Thermal Energy Storage

Thermal Energy

When we talk about thermal energy, we refer to the heat energy that is produced when there is a rise in temperature. This rise in temperature causes the atoms and molecules in a material to vibrate at a high frequency. It will eventually collide with each other. As a result, energy is dissipated from them, which is called thermal energy. Now that we know what is thermal energy let's take a look at the thermal energy definition.

Thermal energy is defined as when any atoms or molecules of an element start vibrating due to the rise in temperature; it produces energy which is called thermal energy. In other words, thermal energy definition can be the movement of atoms and molecules. These atoms and molecules will keep moving faster as the temperature rises. Therefore, we can say that the kinetic energy of the particles and their thermal energy is the same. Now that you are familiar with what is thermal energy and the thermal energy definition, we will see the different sources of thermal energy.

Sources of Thermal Energy

  • Chemical energy: We can convert chemical energy to thermal energy. Some good thermal energy examples are the burning of wood and coal.

  • Solar energy: Solar energy comes under the best sources of thermal energy. It is the cleanest and readily available source of energy.

  • Mechanical energy: We can convert mechanical energy to thermal energy. An excellent thermal energy example is the energy released due to friction.

  • Fossil fuels: Fossil fuels are burnt to produce thermal energy.

  • Geothermal energy: We can convert geothermal energy to thermal energy. A good thermal energy example is the energy released due to volcanoes, hot springs, and geysers.

Thermal Energy Storage

It is crucial to understand exactly what is thermal energy storage. Energy storages are designed to store energy, and when the demand for power increases, it can maintain a constant supply. It helps to keep the supply and demand for energy, use renewable sources of energy, and increase the efficiency of the use of energy. Thermal energy storage is a technology that stores up thermal energy. It is obtained by continuously heating and cooling the storage system. The energy stored can be utilised in the future when the need arises. By using energy storage, we can reduce the time and rate mismatch between the supply and demand for energy.

Take solar energy for an example. Solar energy can only be produced during the day when the temperature of the environment increases. But the same energy is utilised day and night. Therefore, storing energy becomes essential. By storing the thermal energy during the day, we can use it at night.

Working of Thermal Storage Energy

To properly understand the working of the thermal energy storage system, we will look at an example relating to an air-conditioning system.

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The image shows the various steps in the working of thermal energy storage.

In the first step, during night time, we take a mixture of water and 25% of propylene glycol or ethylene. This mixture is then cooled with the help of a chiller. In our example, we are using an ice storage cooling system. The next step is to circulate this mixture in the ice bank, which acts as a heat exchanger. In the tank, we can freeze 95% of the water. Then ice is uniformly created inside the container with the help of the heat exchanger.

Now, during the day time, the glycol from the mixture can freely move between the ice. This glycol is then used to deliver the stored energy into a room of a building. A fan is used to blow off the cold atmosphere into the room.

There are two main types of thermal energy storage. The first type of thermal energy storage is sensible heat storage. In this type, heat energy is stored in either liquid material or solid material. The second type of thermal energy storage is latent heat storage. In this type, heat energy is either stored in Solid-Solid material, Solid-Liquid material, or Liquid-Gas materials.

Different Types of Thermal Energy Storage

Type of Thermal Energy Storage

Functional Principle

Phases

Examples

Sensible Heat

The temperature change of the medium with the highest possible heat capacity

Liquid, Solid

Hot water, organic liquids, molten salts, and liquid metals.

Latent Heat

Essentially heat of phase change

Liquid-Solid, Solid-Solid, and Liquid-Gas

Nitrides, Chlorides, Hydroxides, Carbonates, and Fluorides.


Thermal Energy Storage Applications

Thermal energy is a good source of energy. Let’s look at some of the good uses of thermal energy.

  • We use thermal energy in solar power plants to provide energy during the night time.

  • Thermal energy is used in cooking, baking, water heating, and heating.

  • It is also used in thermal processing of non-metals.

  • It has applications in automobiles.

  • They are used as incinerators to burn down waste.

  • It has applications in thermal power plants.

FAQ (Frequently Asked Questions)

1) How is thermal energy generated?

Answer: Everything around us is made up of molecules and atoms. These molecules and atoms are always in motion; they will either move back and forth or will bump into each other. When they are in motion, they produce heat or better known as thermal energy. Thermal energy is the heat energy that is produced when there is a rise in temperature. This rise in temperature causes the atoms and molecules in a material to vibrate at a higher frequency. It will eventually collide with each other. As a result, energy is dissipated from them, which is called thermal energy. As these atoms and molecules keep moving faster, the temperature will keep rising.


2) What do we use thermal energy?

Answer: Thermal energy can be considered as a renewable source of energy depending upon the fuel used to produce it. There are a lot of applications of thermal energy in our life. We use it for cooking our food, boiling our water, etc. It is widely used in power plants to produce electricity. It also has medical applications, where it is used to sterilise pieces of equipment.