They explain that it is like a rechargeable battery, but instead of electricity, you put sunlight in and get heat out, triggered on demand. The fluid is actually a molecule in liquid form composed of carbon, hydrogen and nitrogen, and when it is hit by sunlight, it does something unusual: the bonds between its atoms are rearranged and it turns into an isomer.
Energy from the Sun stays there even when the molecule cools down to room temperature. When the energy is needed the fluid is simply drawn through a catalyst that 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.
The renewable, emissions-free energy device is made up of a concave reflector with a pipe in the centre, which tracks the Sun like a sort-of satellite dish. The system works in a circular manner. Pumping through transparent tubes, the fluid is heated up by the sunlight, turning the molecule norbornadiene into its heat-trapping isomer, quadricyclane. The fluid is then stored at room temperature with minimal energy loss.
When the energy is needed, the fluid is filtered through a special catalyst that converts the molecules back to their original form, warming the liquid by 63 degrees Celsius (113 degrees Fahrenheit). The researchers claim their fluid can now hold 250 watt-hours of energy per kilogram, which is double the energy capacity of Tesla's Powerwall batteries. They think they can get even more heat out of this system, at least 110 degrees Celsius (230 degrees Fahrenheit) more.
The hope is that this warmth can be used for domestic heating systems, powering a building's water heater, dishwasher, clothes dryer and much more, before heading back to the roof once again. The technology could be available for commercial use within 10 years.
CARLY CASSELLA 6 NOV 2018
Image credit: Chalmers University of Technology