Tuesday, February 12, 2013

Toxic solar?

Is clean really clean? How about the waste produced in the manufacture process? Or the water required? Can we find a different route to clean energy? Do we have a benefits vs. hazards chart for assessment of new technology?

Only in four years, between 2007 and 2011, the solar panel manufacturers in California produced 46 million toxic wastes, of which they were able to ship only three percent to other states, the remaining 97% still need a home. Solar cell manufacturers have a real problem in their hands disposing of the hazardous waste—millions of pounds of polluted sludge and contaminated water.

Solar cell manufacturing technique utilizes plenty of water that becomes toxic in the process, generating a thick sludge composed of metals and other toxins in water. That sludge must be treated by expensive water treatment equipment, before the water can be released in nature.
Solar cell manufacturers normally send the toxic sledges to special water treatment plants in far away states, transporting it by truck or rail. Dustin Mulvaney, a San Jose State University environmental studies professor who analyses carbon footprint of energies from various sources such as solar, biofuel, and natural gas commented, “It would take one to three months of generating electricity to pay off the energy invested in driving those hazardous waste emissions out of state.”

There is, however, positive news breaking all the time in the frontier of solar cell manufacturing technology. New processes continually reduce carbon foot prints. Not so long ago, solar cells used to have efficiency of three to five percent. In January this year, a new world record for solar cell efficiency has been claimed by a team of scientists led by Ayodhya N. Tiwari that also included PhD students Adrian Chirila and Fabian Pianezzi, at Empa, the Swiss Federal Laboratories for Materials Science and Technology.
The new product is thin film solar cells based on flexible polymer foils. This has pushed solar cell efficiency to over twenty percent for the first time. These solar cells are based on CIGS semiconducting material (copper indium gallium di-selenide). This new process will significantly reduce cost of solar cells production, and will also bring down carbon foot print through increase of efficiency in conversion of light to electricity.

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