silicon production, single crystal, Czochralski process, photovoltaics, UPR, ecoinvent 3.6, Undefined

Categories:
ISIC4 categories:
C:Manufacturing/20:Manufacture of chemicals and chemical products/201:Manufacture of basic chemicals, fertilizers and nitrogen compounds, plastics and synthetic rubber in primary forms/2011:Manufacture of basic chemicals
Location:
RER - Europe
Reference year: 1992 - 2006
Description

Location: RER - Europe
This dataset represents the production of a monocrystalline silicon block, for use in photovoltaics, using the Czochralski process. The inventory data is based on literature information and environmental reports of one producer in Germany.
References:
Jungbluth N., Stucki M, and Frischknecht R. (2009) Photovoltaics. In Dones, R. (Ed.) et al., Sachbilanzen von Energiesystemen: Grundlagen für den ökologischen Vergleich von Energiesystemen und den Einbezug von Energiesystemen in Ökobilanzen für die Schweiz. ecoinvent report No. 6-XII, Swiss Centre for Life Cycle Inventories, Dübendorf, CH, 2009.
Undefined unit processes (UPRs) are the unlinked, multi-product activity datasets that form the basis for all of the system models available in the ecoinvent database. This is the way the datasets are obtained and entered into the database by the data providers. These activity datasets are useful for investigating the environmental impacts of a specific activity (gate-to-gate), without regard to its upstream or downstream impacts.

Technology

This dataset models the Czochralski process for the production of monocrystalline silicon blocks.
The following description of the production process is based on an older literature reference (Hagedorn & Hellriegel 1992) and has not been updated for this dataset.
The purified silicon and recycled silicon parts are broken down to a size of 0.1 to 7.5 cm. In an acid bath with nitric acid, hydrogen fluoride and acetic acid the surface is purified and SiO2 is removed. The following reactions take place:
3 Si + 4 HNO3 -> 3 SiO2 + 4 NO + 2 H2O
SiO2 + 6HF -> H2SiF6 + 2 H2O
The waste gases of the process (e.g. NOx, HF, acetic acid- and nitric acid) are treated in a gas cleaner before they are released. Information about possible releases is not available. Effluents are discharged directly and have been assessed with older literature data. Deionised water is used for cleaning and acetone is used for final drying. The cleaned silicon parts are melted in a crucible and a seed crystal is first dipped into the melt. Then the seed is slowly withdrawn vertically to the melt surface whereby the liquid crystallises at the seed. The pulling is done under argon inert gas stream. In order to reduce the argon consumption, a pressure of 5 to 50 mbar is required.
Reference:
Jungbluth N., Stucki M, and Frischknecht R. (2009) Photovoltaics. In Dones, R. (Ed.) et al., Sachbilanzen von Energiesystemen: Grundlagen für den ökologischen Vergleich von Energiesystemen und den Einbezug von Energiesystemen in Ökobilanzen für die Schweiz. ecoinvent report No. 6-XII, Swiss Centre for Life Cycle Inventories, Dübendorf, CH, 2009.
G. Hagedorn, „Kumulierter Energieaufwand von Photovoltaik- and Windkraftanlagen“, IfE-Schriftenreihe, Heft Nr. 25, 1. Auflage, TU München, Technischer Verlag Resch KG, 1992

Process type
Unit
Supported nomenclature
ecoinvent 3.6
LCI modeling approach
Before modeling
Multifunctional modeling
NONE
Format
ECOSPOLD2
Aggregation type
NOT_APPLICABLE
Data provider
ecoinvent
Review status
External
Cost
For sale
License

ecoinvent EULA

Contact
support@ecoinvent.org