Environment & Energy
Related: About this forumFun with Chemistry: Recovering the rare element gallium from dead solar cells.
Last edited Fri Sep 16, 2016, 09:15 PM - Edit history (1)
Last night I was reading several papers in the literature concerned with what the badly screwed future generations might do with all the solar cells we've been manufacturing in recent years, despite the fact that they have failed to do a damned thing to address the accelerating rate of climate change.
The solar industry is tiny and clearly useless despite soaking up trillions of dollars, and there are many rote assumptions that claim they are "green" (as in environmentally benign) and "sustainable" (they can be used indefinitely).
As is the case with many rote assumptions, they are wrong.
The paper to which I will refer here is this one: Separating and Recycling Plastic, Glass, and Gallium from Waste Solar Cell Modules by Nitrogen Pyrolysis and Vacuum Decomposition (Lingen Zhang and Zhenming Xu, Environ. Sci. Technol., 2016, 50 (17), pp 92429250)
Some text from the paper:
...Gallium, as an important strategic resource, has been categorized as one of 14 mineral resources by the European Commission in extreme shortage.(11) The world reserve of gallium has been estimated to be 18 000 tones, which is merely one tenth of gold.(12) In nature, gallium has no ores of its own at all; rather it occurs in trace and minor amounts in various associated minerals types, such as bauxite, zinc, tin, and tungsten ores.(13, 14) Hence, it has led to strong interest for recovery of gallium from wastes. At present, various researches have been developed to recycle gallium. Technologies include acid leaching,(15) organic solvent,(16, 17) chemical precipitation, electrochemistry,(18, 19) and supercritical extraction(20) etc. I.M. Ahmed(21) proposed extracting method by Cyanex 923 (a mixture of four trialkylphosphine oxides) and Cyanex 925 (bis(2,4,4-trimethylpentyl) octylphosphine oxide) in kerosene from hydrochloric acid medium to recycle Ga(III). Although these studies have focused on recycling gallium resource, environmental improvement are still challenging due to limitations on using large volume of acid/alkali/organic reagent with high concentration.
The bold is mine. That bolded remark doesn't sound all that "renewable" to me.
The authors propose nitrogen pyrolysis and vacuum decomposition which is (they say) cleaner. Here's some of their investigation of the "clean" process.
Um...benzene. I'm sure they'll be absolutely safe, since all recycling facilities for electronic waste are absolutely safe.
The arsenic is recovered as diatomic arsenic gas which distills away.
The process is in no way quantitative.
Well, whatever gallium and arsenic remains, we can always take it to a "green landfill."
It's amazing how much handwaving and how many ill thought out beliefs, dogmatic beliefs, get attached to the solar industry, since for many decades it was all theory and no practice.
The practice is quite different. Trillion dollar quantities of resources have been thrown at this industry in the last ten years, with the result that the annual increases in the dangerous fossil fuel waste carbon dioxide is the highest ever observed.
It is expected that in about twenty years, about two million tons of used and dysfunctional solar cells will need disposal on this planet. cf (Sustainable System for Raw-Metal Recovery from Crystalline Silicon Solar Panels: From Noble-Metal Extraction to Lead Removal (Byungjo Jung, Jongsung Park, Donghwan Seo, and Nochang Park*, ACS Sustainable Chem. Eng., 2016, 4 (8), pp 40794083)
Enjoy the coming weekend.
kristopher
(29,798 posts)US Geological Survey,
Sources and Supplies of Commodities Used in Photovoltaic Cells, Page 5
http://pubs.usgs.gov/circ/1365/Circ1365.pdf
U.S. Geological Survey,
Mineral Commodity Summaries, January 2016, Page 64
http://minerals.usgs.gov/minerals/pubs/commodity/gallium/mcs-2016-galli.pdf
Poor Nnadir, I have some really, really bad news for you regarding your effort to put lipstick on the nuclear pig by misrepresenting renewable energy.
They've just confirmed that cancers caused by ionizing radiation have a distinct genetic signature that is different from all other causes of cancer.
Ionizing radiation is a potent carcinogen, inducing cancer through DNA damage. The signatures of mutations arising in human tissues following in vivo exposure to ionizing radiation have not been documented. Here, we searched for signatures of ionizing radiation in 12 radiation-associated second malignancies of different tumour types. Two signatures of somatic mutation characterize ionizing radiation exposure irrespective of tumour type. Compared with 319 radiation-naive tumours, radiation-associated tumours carry a median extra 201 deletions genome-wide, sized 1100 base pairs often with microhomology at the junction. Unlike deletions of radiation-naive tumours, these show no variation in density across the genome or correlation with sequence context, replication timing or chromatin structure. Furthermore, we observe a significant increase in balanced inversions in radiation-associated tumours. Both small deletions and inversions generate driver mutations. Thus, ionizing radiation generates distinctive mutational signatures that explain its carcinogenic potential.
Mutational signatures of ionizing radiation in second malignancies
Sam Behjati, Gunes GundemPeter J. Campbell
Nature Communications 7, Article number: 12605 (2016)
doi:10.1038/ncomms12605
Open Access http://www.nature.com/articles/ncomms12605
http://www.democraticunderground.com/1127105056
How long do you think it is going to take to start getting a handle on the real consequences of nuclear power now that they will no longer be able to hide behind the lack of proof regarding cause and effect?