Solar cells in the course does have no emissions, no noise, and energy consumption of clean energy title, but the mainstream today, but ignore the glossy surface of solar cells behind the production process of high pollution, high energy consumption.
First, the high pollution
Solar cell is 90% for crystalline silicon cells, the raw material for polysilicon, silicon metal (industrial silicon) purified from the country are using the chemical method (Modified Siemens): first silicon metal into trichlorosilane, and then fractionation and distillation purification, high purity trichlorosilane (toxic, corrosive and explosive), and ultimately restore from hydrogen; this process is only about 25% of trichlorosilane transfer into polysilicon , and the remaining direct emissions; the most polluted, is a byproduct during the restore process - silicon tetrachloride (an extremely corrosive, toxic liquids that are difficult to save, with acute toxicity due to silicon tetrachloride natural degradation of the silicon tetrachloride dumped or buried, the water will be subject to serious pollution, land will become barren land). This does not include a large number of chlorine and other toxic and flammable and explosive gases.
To produce 1KW solar panels consuming 10Kg polysilicon, silicon tetrachloride produce 80Kg above. Domestic through hydride reduction of the closed-loop process cycle to reduce the emission of silicon tetrachloride is only one; and even by hydride reduction of the closed-loop process cycle, silicon tetrachloride emissions still reached 50%; silicon tetrachloride is a chemical raw material, downstream chemical plant digestion is very limited. A small part of most domestic polysilicon manufacturers of silicon tetrachloride at low prices sold to downstream manufacturers, part of the store, then secretly buried.
This does not include other accessories post-processing of the silicon. Such as acid and alkali solution used in the texturing process, proliferation of the use of phosphorus oxychloride, the use of PECVD silane, these auxiliary consumption of less than the main material.
As the solar timeliness, sunlight will produce electricity; maintain the power supply must be used to charge storage batteries when the sun without the sun. While the canada batteries mainly in the lead-acid batteries the degree of pollution is considerable.
Second, the high-energy
Silica smelting silicon metal, metal silicon purification for polysilicon, the polysilicon film processing requires a lot of electricity, mainly concentrated in the smelting of the silica, polysilicon ingots and proliferation of these processes; to produce 1KW solar panels need to spend 5800-6000 electricity (national average). We can calculate: the average exposure time of 4 hours / day, the solar cell is the life expectancy of 15-20 years (20 years), the total generating capacity of 1KW solar cells 4x365x20 = 29200KW • h; and consume 6000 kWh compared to electrical energy regeneration than 4.87, it's not even counting the loss of light efficiency as well as the loss of the power inverter and control circuits; far below the hydropower and wind power. If coupled with ultra-white glass, aluminum, steel, cable accessories, power regeneration ratio is quite low.
More than 90 percent of current domestic production of solar panels for export to other countries in enjoying the clean energy, China is suffering from the pain of energy consumption and pollution. China's solar cell production in 2003 10MWp, 50MWp, 2004 200MWp 2005, 2006 400MWp 2007 1088MWp, 2008 2600MWp, 2009 4000MWp; reason why there will be a blowout, just because the only growth on the ZF and only the GDP value. Enterprises only copy or imitate, without making technological innovation, lack of supervision and weak environmental awareness is another important cause of high pollution and high energy consumption.
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