Thermal energy is called energy released in the form of heat. It can also be called heat energy.
Heat energy can be obtained in several ways:
- of the nature. It would be the case of geothermal energy or solar thermal energy.
- from chemical energy,
- by an exothermic reaction, like the combustion of some fossil fuel.
- for a reaction of fission nuclear energy or nuclear fusion energy. By splitting the nucleus of an atom a large amount of heat is obtained.
- by electric energy by Joule effect or by thermoelectric effect
- by friction, as a residue of other mechanical or chemical processes.
The thermal energy can be transformed using a thermal engine, either in electrical energy, in a thermoelectric power station; or in mechanical work, such as in an automobile, airplane or ship engine.
Obtaining thermal energy can imply a certain environmental impact. If it is obtained through the combustion of fossil fuels, combustion releases carbon dioxide (CO2) and polluting emissions. Current technology in nuclear energy results in radioactive waste that must be controlled. In addition, the use of land from power generation plants and the risks of contamination due to accidents in the use of the materials involved, such as oil spills or petrochemical derivatives must be taken into account.
Conversion of thermal energy to other forms of energy
Thermal energy or heat energy can be converted to other types of energy. The main forms of energy conversion are conversion into mechanical energy and conversion to electrical energy.
Conversion of heat energy into mechanical energy
Heating a gas to a constant volume increases the average kinetic energy of the particles that make it up. At the same time, the heated gas increases the pressure on the walls of the container that contains them. At this moment the gas has acquired potential energy, at a macroscopic level, and thus it can, eventually, expand and be able to perform mechanical work as commonly happens in thermal machines such as thermal engines or steam engines.
The potential energy acquired by the gas is due to the thermal energy supplied to it. The acquisition of thermal energy by the gas is confirmed by the fact that the gas increases its temperature. If the gas can expand, it does a job and, therefore, consumes some of the energy it has acquired and cooled down.
Conversion of heat energy to electricity
Thermal energy can be transformed into other forms of energy, for example, it is transformed into electricity or electric power.
This conversion of thermal energy into mechanical energy is carried out in thermoelectric and thermonuclear power plants. The thermoelectric plants gas is heated by burning fossil fuels (usually coal or natural gas). In thermonuclear plants the gas is heated by the use of nuclear energy. They are also known as nuclear power plants. Both types of plants use steam in the energy conversion process.
Another type of plants capable of generating electricity are geothermal power plants and thermodynamic solar power plants. In these cases the thermal energy is obtained naturally. In geothermal energy heat is obtained from the interior of the Earth. In thermal solar energy the heat energy is obtained from solar radiation.
Thermal energy measurement unit
The units for measuring thermal energy are the same units that are used to measure energy since it is still a form of energy.
Energy is measured in Joules (J) according to the international system. Although when it comes to calorific energy calories are also commonly used (cal). A calorie is the amount of energy that is needed to raise one gram centigrade of water. A calorie equals 4.18 joules.
Last review: April 13, 2017