Assessment of the overall resource consumption of germanium wafer production for high concentration photovoltaics
The overall resource requirements for the production of germanium wafers for III–V multi-junction solar cells applied in concentrator photovoltaics have been assessed based on up to date process information. By employing the cumulative energy demand (CED) method and the cumulative exergy extraction from the natural environment (CEENE) method the following resources have been included in the assessment: fossil resources, nuclear resources, renewable resources, land resources, atmospheric resources, metal resources, mineral resources and water resources. The CED has been determined as 216 MJ and the CEENE has been determined as 258 MJex. In addition partial energy and exergy payback times have been calculated for the base case, which entails the installation of the high concentration photovoltaics (HCPVs) in the Southwestern USA, resulting in payback times of around 4 days for the germanium wafer production. Due to applying concentration technology the germanium wafer accounts for only 3% of the overall resource consumption of an HCPV system. A scenario analysis on the electricity input to the wafer production and on the country of installation of the HCPV has been performed, showing the importance of these factors on the cumulative resource consumption of the wafer production and the partial payback times.
• The Ge-wafer production for concentrator solar cells was inventoried and assessed.
• The cumulative energy demand was determined as 216 MJ wafer−1.
• The cumulative exergy extraction from the natural environment was 258 MJex wafer−1.
• System installation in the SW USA results in Ge-wafer payback times of ca. 4 days.
• The Ge-wafer represents only 3% of the concentrator PV system resource requirements.
Fig. 1. Overview of germanium wafer production.
Source: Resources, Conservation and Recycling