By Olga Griffith
Renewable energy generation such as solar is an important development for the planet. Many countries are currently pursuing environmentally friendly energy generation and setting up target timeline to become fossil fuels free. In this chase after renewables, development of solar technologies is accelerated, and all of the solar is claimed to be green. Among various types of solar generation – Si, CIGS, CdTe, OPV, III-Vs (such as GaAs, GaInP, GaAlAs), Perovskites, Quantum Dots, and CZTS, organic solar technology stands out as truly green: abundant non-toxic materials, benign and safe manufacturing and packaging.
The competitive performance and lifetime, costs trends of manufacturing placed Si-PV tech at the top of the large-scale PV market. Despite the positive outcome of using solar energy generation versus fossil fuels, the hazards of manufacturing processes must be taken into account when claiming PV technology to be green. On July 19th and 20th of this year five flash explosions occurred at the GCL polysilicon plant in Xinjiang China across the fabrication facility in a chain-like reaction leading to “more than 10% of the global supply of the solar raw material out of production” as reported earlier by PV magazine and Bloomberg Green. No details of any casualties as a result of this incident have been reported.
The main cause of explosions is a problem with the distillation unit that is used to purify Si. Purification of Si involves high temperatures and large volume of toxic gas (trichlorosilane, principle precursor to ultrapure polysilicon) that reacts violently with moisture when exposed to air. Polysilicon plants have experienced explosions across the globe over the years. Here are few more examples: REC Silicon plant in WA, USA had an explosive leak of trichlorosilane in June of 2012, Mitsubishi Materials Yokkaichi polysilicon plant in Japan had an explosion incident due to trichlorosilane leak in January of 2014, Wacker Polysilicon plant in TN, USA had an explosion incident in September of 2017 releasing large amount of hydrochloric acid into the air.
In contrast to Si manufacturing, organic PV fabrication is safe and environmentally friendly for all organic materials involved (small molecule or polymer), making OPV tech actually green.