The second most abundant element on Earth, not only is silicon vital for producing microchips for the electronics industry, but it is a key component in the manufacture of solar panels, making it a critical material for the green transition.
Silicon is the second most common element on Earth1https://www.tdi-sustainability.com, constituting approximately 25 percent of the Earth’s crust,2https://www.tdi-sustainability.com and primarily occurs as silica (SiO2) or SiO2-containing minerals known as silicates. Pure silicon is a metalloid material, meaning that it exhibits properties typical of both metals and non-metals.
The leading use of silicon is as an alloy in the manufacture of ferrosilicon and aluminium-silicon, with more than half of all globally produced silicon used to produce ferrosilicon in 2022.3https://www.tdi-sustainability.com Common applications of silicon include manufacturing solar panels from polysilicon, producing semiconductors or integrated circuits on ‘chips’ made from pure silicon, and the use of silica sand and silicates in the construction industry.4https://www.tdi-sustainability.com Silicon is therefore not only a critical material in the green transition, it is also a key feedstock for producing the building blocks of all electronic circuits, which have an increasingly ubiquitous presence in our lives.
China is by far the world’s largest producer of silicon, followed by Russia and Brazil. Global silicon reserves are vast and disproportionately large in relation to demand such that quantitative estimates of silicon reserves are not available.5https://www.tdi-sustainability.com It is, however, apparent that the most severe ESG risks associated with the silicon supply chain can be found in China, with cases of human rights violations and forced labour reported.
Quartzite is mineral rich in silica, the mining of which has been reported to expose workers to several different health and safety risks, the most widespread risk is contracting a respiratory disease known as silicosis. Workers inhaling silicon dust at quartzite mines can develop silicosis, particularly if mine workers are not equipped with protective face masks.6https://www.tdi-sustainability.com The extraction of silicon from sand can also have negative consequences on aquatic landscapes and wildlife by altering the course of rivers and degrading habitats, such has been reported of happening in India or Vietnam.
Main Uses and Attributes
In its purest form, silicon is a dark, non-toxic solid, however it does not occur in its elemental form in nature. It can be found in many rocks and soils bonded with oxygen in the form of silica, or as silicon metal in a wide range of minerals. Silica most commonly occurs in the crystalline form of quartz or quartzite, of which large quantities are present in sand. Quartz and quartzite extraction is most commonly carried out by open pit mining, also referred to as sand mining, and which in some cases involves dredging river or ocean beds.7https://www.tdi-sustainability.com
Silicon and silica are highly versatile materials that have a large variety of applications in industries such as cosmetics, construction, electronics, and steelmaking. It is a key semiconducting material in the manufacture of integrated circuits and printed circuit boards, thanks to its highly regular molecular structure and wide availability.8https://www.tdi-sustainability.com This means that silicon is a vital material in the electronics industry. However, the electronics industry only accounts for approximately 10 percent of the end uses of the various forms of silicon.9https://www.tdi-sustainability.com The most common use of silicon is as slag in metallurgical furnaces manufacturing iron and steel, which requires that silica be chemically reduced to high purity silicon.10https://www.tdi-sustainability.com,11https://www.tdi-sustainability.com
Silicon is also a key material in the production of solar cells for photovoltaic renewable energy, with polycrystalline silicon, commonly referred to as polysilicon, being increasingly preferred over monocrystalline silicon as the former is less expensive to manufacture.12https://www.tdi-sustainability.com
Silica and aluminium silicate are used to make cement and concrete, which are some of the most widely used materials in the world, particularly in construction. Silica sands are also the principal ingredient of glass, which is also a ubiquitous material, whereas silicates are used in pottery, heat-resistant ceramics, enamels and in producing certain cosmetics.13https://www.tdi-sustainability.com
Beyond silicon and silica, there are also silicon-based polymers known as silicones that occur as liquids or flexible plastics that are made from an inorganic combination of silicon and oxygen. Silicones are used as sealants, adhesives, thermal and electrical insulation, and various medical uses such as implants.14https://www.tdi-sustainability.com
Supply Chain Risk
TDi assesses Silicon/Silica for key risks affecting the security of supply, and for its association with artisanal and small-scale mining.
Country Governance Risks
Silicon/Silica's association with countries experiencing:
Association with ESG issues
TDi Sustainability's data rates Silicon/Silica's association with the following issues as high or very high: