Understanding Energy Sources and Electric Power Plants
Energy Sources and Their Uses
The energy we consume serves both household and industrial purposes. Energy sources are natural resources from which we obtain different forms of energy that can be transformed for specific uses.
Electricity: The Dominant Energy Form
Electricity is the most widely used form of energy in industrialized societies because:
- It can be transformed into other forms of energy.
- It can be transported long distances inexpensively.
Electric Power Plants: Transforming Energy
Electric power plants are facilities where primary or secondary energy is transformed into electricity. These plants use an external source of energy to produce electricity and typically have a turbine alternator system.
The turbine converts mechanical energy into the rotating movement of a shaft. The alternator has a fixed part called the stator and a moving part called the rotor, connected to the turbine shaft. As the rotor shaft moves, alternating electrical current is produced on each of the stator’s coils.
Transporting Electricity
Transport of electricity is crucial because electric power plants are usually located far away from the points where the energy is used. Electricity cannot be stored, so it must be transported. This transport involves several processes:
- Increasing voltage to 220,000V or 400,000V.
- Transporting it via high-voltage cables attached to towers.
- Decreasing the voltage at electricity substations to 3-30 kV.
- Distribution to different locations, with 230-240V.
Types of Electric Power Plants
Nuclear Power Plants
This type of plant includes a nuclear fission reactor that produces the steam needed to move the turbine rotor. Uranium is the main fuel used. Uranium fission is the basic process to produce energy in nuclear power plants. When fission takes place, a lot of energy, previously used to hold the atom together, is released. The fission takes place in the reactor. The electrons are responsible for creating the electricity as well as creating chemical energy. From this nucleus, we can obtain nuclear energy.
Fossil Fuel Thermal Power Plants
Water is heated in a boiler (a tank where water can be heated to its boiling point of 100°C) by the heat generated from the combustion of a fossil fuel. The steam that is generated moves the turbine connected to the generator.
Combined Cycle Power Plants
Electricity is generated as a result of two combined cycles: a cycle that uses air and gas, and a conventional thermal cycle. During the first cycle, a gas turbine is used that includes a compressor. Air is mixed with the gas and burned, which generates electricity in the turbine-generator system. The combustion gases are transported to a boiler where they transfer their energy to the water during the second cycle.
Hydroelectric Power Plants
These plants use the potential energy provided by the height of stored water in a dam, converting it into kinetic energy. This energy moves the blades of the turbine. Depending on the destination of the water, there are two types:
- Gravity-driven: Water used follows the course of a river and will not be reused.
- Pump-driven hydraulic power plants: Water descends to a reservoir located at a lower height, then pumped to a higher reservoir to reuse it.
Solar Power Plants
These plants use the energy from the sun.
Photo-thermal Power Plants
The heat generated by solar radiation produces steam that is used to move the rotor in the generator. They use heliostats that reflect sunlight and concentrate it at one point where it reaches a high temperature.