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This study aims to evaluate and compare the environmental impacts of stand-alone photovoltaic (PV) systems with storage installed in Burkina Faso using the life cycle assessment (LCA). SimaPro 9.4 software, Ecoinvent 3.7 database, and the ReCiPe 2018 (H) median method were used to assess the environmental impacts. The functional unit considered is “1 kWh of electricity produced in Burkina Faso by a stand-alone PV system”. Four scenarios combining two variables, battery technology (lead-acid and lithium-ion) and end-of-life management (landfill and recycling), were studied to assess 08 environmental indicators. The results show that production and end-of-life management of batteries and PV modules are the main contributors to the environmental impact, with batteries' impact ranging from 73 to 98 % for lead-acid and 50–68 % for lithium-ion batteries. Compared to landfilling, recycling significantly reduces environmental impacts, achieving reductions of 17–77 % for lead-acid batteries (LABs) and 3–99 % for lithium-ion batteries (LIBs). The comparison between scenarios indicates that the LABs PV system with landfilling generates significantly higher scores across all impact categories than LIBs PV scenarios. Specifically, it shows scores over 10 times higher for human carcinogenic toxicity, 5 times higher for human non-carcinogenic toxicity, and 2 times higher for freshwater ecotoxicity. Despite extending battery lifespan, the sensitivity analysis revealed that landfill PV systems remain the most polluting, while in recycled scenarios, this extension brings them closer to the environmental performance of LIBs PV systems. The use of LIBs in photovoltaic systems is more environmentally friendly than that of LABs, regardless of the end-of-life scenario.

Dechlorination of Polychlorinated Biphenyls (PCBs), carcinogenic substances used as oil in electrical transformers, remains an environmental challenge. This study aims to investigate the dechlorination of PCBs-contaminated transformer oils using microwave catalytic (Fe0, glycerol) pyrolysis and to study the kinetics of PCBs dechlorination. After determining the composition of PCBs-contaminated oil using Gas Chromatography with an Electron Capture Detector (GC-ECD), response surface methodology through a central composite design was used to optimize dechlorination factors (irradiation time, microwave power, NaOH). Finally, a kinetic study of PCBs dechlorination under optimal conditions was conducted. The results showed that the concentration of PCBs in the studied transformer oil was 526 ± 0.01 mg/kg, composed of 14 congeners, with a dominance of hexa-PCBs (70 %) and penta-PCBS (18 %). The optimal PCBs dechlorination yield of 98.87 % was obtained under the following conditions: microwave power of 700 W, irradiation time of 8 min, and 0.3 g of NaOH. The kinetic study showed that PCBs degradation under optimal conditions follows a first-order reaction. These findings suggest that microwave-assisted catalytic pyrolysis is an effective and promising method for PCBs dechlorination in transformer oil, offering a potential solution for environmental remediation.

Abstract This work aims to determine the Energy Payback Time (EPBT) of a 33.7 MWp grid-connected photovoltaic (PV) power plant in Zagtouli (Burkina Faso) and assess its environmental impacts using the life cycle assessment tool according to ISO 14040 and 14044 standards. A “cradle to grave” approach was used, considering 1 kWh of electricity produced and injected into the national grid over 25 years as a functional unit. In addition to the baseline scenario, the other simulated scenarios combining three variables, module technology (mono c-Si, poly c-Si, and CdTe), type of mounting structure (aluminum and steel), and end-of-life treatments (landfill and recycling) were considered. SimaPro 9.4 software and the ReCiPe 2016 Midpoint (H) evaluation method were used for the calculations considering four environmental indicators. A sensitivity analysis of the change in the electricity mix was also performed. Results showed that the EPBT of the scenarios varies between 1.47 and 1.95 years, with the shortest and longest corresponding to scenarios 4 (CdTe modules, steel mounting structure, and recycling as end-of-life treatment) and scenario 3 (mono c-Si modules, aluminum mounting structure, and recycling as end-of-life treatment), respectively. All the EPBT scenarios studied can be considered acceptable given the long lifetime of PV systems (25 years). The following environmental impact results were obtained: climate change 37–48 CO2-eq kWh-1, freshwater ecotoxicity 4–11 g 1,4-DCB kWh-1, mineral resource scarcity 0.4–0.7 g Cu-eq kWh-1 and 11–13 g oil-eq kWh-1 for fossil resource scarcity. Scenario 3 (mono c-Si modules, aluminum mounting structure, and recycling as end-of-life treatment) dominates all environmental indicators studied except freshwater ecotoxicity, which is dominated by scenario 4 (CdTe modules, steel mounting structure, and recycling as end-of-life treatment). The sensitivity analysis showed that the change in the electricity mix could reduce around 30% the EPBT, climate change, and fossil resource scarcity. Considering the environmental indicators studied, using CdTe modules manufactured in a country with a less carbon-intensive electricity mix, using galvanized steel as the mounting structure, and completely recycling components at the end of their lifetime is the most environmentally friendly scenario. However, particular attention needs to be paid to the land occupation that this plant could generate.