Scientists in Sweden have developed a specialized fluid, called a solar thermal fuel, that can reportedly store energy captured from the sun for over a decade. “A solar thermal fuel is like a rechargeable battery, but instead of electricity, you put sunlight in and get heat out, triggered on demand,” Jeffrey Grossman, an engineer works with these materials at MIT explained to NBC News.
The fluid has been in development for over a year by scientists from Chalmers University of Technology, Sweden. The exciting liquid is a molecule composed of carbon, hydrogen, and nitrogen.
When sunlight makes contact with the liquid the bonds between its atoms are rearranged and it transforms into an energized version of itself called an isomer. The sun’s energy is then captured between the isomers’ strong chemical bonds.
Incredibly, the energy stays trapped there even when the molecule cools down to the room temperature. To put the trapped energy to use, the liquid is put through a catalyst which returns the molecule to its original form, releasing energy in the form of heat.
“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,” says the leader of the research team, Kasper Moth-Poulsen, Professor at the Department of Chemistry and Chemical Engineering. The research lab placed a prototype of the complete energy system onto the roof of the university and it has already caught the eye of several large investors.
The system works as a loop. It has a concave reflector with a pipe at its center which tracks the sun position. The liquid is pumped through transparent tubes to beheaded by the sun.
As it heats it changes from its initial form of the molecule norbornadiene into its heat-trapping isomer, quadricyclane. The energy full liquid is then stored at room temperature.
When an energy demand occurs, the fluid is pushed through a catalyst that converts the molecules back to their original form, warming the liquid by 63degrees Celsius. This warm liquid can be used for can then have application in everything from domestic heating systems, powering a building’s water heater, dishwasher, clothes dryer and much more.
The liquid is then pumped back to the roof to be rescued. So far the researchers have put the fluid through this cycle more than 125 times without significant damage to the molecule. The most recent study in the series has been published in Energy & Environmental Science.