Thermal Energy Storage Innovations

 Introduction-

Have you ever wondered how and why must we store energy? It is necessary to be emphasized that none of the energy sources can be fully satisfying. It is due to: 

— Time-variable demands, 

— Time-variable supply of the so-called renewable energy sources, e.g. solar energy and wind power.

— The efficiency of energy conversion and utilization, 

— The concentration of ability to work. 

                          

Ref - https://energystorage.org/why-energy-storage/benefits/

                                 

The storage of energy in different forms plays an important role in the effective use of energy. Thermal energy storage (TES) can substantially reduce the peak power requirements. It is necessary to incorporate TES in solar energy and heat recovery systems as there is a temporal mismatch in the supply and use of this form of energy. 

Development and implementation of TES systems are also forced by Environmental concerns because they reduce energy consumption and allow the utilization of some clean sources of energy, e.g. solar. In large parts of the world, people have abundant heat from the sun during the day, but most cooking takes place later in the evening when the sun is down, using fuel — such as wood, brush or dung — that is collected with significant time and effort.

Phase Change Material (PCM)-

Early methods used to develop thermal storage is to use what is known as a phase change material (PCM), in which the heat provided melts the material and its phase transformation takes place from solid to liquid and thus, stores the energy released during the transformation. When the PCM is cooled back down below its melting point, it turns back into a solid, at which point the stored energy is released as heat. 

 

Phase change materials cycle
Ref - phase change materials images - Bing images

There are many examples of these materials, including waxes or fatty acids used for low-temperature applications, and molten salts used at high temperatures. But all current PCMs require very high insulation, and after cooling the PCM back down below its melting point, they pass through that phase change temperature uncontrollably, losing their stored heat relatively rapidly.

What’s New?

Now, a chemical composite developed by researchers at MIT could provide an alternative. It could be used to store heat from any source of heat, not just solar during the day, in a kind of thermal battery, and it could release the heat when needed, for example for cooking or heating after dark. The system uses molecular switches that change shape in response to light. These switches when integrated into the PCM, the phase-change temperature of the hybrid material can be adjusted with light, allowing the thermal energy of the phase change to be maintained even well below the melting point of the original material.

The UV-activated thermal energy storage material shows the rapid crystallization and heat discharge upon visible light (blue LED) illumination. (Grossman Group at MIT)

Ref- A new way to store thermal energy | MIT News | Massachusetts Institute of Technology

The research shows that thermal energy is hard to hold.  So, they wanted to develop a trigger system that helps them to hold the stored thermal energy and release it when required. The researchers accomplished this by combining the fatty acids with an organic compound that responds to a pulse of light. With this arrangement, the light-sensitive component alters the thermal properties of the other component, which stores and releases its energy. The hybrid material melts when heated, and after being exposed to ultraviolet light, it stays melted even when cooled back down. Next, when triggered by another pulse of light, the material re-solidifies and gives back the thermal phase-change energy. 

By integrating a light-activated molecule into the traditional picture of latent heat a kind of control knob is added for properties such as melting, solidification, and super-cooling. The researchers have installed a new energy barrier, so the stored heat cannot be released immediately.” In its chemically stored form, the energy can remain for long periods until the optical trigger is activated. 

This blue LED lamp setup is used to trigger the heat discharge from large-scale films of phase-change materials.

 Ref- A new way to store thermal energy | MIT News | Massachusetts Institute of Technology

The system could make use of any source of heat, not just solar. These systems can store about 200 joules per gram which is very good for any organic PCM also it could store the same energy for about 10 hours which is much higher than currently available technologies which dissipate the energy within minutes. 

Conclusion-

This new research in the field of thermal storage has provided us with a way to store and use heat energy in a different way that is more stable and safer. The availability of waste heat is widespread, from industrial processes to solar heat, and even the heat coming out of vehicles is usually just wasted. Harnessing some of that waste heat could provide a way of recycling it for useful applications which will help the world to take a greater step towards green energy.

BLOG CREDITS:- PRIYANSHU RAGHUWANSHI 111911031 (TY METALLURGY)

                                   VARUN MUTHIYAN 142011004 (TY METALLURGY)

                                   OJAS TUMBDE 112011069 (FY METALLURGY)

References- 

1.  A new way to store thermal energy | MIT News | Massachusetts Institute of Technology

2. https://www.researchgate.net/publication/277149571_THERMAL_ENERGY_STORAGE_PROBLEMS

3. https://www.ctc-n.org/technologies/phase-change-materials-thermal-energy-storage

4. https://energystorage.org/why-energy-storage/benefits/

5. phase change materials images - Bing images

Note: This blog is meant for educational purposes only. We do not own any Copyrights related to images and information, all the rights go to their respective owners. The sole purpose of this blog is to Educate, Inspire, and Empower and to create awareness in the viewers. The usage is non-commercial (Not for Profit) and we do not make any money from it.