Storing Renewable Energy With Molten Silicon

Reliable energy storage is indispensible for photovoltaics, and a new conceptual design from MIT could deliver energy on-demand more efficiently than batteries.

Energy storage mitigates the most obvious problem with solar power – can’t harvest energy when it’s dark (or overcast). But the most popular method for banking solar power – lithium-ion batteries – is pricey, and discharging that energy on-demand is problematic.

“Even if we wanted to run the grid on renewables right now we couldn’t, because you’d need fossil-fueled turbines to make up for the fact that the renewable supply cannot be dispatched on demand,” says Asegun Henry, the Robert N. Noyce Career Development Associate Professor at MIT.

The team needed an efficient system for storing and dispatching the excess energy from wind or solar power on-demand, and they settled on a process whereby the energy is stored in large tanks of white-hot molten silicon and converted back into electricity when needed.

The overall concept is nothing new – solar plants previously used large tanks filled with molten salt. But at higher temperatures, the salt would corrode the stainless steel tanks. Silicon, meanwhile, can withstand temperatures of over 4,000°F.

And the system even has a cute nickname.

“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,” Henry says.  “It’s basically an extremely intense light source that’s all contained in a box that traps the heat.”

Read more about the ‘sun in a box’ here: http://news.mit.edu/2018/liquid-silicon-store-renewable-energy-1206