MIT ‘sun in a box’ uses white hot silicon for energy storage

The system relies on the transfer of molten silicon between two cylindrical graphite tanks, each about 10m wide. Silicon in the ‘cool’ tank would be stored at around 1,900°C, then pumped through a network of heated pipes into the second tank, reaching temperatures close to 2,400°C. The elements heating the pipes would be powered by excess energy from the grid, theoretically from renewable sources such as wind and solar.

To feed the stored energy back to the grid, molten silicon from the second tank – now glowing white hot - is passed through a system of pipes that emit light. This light is then captured by highly efficient multi-junction solar cells. Though commonly referred to as the ‘sun in a box’, the system’s official name is Thermal Energy Grid Storage-Multi-Junction Photovoltaics, or TEGS-MPV. The research is published in the journal Energy & Environmental Science.

“One of the affectionate names people have started calling our concept, is ‘sun in a box,’ which was coined by my colleague Shannon Yee at Georgia Tech,” said corresponding author Asegun Henry, an associate professor at MIT’s Department of Engineering. “It’s basically an extremely intense light source that’s all contained in a box that traps the heat.”