Energy can be defined as the ability to do work. Kinetic energy, heat, and electricity are particular forms of energy.
The basic energy unit is a joule (J). Power means the speed at which energy is generated or used. The unit of power is the watt (W): one watt is the generation or consumption of one joule of energy in one second.
An electric current is the movement of electrical charges. Electrical energy is most commonly measured in kilowatt hours (kWh): 1 kWh = 3,600,000 J.
A generator converts mechanical energy into electrical energy. A generator can run on wind or hydropower, but most of the electricity in Finland originates from thermal energy created with fuels such as coal, wood, peat, natural gas, or uranium. Electricity can also be created without the intermediate stage of mechanical energy; examples include solar panels and fuel cells.
The national grid and local distribution grids transfer the electricity from the power plant to homes and industrial facilities.