BioSolar creates new plastic backing for photovoltaic cells out of cotton and castor beans

Solar energy is touted by some as the solution to the world’s energy woes. But the process of making the various components requires fossil fuels, both for power and for the components themselves, some of which are based on petroleum.

A new company, BioSolar, aims to kick petroleum to the curb, at least in the realm of building solar photovoltaics, cells of crystalline silicon that turn sunlight into electricity. Such photovoltaic cells rely on conventional plastic polymers to provide a protective backing, also known as backsheets. Those plastics are made from – you guessed it – petroleum.

“It’s renewable and you don’t use any petroleum,” says electrical engineer David Lee, president and CEO of the California-based company about the new product. “The real merit is that we can actually reduce the cost of the backsheet compared to conventional petroleum-based backsheet.” Lee claims their backsheets will cost 25 percent less than conventional backsheets, which cost between $0.70 and $1 per square foot.

Already, such backsheets are rising in price, thanks to the recent run-up in world oil costs, at a time when the solar industry is trying to bring down costs to make their technology more competitive with other forms of power generation, such as cheap, plentiful and extremely polluting coal.

BioSolar starts with used cotton rags and turns them into a film of cellulose, a natural fiber. They then blend this film with a type of nylon made from castor beans by Philadephia-based Arkema, Inc. to make the so-called BioBacksheet. Initial testing by the company at the National Renewable Energy Laboratory shows that this flexible plastic backsheet lasts as long or longer than conventional ones, and keeps out just as much moisture.

In addition to keeping away from petroleum plastics, BioSolar also claims not to be using any genetically modified crops in its product – a further boost to its green credibility. But nearly 90 percent of the U.S. cotton crop is so altered, either to resist insects, herbicides or both, according to the U.S. Department of Agriculture. And cotton cultivation still requires tons of pesticides and fertilizers, both of which are derived, in part, from petroleum.

Regardless, if the cotton and castor-based backsheet proves cheaper than the petroleum version it may help remove a bit more fossil sunshine from the new solar energy. “Our goal is to replace all the petroleum plastic out of the solar cells with this bio-based one,” Lee says.

Source

Scientific American, 2008-08-13.

Supplier

BioSolar

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