Global anthropogenic selenium cycles for 1940-2010

Selenium plays an important role in emerging thin film solar energy technologies. As solar energy is expected to have a larger share in the world's future energy portfolio, the long-term availability of selenium becomes a potential concern, yet no global cycles have ever been generated. In this work, the global cycles, stocks, and flows of selenium are characterized for the entire time period 1940-2010 by using principles of material flow analysis (MFA). The cycles present information on the production, fabrication and manufacturing, use, and resource management stages during that period. The results of the analysis show that during 1940-2010 approximately 90 Gg of refined selenium was produced and entered into fabrication and manufacturing worldwide. 60 Gg of this amount (two-thirds!) was dissipated into the environment through end-uses such as chemicals, pigments, glass manufacturing, metallurgical additives, and fertilizer and feed additives. The in-use stock of selenium is estimated at 2.7 Gg as of 2010. Because of data limitations such as proprietary and withheld information, these figures represent informed estimates rather than exact values. Selenium can be recovered from end-of-life electrical and electronic equipment, while for other end-uses recycling is difficult or impossible. One of the ways to buttress supplies of selenium for future technologies would be to deploy recycling schemes for photovoltaics as well as other electronics applications. (C) 2013 Elsevier B.V. All rights reserved.