User:KaylaCarleton/sandbox

Edits to intro to make the intro more acessable to a general reader will be underlined, the rest of this paragraph is copied from the wiki article:
Cadmium telluride (CdTe) photovoltaics describes a photovoltaic (PV) technology, or solar cell techology, that is based on the use of cadmium telluride in a thin semiconductor layer designed to absorb and convert sunlight into electricity. Cadmium telluride PV is the only thin film technology with lower costs than conventional solar cells made of crystalline silicon in multi-kilowatt systems.

On a lifecycle basis, CdTe PV has the smallest carbon footprint, lowest water use and shortest energy payback time of any current photo voltaic technology. CdTe's energy payback time of less than a year allows for faster carbon reductions without short-term energy deficits.

The toxicity of cadmium is an environmental concern mitigated by the recycling of CdTe modules at the end of their life time. Though there are still uncertainties regarding the recycling of CdTe modules and the public opinion is skeptical towards this technology. The usage of rare materials may also become a limiting factor to the industrial scalability of CdTe technology in the mid-term future. The abundance of tellurium—of which telluride is the anionic form—is comparable to that of platinum in the earth's crust, as such it is somewhat rare, and this rarity contributes significantly to the module's cost.

CdTe photovoltaics are used in some of the world's largest photovoltaic power stations, such as the Topaz Solar Farm. With a share of 5.1% of worldwide PV production, CdTe technology accounted for more than half of the thin film market in 2013. A prominent manufacturer of CdTe thin film technology is the company First Solar, based in Tempe, Arizona.

Recycling
Photovoltaic modules can last anywhere from 25 – 30 years. Improper disposal of PV modules can release toxic materials into the environment. Only three methods of high value recycling are industrially available for thin-film PV modules, as of 2013. SENSE (Sustainability EvaluatioN of Solar Energy systems) and RESOLVED (REcovery of SOLar Valuable materials, Enrichment and Decontamination) are European funded procedures. SENSE relies on mechanical, chemical and thermal treatments. RESOLVED relies on mainly mechanical treatments. The final method, First Solar, relies on mechanical and chemical processes. Mechanical methods of recycling are more environmentally friendly as they do not rely on the use of chemicals.

Materials that can be recovered in the recycling process include metals, mounts, glass, and, in high value cases, the whole PV module.

As of 2013 the recycling costs for CdTe modules are higher than the re-sale of recycled materials. However, possible future recycling methods may decrease in cost through reduction of expensive and environmentally unfriendly processes. Promising future recycling methods include vulcanization-vacuum distillation and the Double Green Process. Vulcanization-vacuum distillation has been suggested as a possible recycling process to obtain Te and can recover Te with purities up to 99.92%. The Double Green Process consists of almost entirely mechanical processes.

Environmental Impact
Photovoltaics can assist in reducing toxic emissions and pollution caused by fossil fuels. Emissions from fossil fuels that impact global climates such as Nitrogen Oxide (NOx), Carbon Dioxide (CO2) and Sulfur Dioxide (SO2) are not emitted from PV. A single gigawatt-hour of electricity produced from PV would decrease the emissions of SO2 by 10 tons, NOx by 4 tons and CO2 by 1000 tons when compared to coal.

CdTe cells are considered to be both toxic and carcinogenic when inhaled or ingested as Cd is a toxic compound by the US Occupational Safety and Health Administration. Workers in processing facilities may be exposed to, and inhale, fine particles or fumes of Cd.

CdTe production facilities may cause environmental issues when there are accidents in high efficiency production or from by-product exhaust in less efficient production methods.

During a module’s lifespan it will not release any particles or vapors if used as intended. The only way for a completed module to release dust or vapor is by being lit aflame or ground into fine dust. When exposed to temperatures of approximately 1100 °C in lab tests around 0.4% to 0.6% of the Cd content was released.

The overall Cd air emission estimates can range from 0.02 to 0.5 grams per gigawatt-hour.

Early CdTe modules failed elution tests, however more recent models can pass some elution tests. Despite the small amounts of Cd that may leach out, CdTe modules have low overall leachability as the hazardous materials within them are encased within two layers of glass. Despite their low leachability, CdTe modules have very poor biodegradability.