the main problem of solar energy is that there is not an efficient and economic way, to date, to store it for use at a later time. In recent years, studies have focused precisely on finding a solution to this obstacle: a Swedish study, for example, has developed a special fluid that manages to store energy from the sun up to 18 years. A simple and low-cost system that could start a second era of renewable energy.
"A solar thermal fuel is like a battery, only that, instead of electricity, solar energy is poured into heat," explained the scientists who took part in the study.
It is a liquid formed by Norbornadiene, a molecule composed of carbon, nitrogen and hydrogen; when it is hit by the sun's rays, this compound does something very unusual. The bonds between the atoms are rearranged in a conformation to a higher energy level. The energy of the sun's rays is therefore trapped in the strong bonds of the molecule, and remains so even when the liquid is brought to room temperature.
When the stored energy is to be used, the liquid is passed through a catalyst, which suggests the molecule return to its initial stage, the one with the lowest energy.
The energy that differentiates the two states is released in the form of heat - about 63 ° C - that could be used for the heating system of a house, to provide hot water, to power the dishwasher, the hair dryer or the dryer, for example.
The liquid can be part of a circuit, since it is renewable: just let it enter again in contact with the sun rays and then, eventually, through the catalyst: the researchers have already tested the cycle 125 times with excellent results.
The improvements that can be made to the liquid are numerous: for example, we are experimenting with a way to bring to 110 ° C the temperature of the heat released by liquid. If everything proceeds without too many obstacles, the researchers say, the technology will be available on the market within 10 years.