The photo is sourced from CEAt
Carbon dioxide in a supercritical state is able to penetrate solids. The authors of the study took advantage of this property by infiltrating supercritical CO2 into a sealed polymer containing solar cells. Then the scientists depressurised the polymer, causing CO2 to take on a gaseous state and the polymer to expand and foam. The deformation led to the photovoltaic module separation into different layers, which made it possible to extract silicon and silver. At the same time, the glass used in the module remains intact and therefore is suitable for recycling.
The study carried out with the assistance of the French Alternative Energies and Atomic Energy Commission, continues the cycle of innovations designed to reduce the environmental footprint of solar panel production. Earlier, Rosi Solar company began to use high-temperature pyrolysis – the process of decomposition of organic and inorganic substances under low pressure and lack of oxygen – to separate silicon, copper and silver from the glass of solar cells. In addition to the cost savings, the technology helps to reduce carbon footprint: according to Rosi Solar, production of 1 kg of silicon is associated with 50 kg of carbon dioxide emissions, which is higher than the one for magnesium, aluminum and titanium.
Technologies for recycling materials used in renewable energy will become increasingly in demand as solar panels with lifespan over twenty years are retired. For example, in Japan, the accumulated volume of the used solar panels will reach 170–280 thousand tons by 2036. As the New Energy and Industrial Technology Development Organization (NEDO) estimates, this figure will be equivalent to 1.7% to 2.7% of the total industrial waste that will be accumulated in Japan by 2036.
