The ability to collect heat from the sun as it hits glass windows during the day, and release it at night when it gets cold, sounds a brilliant idea to combat global heating. It would be still better if heat could be stored until the following winter and used to warm homes and offices.
A team of scientists has designed a molecule than can do both those things. It is made of carbon, hydrogen and nitrogen and when hit by sunlight re-forms into a different molecule that stores the energy to be released later.
A film on the glass of office blocks would be tinged yellow in the mornings until the window is in the sun, when the molecule would capture the heat and become entirely transparent. It goes on working, removing the heat until the sun goes down, when the molecule gradually releases the heat and resumes its yellow colour. In homes the system can be adapted to liquid form and the transformed molecules collected in a tank in the summer then, in the winter, mixed with a catalyst to release the stored heat back into the house.
It sounds too good to be true but Swedish researchers say they are close to commercial applications, potentially saving costs in air conditioning and heating.