Energy and environment, wood and PELLET

How energy shows itself and has been used
For energy we mean "the system capacity to produce work". Without energy anything can happen. Also life and human activities depend strictly on energy available. Energy can shows itself in different forms; the most used by human are:

• mechanic energy
• electric energy
• chemical energy
• thermic energy

All forms of energy are convertible between them; for example, electric energy can be converted in thermic energy (functioning of the electric stove), mechanic energy can be converted in electric energy (hydroelectric station).
The fundamental laws of Physics impose limits in converting energy from a form to another. Heating is the form of energy most 'reducible' and it can't be totally transformed in richest forms.
There several unit measures for energy, and sometimes they can create mental confusion for the one who is not operating in energy. The official International System energy unit measurement is "Joule" (J), but the most used unit is "Kilowatt for hour" (kWh), equal to 3.600.000 J.