Solar Thermal Fuel – The Liquid That Stores Solar Energy

Solar Thermal Fuel

Solar power is by far the most reliable and promising form of energy that, unlike other energy forms, comes without hazards to nature. And one of the most prominent challenges we need to surpass in ensuring its reliability is the long-term storage of solar energy.

Present developments imply that someday we will be able to bottle up the energy from the sun and use it during those gloomy and cloudy days to power our homes and even factories. The ground-breaking possibility provided by solar thermal fuel technology is endless.

In 2018, scientists in Sweden came up with a fantastic concept of solar thermal fuel, the liquid that acts as an effective battery.

Solar thermal fuel technology is a very new concept and is mainly in the testing phase. However, it has numerous possibilities in fulfilling our heating requirements.

Solar thermal fuel is a chemical fuel that absorbs solar radiation and stores it within the system, just like batteries. We can use this energy after several days in the form of heat energy.

Progress so far

So far, we have only absorbed solar energy and stored it in batteries. However, scientists have now shifted to this new Solar Thermal Fuel (STF) concept to ensure that solar power is reserved more effectively.

After decades of research, experts in Sweden have finally reported significant progress. They have developed a certain liquid capable of absorbing the energy from the sun, holding it for several months (even years), and releasing it as and when necessary.

At present, solar thermal fuels are available in the form of uniform films. Hopefully, this concept can be applied in every household and factory soon, pushing fossil fuels into the grave.

This particular concept ensures the enhanced performance of solar technology by storing the energy with the help of chemical reactions. The solar energy is stored in the transparent polymer film, releasing heat as needed via a simple chemical reaction.

Today, studies and experiments have concluded that we can store this energy for up to 18 years. Furthermore, when we use this stored energy, the amount of heat we receive is much more than experts had hoped.

How does it work?

Kasper Moth-Poulsen and his research group have tested a prototype of solar thermal fuel technology. The Chalmers University of Technology in Gothenburg, Sweden, has been set up with a prototype system on the roof of the physics building.

The energy system MOST works in a circular manner – completely free of emissions, and without damaging the molecules carrying the energy. ​​ ​Illustration: Yen Strandqvist

The roof of the building is enclosed in transparent tubes filled with solar thermal fluid. First, the liquid absorbs the energy from the sun. The ultraviolet rays excite the molecules and put them in an energized state.

The sunlight readjusts the bonds between hydrogen, nitrogen, and carbon atoms in the fluid and converts the norbornadiene compound into a quadricyclane compound (the energetic one).

The energy we are looking to tap in is stored in these solid chemical bonds. The energetic compound quadricyclane retains the captured solar power even when it is cooled down to room temperature.

The fluid is passed over a cobalt-based catalyst to extract this stored energy. As the liquid molecules change their forms after the chemical reaction, they shift back into norbornadiene form. An immense amount of heat energy is released during this transformation.

The released energy then heats the fuel by raising 63 degrees Celsius (113 degrees Fahrenheit). Now, this heated liquid is efficient enough to warm our houses and living spaces.

Experts have put the fluid to test through this cycle over 125 times, absorbing the sun’s heat and releasing it over and over again. And, it has been found that there is no damage to the liquid at molecular levels.

To sum it all up, the system operates circularly to produce heat energy. First, the solar thermal liquid absorbs the energy from the sun through the solar thermal collectors, commonly known as MOST (Molecular Solar Thermal Energy Storage System), laid on the roof of the building. This energy is then stored at room temperature.

When the energy is required, during the nighttime or cloudy winters – it can be tapped through a catalytic reaction releasing the stored heat energy.

Benefits and Applications of Solar Thermal Fuel

Unlike the energy generated by burning fossil fuels and natural gases, solar thermal fuels are 100% environmentally friendly. They do not radiate any carbon dioxide or greenhouse gases into the environment.

It is highly sustainable and a long-term solution to the energy needs of humans. Solar thermal fuel is very similar to a rechargeable battery. However, instead of plugging it into the electrical grid, put it out in the sun and catch that free energy radiating all over the surrounding area.

The researchers have claimed that the solar thermal fluid can hold as much as 250-watt hours of energy per kilogram. And according to NBC reports, this figure is double the energy capacity of Tesla’s Powerwall batteries.

We can use the warmth generated from solar thermal for both domestic and industrial purposes. They can meet our daily heating requirements and power and entire building’s water heaters, clothes dryers, dishwashers, and many more. As for meeting the industrial needs, manufacturers can use this energy in bleaching, distillation, and sterilization.

Today, scientists have incorporated this technology in window films to control the temperatures indoors on hot days. The application of solar thermal fuel in window blinds has already begun through Solartes AB Company.

To conclude

Experts claim that there is plenty of room for improvement in the application and possibilities rendered by solar thermal fuel technology. With accurate manipulation, scientists project that we can get more energy out of the system, at least 110 degrees Celsius (230 degrees Fahrenheit) more than what we are getting today.

Additionally, if everything goes as planned, we can expect the technology to be available for commercial use within the next ten years.

Sun in a box, a concept that might steer the global energy needs to a new and more reliable direction!