The process of making silicon
Despite the fact that silicon is the second most abundant element in the earth’s crust, it is not found naturally in a pure form. It occurs most commonly in the form of quartz (SiO2), which is about 50% silicon by mass. Quartz is found in many parts of the world, and is obtained from surface mines. However, quartz is not found in quantity in Iceland, and the quartz used by the plant will come from Spain, France and Egypt.
The silicon is manufactured by quartz electrolysis, which will be carried out eventually in four electric arc furnaces at a temperature of around 1900°C. The furnaces can be described as large, sealed, water-cooled tanks with brick linings. Three electrodes protrude from the roof of the furnaces which are used to electrolyse the silicon.
The plant’s production process inevitably emits carbon dioxide, which contributes to global warming. However, CO2 emissions will be much lower at Stakksberg than in 90% of other silicon plants in the world. In Stakksberg’s plant all the energy comes from renewable energy sources, with the result that Stakksberg’s CO2 emissions will be substantially lower than the average for silicon manufacturers elsewhere.
In addition, Stakksberg uses a feasible ratio of wood charcoal wood chips which come from renewable and carbon-neutral forests, which will not contribute to global warming as the CO2 is re-absorbed by new trees.