In Liu Cixin’s short story “The Chinese Sun”, an interesting assumption is made about the utilization of solar energy. In fact, human beings have long known that the star that makes the earth a livable planet contains huge energy.
This nearly perfect sphere gives us light, heat and energy, and breeds life on the earth. After tasting the sweet and bitter fruit of fossil fuels, human beings have made greater efforts to develop clean energy. However, the energy emitted by the “treasure house” of the sun is difficult to store.
In 2017, a research team from Chalmers University of Technology in Sweden developed a system that can store solar energy, called MOST system (Molecular Solar Thermal Energy Storage System). After that, they cooperated with researchers from several universities such as Shanghai Jiaotong University to explain in detail how this system can be combined with compact thermoelectric generators to convert solar energy into electricity. Relevant research articles written by Wang Zhihang, Wu Zhenhua and Hu Zhiyu have been published in the journal Cell Reports Physical Science.
Molecular solar energy storage system is a specially designed closed energy system consisting of carbon, hydrogen and nitrogen molecules. When exposed to sunlight, their shape will become an energy-rich isomer: a molecule composed of the same atoms, but arranged together in different ways.
In this way, isomers can be stored in liquid form for future use, such as at night or in winter when the sun cannot shine. This system that can store solar energy as chemical energy has been improved by researchers to store energy for up to 18 years.
To use the stored energy, a specially designed catalyst is required to release the saved energy in the form of heat and restore the molecule to its original shape. In this way, it can be reused in the heating system. In combination with the micro-sized thermoelectric generator, it can use solar energy when solar radiation is not received.
The research team also carried out relevant experiments: researchers in Sweden sent their specially designed molecules loaded with solar energy to colleagues at Shanghai Jiaotong University. There, the energy is released and converted into electricity using the generator they developed there.
That is to say, Swedish sunshine is converted into electricity in China.
It can be seen that using this liquid system to store solar energy is not only feasible, but also has broad prospects. Wang Zhihang, one of the researchers, said that the generator is an ultra-thin chip that can integrate the system into electronic products such as smart watches and headphones.
One of the main problems of solar energy is storage. Solar cells can be used as a short-term solution, but not for long-term storage or power supply for the whole city. Here are some techniques for storing sunlight.
1. Taineng stored in oil well
Hyperlight Energy, headquartered in California, will conduct pilot installation. They plan to use the existing oil wells as solar hot wells and convert the stored energy back to clean electricity when needed.
Scientists have learned how to make solar energy work at night
2. Store solar energy in the air and water during the day and take it out at night
Scientists have learned how to make solar energy work at night
In a small community called Kibbutz Yahel, not far from the Red Sea, residents have begun to use a new technology that can store solar energy cheaply and generate electricity at night. The operation principle is as follows: In the daytime, the excess energy generated by solar panels drives a system in which water is used to condense the air in the underground water tank. After sunset, the air is released to power the turbine and generate electricity. Other collective farms are waiting and observing whether this plan is effective. If it is easy to use, then follow it.
3. Store solar energy in sulfur
Scientists have learned how to make solar energy work at night
Through the Pegasus project, DLR is studying a new type of concentrated solar thermal power generation technology to store solar energy in sulfur. This technology operates as a self-contained cycle, but its practical advantages lie elsewhere: it can not only generate electricity without any greenhouse gas emissions, but also help the chemical industry and agricultural decarbonization.
4. Use thermal cells to store solar energy
Scientists have learned how to make solar energy work at night
A team from the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory has developed a thermal cell that can emit light like tungsten filament and effectively store wind and solar energy. This technology has achieved a jump of nearly 30% in the efficiency of thermal photovoltaic (TPV). This semiconductor structure can convert photons from heat sources into electricity, just as solar cells convert sunlight into electricity.
