Coupling the digital twin technology and life cycle assessment: Carbon dioxide emissions from polysilicon production

Abstract

With global warming becoming more serious, countries have begun to strengthen the regulation of carbon dioxide (CO₂) emissions, especially in high‑carbon industries such as metallurgy. This paper uses Plant Simulation v14.0 (PS) software to carry out digital twin (DT) modeling of a polysilicon factory in China. In order to study the carbon emissions in the polysilicon production process, and then integrates the calculation logic of life cycle assessment (LCA) into DT technology (DT-LCA) in order to carry out LCA of the modeled factory. As a comparison, eBalance v4.7 (eB) is applied to implement regular LCA of the modeled factory and thorough analysis of CO₂ emission during the production process. As is shown in the contributions analysis, trichlorosilane (TCS) reduction, metallurgical silicon smelting and TCS rectification account for three primary resources for the production of CO₂, with the exact percentage being 59.09 %, 11.50 % and 8.21 % respectively. The sensitivity analysis shows that the consumption sensitivity of electricity and TCS (added) rank at the top in the process of TCS reduction, with the exact numbers being 39.84 % and 18.87 % respectively. Next, the electricity consumption in the metallurgical silicon smelting process and the steam consumption in the TCS rectification process are respectively 7.72 % and 6.47 %. By LCA calculation, the production of 1 kg polysilicon results in up to 113.30 kg CO₂, while, if DT-LCA calculation is applied, 108.93 kg CO₂ is made in the same process. With a 96.14 % of matching between the two results, it has been proved that online monitoring of the total CO₂ emission during the production of polysilicon, which comprises both direct and indirect emissions, can be realized using DT-LCA emissions. This will facilitate the digitization and intelligentization of the domestic silicon industrial chain and provide data support for the establishment of carbon emission benchmark in high‑carbon industries (e.g., polysilicon industry) and promote the expansion of carbon trading market in China. Finally, based on the analysis results, suggestions for further reduction of CO₂ emission were given.