Electricity

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 with which energy is generated or used. Its unit is a watt (W): one watt is the generation or consumption of one joule per second.

An electric current is the movement of electric charges. Electricity is produced by generators. Electricity is quite easy to transmit and can be converted into other forms of energy. Electrical energy is measured most commonly in kilowatt hours (kWh): 1 kWh = 3,600,000 J.

An electricity 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. A fuel´s thermal energy is used for developing the steam that makes the steam turbine run, which in turn makes the generator produce electricity.

Examples of means of creating electricity without the intermediate stage of mechanical energy include solar panels and fuel cells.

In a nuclear power plant, energy is obtained from the fission reaction of uranium nuclei. The heat produced by the nuclear reactor turns water into steam that rotates the turbine, which in turn rotates the generator. In Finland there are two nuclear power plants, one at Loviisa and the other at Olkiluoto in Eurajoki. Loviisa has two plant units in operation, one which came on stream in 1977 and the other in 1980. At Olkiluoto there are two units in operation: Olkiluoto 1 came on stream in 1978 and Olkiluoto 2 in 1980. Olkiluoto 3, a new unit, is under construction at Olkiluoto.

In uranium fuel, the energy is in compact form. One power plant unit at Olkiluoto produces about 7 TWh, or 7 billion kWh, of electricity per year while consuming about 20 tonnes of uranium fuel. To produce the same amount of electricity at a coal-fired plant would require almost two and half million tonnes of coal.