A novel approach to storing renewable energy has been put forth

In the quest for conserving energy, researchers are leaving no stone unturned. As far as recent efforts go, the most highly-publicized development has been the Tesla-created giant battery — the Hornsdale Power Reserve (HPR) in South Australia — which recently reported savings of $40 million in its first year. However, the Neoen-owned HPR is still just a giant lithium-ion battery, and lithium is not in unlimited supply.

Fortunately, researchers at MIT have come up with a concept for what is being referred to as the “sun in a box.” Officially given the far less catchy name, of the Thermal Energy Grid Storage-Multi-Junction Photovoltaics (TEGS-MPV), the concept involves harvesting energy from heated silicon.

Sun in a Box

The Sun in a Box would consist of two storage tanks, one with comparatively cool silicon, kept at 1,920° Celsius (3,500° Fahrenheit), and the other with molten silicon kept at 2,370° Celsius (4,300° Fahrenheit). The silicon is kept at those temperatures using excess renewable energy from solar panels or wind farms.

When more energy is needed, the white-hot molten silicon is pumped through special tubes, causing them to emit light. The light is then picked up by multijunction photovoltaics — a type of solar cells — and converted into energy. As light is emitted, the silicon is cooled and ready to be passed back into the cooler storage tank, where it waits until more energy is needed and it is heated again to restart the process.

The Storage Units

Of course, the 33-foot wide tanks need to be incredibly insulated to store silicon at such high temperatures. As such, they are made of graphite, some of which reacts with the silicon to form silicon carbide, creating a thin protective layer ion the inside of the tank that keeps it lukewarm to the touch outside.

According to a statement issued by MIT, the researchers believe that each unit could be able to power a community of 100,000 homes solely on renewable energy. Asegun Henry of the MIT Department of Mechanical Engineering explains that the sun in a box units are “geographically unlimited” and offer a more affordable version of renewable energy than hydroelectric which is currently the most inexpensive form of clean energy.

In discussing the potential for the TEGS-MPV, Henry posits, “We’re developing a new technology that, if successful, would solve this most important and critical problem in energy and climate change, namely, the storage problem.”