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Environmental life cycle assessment of the Elkem Solar Metallurgical process route to solar grade silicon with focus on energy consumption and greenhouse gas emissions
Glockner, R.; Odden, J-O.; Halvorsen, G.; Tronstad, R.; Wild - Scholten, M.J. de
Gepubliceerd door: Publicatie datum:
ECN Zonne-energie 17-10-2008
ECN publicatienummer: Publicatie type:
ECN-M--08-069 Conferentiebijdrage
Aantal pagina's: Volledige tekst:
8 Download PDF  (96kB)

Gepresenteerd op: Silicon for the Chemical and Solar Industry IX, Oslo, Norway, 23-26 juni 2008.

Today more than 95% of solar grade silicon feedstock is produced by decomposition of (chloro)silanes using Siemens, Komatsu or FBR (Fluidised Bed Reactor) – technology. Metallurgical refined silicon of solar grade quality will in the coming years become increasingly available to the solar market and may reach a market share of 20-30% within 2011. Energy consumption and life cycle CO2 - emission are important competitive factors. The industry will be faced with complete life cycle assessment (LCA) studies to compare solar energy with other sustainable energy sources. The present paper reports on an environmental LCA study performed on Elkem Solar Silicon (ESS™) as the single source of solar grade silicon (SoG-Si) used in the production of a rooftop multicrystalline photovoltaic system. Life cycle green house gas (GHG) emissions and cumulative energy demand (CED) are estimated for feedstock plants located in Norway. A sensitivity analysis is done using Norwegian and European electricity mixes. Energy pay-back times (EPBT) are calculated for PV-systems mounted in Southern and North Western Europe. The results show that the EPBT applying ESS produced in Norway is 1.1 and 1.9 years for a system installed in Southern and North Western Europe, respectively. Life cycle emissions of GHG are estimated to be ~14 g CO2-eq / kg ESS produced. The total life cycle GHG emissions for a rooftop PV system installed in Southern Europe is estimated to be approximately 23 g CO2-eq / kWh. For both EPBT and GHG emissions, the contribution from production of ESS is comparable in size to contributions from production of wafer, cell, laminate and inverter and more than 3 times lower than for conventional gas route processes.

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