A new system based on molten silicon could store solar power ten times more efficiently than existing systems

Molten silicon offers tenfold improvement to solar energy storage

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Spanish researchers have developed a system based on molten silicon that can store solar energy ten times more efficiently than existing storage systems.

According to the team from the Solar Energy Institute of the Universidad Politécnica de Madrid (UPM), up to 1MWh of energy can be stored in just one cubic metre of molten silicon. Combined with the fact that silicon is the most abundant element in the Earth’s crust, the technology holds a promise for solving the problem of intermittency of renewable power generation.

The system, described in an article in the Energy journal, stores energy from solar rays at very high temperatures of up to 1400°C. The energy can be recovered when needed through a thermal generator.

“At such high temperatures, silicon intensely shines in the same way that the sun does; thus photovoltaic cells, thermophotovoltaic cells in this case, can be used to convert this incandescent radiation into electricity,” explained Alejandro Datas, who led the research. “The use of thermophotovoltaic cells is key in this system, since any other type of generator would hardly work at extreme temperatures.”

With conversion efficiency of up to 50 per cent, these thermophotovoltaic cells can produce 100 times more electric power per unit area than conventional solar cells.

The technology is quite similar to the existing concepts of storing solar power in molten salts. However, the salts are not only ten times less efficient, they are also more expensive and harder to obtain.

The team is currently awaiting a US patent and has started building a laboratory scale prototype that would pave the way for a commercial product.

In addition to thermal solar power plants, the researchers envisage that the system could be used in the housing sector to provide electricity and heating to residential and office buildings.


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