What Is Thermal Energy?

With the world moving towards renewable energy sources, you may often get confused with thermal energy and why it is so much important to learn about it. As it is something that you come in contact with every day in one form or another, the thought blows up in your mind, and you put effort into finding the right answer to what is thermal energy.

Even if you have no science background and have forgotten what you have been taught during your school days, this article is going to help you relearn the concept in the simplest manner possible. Discussing the use of it, we will also see how important it is for us to learn about thermal energy. So, let’s jump into the world of thermal energy and understand what it is.

Thermal energy

Thermal energy is the energy possessed by an object included within a system due to the movement of atoms and is responsible for its temperature, according to a definition.

In other words, you can simply say that energy produced by the movement of particles within a substance is known as thermal energy. First discovered by James Prescott Joule in 1847, it is because of him the energy is measured in units called “Joule,” also represented as “J”.

The concept of thermal energy is not complete without studying thermodynamics. Thermal energy is also said to be heat energy as heat is the flow of thermal energy but, this is not exactly the case. To get a clear picture of what is thermal energy, let’s also go through thermodynamics.

What are thermodynamics?

Conservation of energy or the study of energy transformation, the correlation, and the bond between heat and thermal energy is what is known as the principle of thermodynamics. Thermodynamics plays a major role and is referred to as the branch of physics studying about work, heat, temperature, and energy.

Dealing with how heat works and what is the relationship of it with thermal energy, thermodynamics presents you with the four laws as stated below.

  • The zeroth law says that if two systems having the same heat flow come in contact with a third system, all three systems will have an equal share.
  • The first law affirms that energy is neither produced nor can be destroyed. It’s only a transformation from one condition to the other. It’s also known as the energy conservation law.
  • The second law of it presents to you that no closed system will ever stay the same. A different perspective can be derived from this law. However, to understand it clearly, you can take an example that hot things will cool down until and unless you do something to stop it. Heat goes along from hot to cold objects automatically.
  • The third law tells you that when temperatures reach absolute zero, the entropy of a thermal energy system will approach a constant minimum value.

While you don’t have to go into the details of these laws at this stage, it is important to have a brief understanding of each in order to grasp what is thermal energy.

The importance of thermal energy

Thermal energy is an important aspect of our life. The fact that we can use it for a variety of purposes is to get maximum benefit. Among all, thermal energy offers the world a new renewable energy source through which we can power the entire world. It can be stored in thermal power plants and can be reused afterward.

The ability to store energy is the biggest factor that makes thermal energy useful and valuable. Other than using it for power, thermal energy is used differently in diverse contexts for various applications.


No more regret of missing the science class in school. By reading this article, you have equipped yourself with all the information you need to answer what is thermal energy. If it feels right and you want to know more about it, check out if thermal energy is potential or kinetic.

Thermal energy flows as heat, and if you are still confused a bit, why not go through the examples of thermal energy, and clear your concepts once and for all. Also, do not forget to share and save others from regrets of not knowing about the importance of thermal energy and what it is.