
- radiant Energy: lighting, emissions radioelectric (radio, television, telephony, Radar S, Laser S, x-rays…)
Let us note that the fuels, coal, oil, natural gas, have also a nonenergy use as raw material in chemical industry: Coal-chemical industry, Petrochemistry, Manure and the building or the Public works (Bitumen)…
See too
- Renewable energy
- Consumption of energy
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