Environmental impacts of copper‑indium‑gallium-selenide (CIGS) photovoltaics and the elimination of cadmium through atomic layer deposition

Laurence Stamford; Adisa Azapagic

doi:10.1016/j.scitotenv.2019.06.343

Environmental impacts of copper‑indium‑gallium-selenide (CIGS) photovoltaics and the elimination of cadmium through atomic layer deposition

Sci Total Environ. 2019 Oct 20:688:1092-1101. doi: 10.1016/j.scitotenv.2019.06.343. Epub 2019 Jun 23.

Authors

Laurence Stamford¹, Adisa Azapagic²

Affiliations

¹ School of Chemical Engineering and Analytical Science, The Mill, Sackville Street, The University of Manchester, Manchester M13 9PL, UK. Electronic address: Laurence.stamford@manchester.ac.uk.
² School of Chemical Engineering and Analytical Science, The Mill, Sackville Street, The University of Manchester, Manchester M13 9PL, UK.

PMID: 31726540
DOI: 10.1016/j.scitotenv.2019.06.343

Abstract

Thin-film technologies have been part of the rapidly-expanding solar photovoltaics (PV) market for many years, led by cadmium-telluride (CdTe) and copper‑indium‑gallium-selenide (CIGS). However, their environmental impacts remain largely unknown, particularly considering state-of-the-art CIGS manufacturing techniques. This study estimates the life cycle environmental impacts of CIGS PV installations in the UK and Spain, including balance-of-system components, using real manufacturing data. It also analyses newly-developed CIGS, replacing the cadmium sulphide (CdS) buffer layer with zinc oxysulphide (Zn(O,S)) via atomic layer deposition (ALD). The results show that UK installations have 72% higher impacts than those in Spain, including climate change (25.1 vs 14.6 g CO₂ eq./kWh). The inverter and electrical components are the main contributors (46% on average), followed by the PV modules (41%). In comparison to CdTe, mono-Si and multi-Si PV, CIGS has 6%-90% lower impacts in 16 out of 18 categories, including climate change (16%-50% lower). However, metal depletion is five times higher, and land use 12%-31% greater. The replacement of CdS has a small but positive effect, demonstrating that cadmium can be eliminated from the CIGS life cycle without environmental penalties. These results will be of interest to PV manufacturers and policy makers, indicating improvement opportunities and areas for policy intervention.

Keywords: Atomic layer deposition; CIGS; Environmental sustainability; Life cycle assessment; Photovoltaics; Solar energy.