Despite all the potential of solar energy, it also has its disadvantages. For example, one of them is the high cost and low efficiency of long-term storage of energy. The industry has long been engaged in finding a solution to this issue, and I think on the horizon there is a very interesting idea. Swedish scientists have developed a special liquid called solar thermal fuel. Its peculiarity lies in the ability to store collected solar energy for nearly two decades.
About this work is written for four scientific articles. The last of them published in the journal Energy & Environmental Science.
“Heliotropio — it’s like a rechargeable battery but instead of electricity, this “battery” recharged by sunlight, providing you with the necessary warmth,” explains Jeffrey Grossman, an engineer from mit working with this material.
The basis of heliotopos developed by scientists from Chalmers Institute of technology (Sweden), are special molecules made up of carbon, hydrogen and nitrogen. When exposed to these molecules by sunlight reaction occurs: rebuild of their atomic linkages, and the output is the isomer. A strong chemical bond between the isomers captured solar energy and capable of storing even when the temperature of the molecules decreases to room (about 21 degrees Celsius). When you need access to the stored energy, the liquid is passed through the catalyst, which returns the molecules to their original shape. In this process, the output energy in the form of heat.
“The energy in the isomer can be stored for up to 18 years. If necessary, we can obtain it in the form of heat, and in such volumes, which could not even dream of,” says one of the creators of heliotopos, a specialist in nanomaterials Kasper moth-Poulsen from Chalmers Institute of technology.
A prototype power system installed on the roof of the Institute, has allowed scientists to test the liquid. According to the researchers, the results of this test attracted the attention of many investors.
A device for collecting renewable energy looks like a concave reflector with a tube in center, which runs the liquid. The design is reminiscent of radioframe, which monitors the movement of the Sun. Fluid is transmitted through a transparent tube in the center refletor and heated by sunlight, causing the molecules norbornadiene in the composition of the liquid are transformed into thermal insulation isomer, quadricyclane. The liquid is then simply placed in storage in any tank at ambient temperature with minimal loss of energy.
When the need arises to use this energy, the liquid is passed through a special catalyst, which returns the molecules to their original form, which leads to the heating of a liquid to 63 degrees Celsius.
Professor Kasper moth-Poulsen holding a tube with the catalyst in front of the vacuum setup used to measure the gradient of heat storage systems solar thermal energy
The idea is that this heat can then be used, for example, in heating systems, water heaters, dishwashers, clothes dryers and other devices, then just return it back on top for a boost.
During the tests, the researchers conceded the liquid through 125 cycles, first heating it and then cooling to normal temperature. No significant damage, for contained within it molecules were observed.
“We have made significant progress recently, having received the output of the energy system without emissions, able to work all year round,” says the moth — Poulsen.
According to the developers, through a series of refinements they managed to achieve that their liquid is now able to store the equivalent of 250 WH/kg, efficiency is almost two times more than the capacity of the batteries Tesla Powerwall.
To stop the inventors do not intend to. According to them, technology can be improved so that it could produce even more heat – at least 110 degrees Celsius.
“There is still a lot of work. We just showed that the system really works. Now we need to look further into each of its aspects, including optimizing the design,” adds moth — Poulsen.
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