Molten silicon energy storage system created

A team of Spanish researchers are developing a system which allows energy to be stored in molten silicon.

The scientists, from Universidad Politécnica de Madrid, aim to store renewable energy surplus as heat in silicon up to temperatures of 1400°C. The element is the most abundant in the Earth’s crust and it is hoped this system could introduce a new generation of low cost power stations.

Alejandro Datas, a researcher involved in this project, said: “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. The use of thermophotovoltaic cells is key in this system, since any other type of generator would hardly work at extreme temperatures.”

Energy storage using molten salts is nothing new - solar powered systems where molten salts are used to store energy already exist. Electricity can then be provided using a thermal generator when needed.  However, silicon is able to store more than 1Mwh of energy in a cubic metre, ten times more than using salts. These thermophotovoltaic cells can produce 100 times more electric power per unit area than conventional solar cells and can convert sunlight into electricity more efficiently.

The scientists hope to use this system initially in the solar energy sector, as it is simpler to set up. Ideas to store energy for the housing sector and manage both electricity and heating needs for urban areas have been proposed. They have received funds through the EXPLORA project from the Spanish Ministry of Economy and Competitiveness.

This system has been published in Energy and the academics have also started a business project — SILSTORE — to industrialise the first-lab scale prototype they are currently building.