Wonderful Engineering

Scientists Develop New Liquid That Can Store Solar Energy For More Than A Decade

Solar power is so far the only solution to move away from fossil fuel dependent power supplies. To have consistent access to solar energy is difficult because it cannot be stored for a long time. However, scientists in Sweden might have solved this problem by the development of a specialized fluid called a solar thermal fuel. Jeffrey Grossman, an engineer at MIT, explained the system saying, “A solar thermal fuel is like a rechargeable battery, but instead of electricity, you put sunlight in and get heat out, triggered on demand.” The fluid was under development for more than a year by scientists from the Chalmers University of Technology Sweden. The liquid is a molecule composed of carbon, hydrogen, and nitrogen.

When sunlight makes contact with the liquid, the bonds between its atoms rearrange and transform into an energized version of itself called an isomer. The sun’s energy is then captured between the isomer. The power it obtains from the sun is caught between the isomer’s strong chemical bonds. The power stays trapped in there even when the molecules cool down to the room temperature. To use the power, the liquid is put through a catalyst which returns the molecules to its original form and releases the energy in the form of heat.

Kasper Moth-Poulsen, Professor at the Department of Chemistry and Chemical Engineering, said, “The energy in this isomer can now be stored for up to 18 years. And when we come to extract the energy and use it, we get a warmth increase which is greater than we dared hope for.” The research lab placed the prototype of the energy system on the roof of the university, and it has already gained the attention of various investors. The system works as a loop and has a concave reflector with a pipe at its center to track the sun position.

The liquid is pumped through the transparent tubes to be absorbed by the sun. As it heats, it changes from its initial form of the molecule norbornadiene into its heat-trapping isomer, quadricyclane. The energy filled liquid is then stored at the room temperature. When demand for energy occurs, the liquid is passed through a catalyst which turns the molecules to their previous state raising the temperature by 63-degree Celsius. this fluid can then be used for household purposes such as heating systems and powering some equipment like a water heater, cloth dryer and more. After all this, the liquid is pumped back to the rooftop to repeat the cycle. Researchers have so far performed the process more than 125 times without any significant damage to the molecule. This can be a pretty neat solution for storing alternative energy in the future!