Dynatec reactor for refining silicon

Challenge

Producing solar panels requires the purification of silicon, which is a slow and energy intensive process. Currently production of solar grade silicon is primarily carried out using the Siemens reactor. Silicon rods are heated to between 800 and 1,100 degrees Celsius, and a silicon containing gas is injected and thermally decomposed releasing silicon that is deposited onto the rods. To prevent silicon growth on the walls, these are kept at below 200 degrees Celsius.

Innovation

Dynatec has produced a centrifugal reactor which lowers the energy intensity of refining silicon in solar panel production by 90% compared to the decomposition reactors currently in use.

Instead of keeping hot elements inside a cool chamber, with Dynatec’s reactor the deposition takes place on the walls. The whole reactor is also set into rotation and built as a centrifuge. By inverting the process, it is possible to grow the silicon without maintaining large temperature differences.

Action

With support from the Research Council of Norway, Dynatec has built two demonstration reactors. The energy consumption of a decomposition reactor is currently about 70 kwh/kg, while the new centrifugal reactor has demonstrated production of first grade silicon at less than 5kwh/kg.

Potential

Having already built two successful demonstration reactors the company is now building a full-scale industrial reactor in cooperation with a customer.

Dynatec has also founded two spin off companies where the centrifugal reactor is to be used differently and refitted to make silicon nano-particles of similar shape and size for both battery and medical applications.

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