This problem has been tormenting solar energy for some time now, but this can change because it offers an extremely intriguing way of saving solar energy.
Swedish scientists have created a special liquid called "solar fuel". It is said that this fuel can store accumulated solar energy for more than a decade.
"Solar fuels are like a battery, but instead of electricity, you put in solar rays and heat. Everything depends on your needs," said Jeffrey Grossman, MIT engineer with these materials, NBC News.
This fluid is actually a special liquid molecule, to which researchers from the Chalmers University of Technology (Sweden) have been working for over a year.
This molecule consists of carbon, hydrogen and nitrogen, and when exposed to sunlight, it begins to behave abnormally: connections between atoms are reset and the molecule becomes an isomer.
Like plundering traps, solar energy is captured in isomers that have strong chemical connections. And the energy remains closed, even when the molecule cools down to room temperature.
When it comes to energy – say, at night or in winter – the liquid is exposed to a catalyst that restores the molecule to its original state and thus relaxes the energy.
"Energy in these isomers can be stored up to 18 years," says one team member, a nanoscale scientist at the Chalmers University, Kasper Moth-Poulsen. "When we decided to release the blocked energy, we got a temperature rise that was higher than we expected."
Such a prototype of the energy system was installed on the roof of the university building, and when the new liquid was used and highly optimistic results were obtained, the scientists attracted many investors.
Renewable and non-polluting, the new energy device consists of a concave reflector with a centered tube that catches the sun's rays and acts as a kind of satellite dish.
MOST system works on the principle of closed circulation. The permissible liquid through the transparent tubes is heated by the sun, and the so-called norbornadiene molecules in the liquid are converted into isomeric heat blocking quadripettes. This liquid is then stored at room temperature to minimize energy loss.
When energy is needed, the fluid passes through a special catalyst, which restores the molecules to the original form, and this fluid rises to 63 degrees Celsius. Therefore, it is believed that this heat can be used in various building heating systems.
Scientists have repeatedly used the fluid 125 times – they collected the heat of the sun, protected it and softened it – and did not notice that it would cause more damage to these molecules.
"We have recently made many important discoveries, and today we have an energy system that works all year round and does not pollute the environment," said Moth-Poulsen.
According to NBC, scientists made some discoveries that enabled special liquids to store 250 watts per kilogram, which is twice as efficient as the Powerwall Tesla battery system offers.
But there are still many opportunities for new achievements. Scientists are convinced that with the right manipulation tools they can get even more heat from such a system – at least 110 degrees Celsius.
"There is still a lot to do, we only succeeded in making this system work, now we must ensure that everything is optimally designed," says Moth-Poulsen.
If everything goes as planned, Moth-Poulsen believes that this technology can be commercially commercialized in the next 10 years.
The latest research results have been published in the journal Energy & Environmental Science.