Technological Methods of Generating Electricity

Technological systems designed by humans serve different needs in modern life. They usually require electrical energy to operate.

With the help of different technological systems, energy is transformed into electricity and then transferred through an electrical grid to households. To use it, it is usually sufficient to plug an appliance into an electrical outlet.

The following table presents different technological systems used for generating electricity, the energy resource(s) they use and their origin.

The majority of systems that generate electricity use a turbine-generator unit.

The role of the turbine-generator unit is to transform the mechanical energy of a moving fluid into electricity. This transformation takes place in the following way:

1. The turbine is driven in a rotational motion by the mechanical energy of a moving fluid (e.g. steam, waterfall, wind).

2. The rotor linked to the turbine undergoes a rotational motion, while the stator is stationary.

3. The interaction between the rotor (mobile) and the stator (stationary) generates an electrical current through electromagnetic induction.

A thermal power plant transforms the chemical energy contained in fossil fuels into electricity. For example, coal-fired power stations use coal as the source of chemical energy. The following sequence of transformations occurs:

Fossil energy (chemical energy) → Thermal energy → Mechanical energy → Electrical energy

A thermal power plant involves many processes and subsystems, including one or more steam-driven turbine-generator units. The following diagram and table describe how electricity is generated at a coal-fired power station.

A nuclear power plant transforms the nuclear energy contained in the nucleus of heavy isotope atoms extracted from the lithosphere (e.g., uranium and plutonium) into electricity in the following sequence of transformations:

Nuclear energy → Thermal energy → Mechanical energy → Electrical energy

In the reactor of a nuclear power plant, uranium and/or plutonium pellets are contained in long rods.

A nuclear power plant involves many processes and subsystems, including one or more steam-driven turbine-generator units. The following diagram and table describe how electricity is generated at a nuclear power plant.

A geothermal power plant transforms thermal energy from the lithosphere into electricity in the following sequence of transformations:

Geothermal energy (thermal energy) → Mechanical energy → Electrical energy

There are different ways to generate electricity using the Earth's internal heat. The method discussed in this concept sheet is based on pumping hot groundwater from a saturated zone, sometimes called a phreatic zone, below the water table. The saturated zone is a layer of rock and soil where the gaps between them are completely saturated with water.

A geothermal power plant involves many processes and subsystems, including one or more steam-driven turbine-generator units. The following diagram and table describe how electricity is generated at a geothermal power plant.

A hydroelectric power plant coupled with a reservoir transforms mechanical energy into electricity by taking advantage of the position and speed of water in the following sequence of transformations:

Hydraulic energy → Mechanical energy → Electrical energy

A hydroelectric power plant involves many processes and subsystems, including one or more steam-driven turbine-generator units. The following diagram and table describe how electricity is generated at a reservoir-type hydroelectric power plant.

A wind turbine, either on its own or as part of a wind farm, transforms the mechanical energy of the wind into electricity in the following sequence.

Wind energy → Mechanical energy → Electrical energy

Several processes take place in such a set-up, including the use of a turbine-generator unit driven by the wind. The following diagram and table describe how electricity is generated by a wind turbine.

A photovoltaic panel, commonly called a solar panel, transforms the sun's radiant energy into electricity in the following transformation:

Radiant energy → Electrical energy

A photovoltaic panel uses silicon-based |(\text{Si})| photovoltaic cells. This metalloid element is a semiconductor that has the property of releasing electrons when exposed to sunlight. The following diagram and table describe how electricity is generated by a photovoltaic panel.