A European consortium consisting of Italian energy agency Enea and the French Alternative Energies and Atomic Energy Commission, among other entities, has developed a plan to build a low-emissions pilot line to recover critical and precious metals such as silicon, indium, gallium and silver. The line will be designed to reintroduce new materials and new products into the production cycle.
The French Alternative Energies and Atomic Energy Commission (CEA) is coordinating the Photorama research project, which aims to demonstrate the novel recycling process. The onjective is to recycle raw materials from end-of-life PV products while maximizing recovery rates of raw materials from PV panels compared to conventional technologies. Photorama also aims to enable the use of recycled materials with a circular economy approach to the production of secondary raw materials.
The project envisages the construction of a low-emissions pilot line to recover critical and precious metals such as silicon (Si), indium (In), gallium (Ga), silver (Ag). It will then reintroduce them into the production cycle as new materials or new products.
The pilot line will work in three different steps: module auto disassembly, the smart separation of the components, and the innovative recovery of the materials.
“The process starts with a new delamination technique based on a wire diamond technology, developed and patented by the CEA,” Enea researcher Massimo Izzi told pv magazine. “With this technology, it will be possible to separate a module’s glass, backsheet, and cells in a single process, in such a way that the single parts of the module can then be treated individually for the recycling phase.”
Chemical-physical processes based on supercritical fluid (SCF) coupling CO2 and H2O fluids will then be used to allow a high recovery rate material without resorting to the current and inefficient shredding techniques through which the cells, which are the valuable parts of modules, end up in a recovery chain of low economic value – so-called “down-cycling.”
The pilot line may also be used to recycle thin-film PV modules. The process will be based on technology patented by Germany’s Lux Chemtech. It will facilitate the high solubility of indium and gallium through methane sulfonic acid (MSA) in CIGS panels. The technique can also be used for heterojunction technology, in which silicon and indium are electrochemically isolated after dissolution in MSA.
After the entire recycling process is finished, the unbroken glass will be remastered for direct use in the solar industry, while silver will be converted into conductive inks for screen printing or electrically conductive adhesives to be tested and qualified in PV factories. Silicon will be treated to obtain different purities for use as silicon feedstock in PV manufacturing, or as a sputtering target. Indium will be used in thin-film deposition to be tested and qualified in PV manufacturing. Gallium will be processed to fabricate Cu-Ga or Cu-In-Ga targets used in CIGS-CIS thin-film PV manufacturing.
The pilot line is expected to reach a technology readiness level (TRL) of seven. The TRL measures the maturity of technology components for a system and is based on a scale from one to nine, with nine representing mature technologies for full commercial application. According to Izzi, the pilot line will allow the recovery of the metals from the panels with a degree of purity that has never been achieved before. “It is one of the more advanced and efficient recycling processes in the world,” he said.
The development of the new recycling process will be done in conjunction with testing in a real factory environment. Enel Green Power will provide the modules to be recycled and will use the recycled raw materials in solar cell and module production.
“Our technique should reduce solar module recycling costs thanks to the innovative technology steps, and the implementation of Photorama recycling scheme would unlock already more than 100,000 tons of valuable secondary raw materials by 2030,” Izzi said.
The consortium also includes Spanish PV equipment supplier Mondragon Assembly, Norwegian research entity Sintef, Belgian flat glass processor Maltha, Spanish research company Idener, and Lux Chemtech.
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