THERMAL ENERGY | Concept, technical details and features

Thermal energy is also known as caloric or calorific energy and is manifested through heat . It can be measured in Joules, as is often done with other kinds of energy, or it can be expressed in calories.

One calorie is equal to 4.18 Joules and is the amount of heat needed to increase the temperature of one gram of water by one degree (+1ºC) .

Heat energy is closely related to the temperature of a body or a system and to the kinetic and potential energy accumulated by the particles involved.

What is thermical energy?

Thermal energy can be defined as that which is released by a system in the form of heat . This passes from a hotter body to another that has less heat. It is the manifestation of the energy that a system possesses internally, which is a form of accumulated kinetic energy .

It is directly related to the temperature exhibited by the system. So, the more heat is introduced, the higher the temperature until a phase change is reached . In the case of water in a liquid state , until it passes into a gaseous state in the form of steam. Heat energy can be transformed into mechanical energy or electrical energy .

How does thermal energy work?

Heat energy is the expression of the internal energy of a body and affects the movement of the particles that make it up . As a body gains heat, the internal motion of the particles increases and they become more unstable. The opposite also occurs: When the body loses heat, the particles will progressively stop until they stabilize.


  • RADIATION : In this case the heat is displaced in the form of electromagnetic waves. An example of this is solar energy through solar panels . It also happens when the heating is turned on: The air is radiated with heat and the temperature rises.
  • CONDUCTION : This is when a warmer body comes into contact with a cooler or less heated one. In this way the heat is transmitted and the temperatures are equalized. This cannot happen when the initial temperature is the same.
  • CONVECTION : It is the displacement of particles that are hot in a medium that is colder. This happens with the wind: The moving air containing hot particles causes it to be perceived as hot air.

Characteristics of thermal energy

  • It is a manifestation of the internal energy of bodies or systems.
  • It can be transmitted from one body to another or one system to another.
  • As the heat increases, the body temperature rises.
  • It can be obtained from various sources .
  • It has the ability to turn into other kinds of energy .
Solar Heater – Slight tilt, pointing E looking for the sun.

How is thermal energy obtained?

It can be obtained from nature, from the Sun, by exothermic reaction such as combustion , etc. Nuclear reactions also emit heat, it can be by fission (nuclear division) or fusion (union of nuclei). Another way to obtain heat is through the Joule effect, which is a phenomenon that occurs when electric current circulates in a conductor. Part of the energy of movement of the electrons is transformed into heat by the collision it has with the atoms of the conducting material.

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On the other hand, you can also take advantage of heat energy directly from nature, as is the case with geothermal energy , which involves taking advantage of the heat that is inside the earth. Photovoltaic energy is another thermal energy that can be used directly from the sun’s rays.

Examples of thermal or heat energy

  • Boiling water: When heat from a flame is introduced into a container of water, the temperature rises by increasing the internal energy of the system. This causes the water to change phase (evaporate). The same happens if it is in a solid state (ice), because when it is removed from the freezer, the heat in the environment radiates the ice until it becomes a liquid again.
  • Chimneys: In a chimney there is a constant combustion reaction of an organic matter: firewood. In this way the heat energy of the fire radiates the room keeping the house warm.
  • Heaters:  They keep the water at a comfortable temperature. The electric ones work with a metal resistance group that transforms electrical energy into thermal energy, increasing the temperature of the water to the desired level.
  • The Sun: The largest source of thermal energy is the Sun, which is constantly burning, radiating enormous amounts of heat and light. Living beings take advantage of this source of energy, for example, by exposing themselves to sunlight to heat up.
  • Nuclear energy : Atomic bombs and nuclear reactions in general trigger a series of atomic chain reactions that generate enormous amounts of heat.
  • Homemade thermos: A homemade thermos filled with hot tea allows us to see the thermal energy that it radiates (by touching it with your hand) or the one that it conserves (when you drink a cup of tea). The thermos prevents heat radiation (or minimizes it greatly) and thus preserves the temperature of the fluid.
  • Baking ovens: Baking ovens act by concentrating thermal energy and increasing the temperature accordingly. The energy comes from the combustion of natural gas or by resistance, in the case of electric furnaces. The result: Food is changed (cooked) by the effect of heat.
  • Light a fire: Through a chemical reaction , the energy contained in the wood is released , and the fire itself will be our new thermal source.

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