A group of MIT, Georgia Institute of Technology and National Renewable Energy Laboratory researchers say their molten silicon energy storage design concept could help power cities – and be much cheaper than pumped hydro.
The Thermal Energy Grid Storage-Multi-Junction Photovoltaics (TEGS-MPV) system envisions the use of electricity sourced from renewables such as wind or solar power to heat silicon to extremely high temperatures.
The silicon would be stored in two 10-metre wide tanks made from graphite – a material that could withstand the temperatures required to run the system. One tank would be a “cold” tank containing silicon heated to almost 3,500 degrees Fahrenheit (~1,900 Celsius). This tank would be connected to a “hot” tank via tubes exposed to heating elements, raising the temperature to around 4,300F (~2,370 Celsius).
When electricity is needed, the silicon is pumped through an array of tubes that emit light. This light is then converted to electricity via specialised solar cells1. The somewhat cooled silicon would then be pumped back into the “cold” tank, ready to repeat the cycle.
As you can imagine, the pump required to perform this work would have to be incredibly robust. It seems that challenge has been sorted, with the MIT team having already developed such a device that has the highest heat tolerance on record.
The researchers estimate the TEGS-MPV system would cost about half as much as pumped hydro storage and a single system could enable a small city of around 100,000 households to be powered entirely by renewable energy.
In-depth details of the team’s research have been published in the journal Energy and Environmental Science.
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