The new design stores electrical energy in the form of heat in large tanks of molten silicon. A single power plant could allow a city of 100,000 homes to be fully powered by renewable energies. Technological mix and high temperatures for the silicon solar battery.

Researchers at the Massachusetts Institute of Technology (MIT) continue to work on new ways to store electricity that can stabilize the production of non-programmable renewable energy sources.

The latest proposal in this regard, which has come out of laboratories in the United States, tackles the objective with a completely new approach. We are talking about TEGS-MPV (Thermal Energy Grid Storage-Multi-Junction Photovoltaics), a concept of “solar battery” which combines different technological solutions such as the storage of molten salt from solar thermodynamics and “cascade” photovoltaic cells. . The system would be able to store the surplus renewable electricity, storing it as heat in silicon tanks at 2000 ° C. When you want to recover the stored energy, the silicon is transferred to another tank and heated to 400 ºC additional. At this temperature, silicon emits such intense light that it can be used by special photovoltaic panels to produce energy as if it were an artificial sun.

The idea has yet to be tested on a large scale, but researchers are convinced that their design may be cheaper than lithium-ion batteries and cost almost half the cost of pumping hydropower plants (now the form of storage cheapest grid-wide electric).

How does the MIT solar battery work?

The system would consist of a large reservoir 10 meters wide, in graphite, perfectly insulated and with liquid silicon maintained at a “cold” temperature of nearly 1900 ° C. A series of pipes, exposed to heating elements, connect this storage structure to a second so-called “hot” tank.

When the surplus electricity from the grid enters the system, it is converted into heat in the pipes connecting the two reservoirs by the Joule effect. At the same time, liquid silicon is pumped from the cold reservoir to the hot reservoir and absorbs thermal energy along the way, heating up to 2,400 ° C. When the demand for electricity from the grid becomes high again, silicon – which at These temperatures make it so hot that it gets bright – it’s driven by some kind of motor in which solar cells use their white light to generate electricity.

“One of the names that people have started to call our concept is ‘sun in a box,’ coined by my colleague Shannon Yee of Georgia Tech,” says Asegun Henry, associate professor in the Mechanical Engineering Department at MIT. “It is essentially an extremely intense light source contained in a box that traps heat.”

The team working on the project say that one of these TEGS-MPV systems could be enough to power 100,000 homes, at low cost and without geographic limits. The research results were published in the journal Energy and environmental sciences.

More information: