The energy produced is classified according to the sources used, the one generated by the exploitation of non-renewable sources, such as oil, coal and natural gas, is considered "Traditional".
Involuntary combustion of these substances can represent a high risk of explosion.
The thermoelectric plants were the first types of plants in use. In them, a fuel (derivatives of oil, coal or gas, waste) is burned in order to develop heat; this heat is transmitted to a boiler, in which high pressure water circulates which is thus transformed into steam, useful for operating the turbine.
These plants have a strong environmental impact due to emissions to air and residues, in particular coal-fired plants and, to a lesser extent, other types of plants (oil and waste) and, even less, in gas-fired plants.