BioSolar, Inc. has announced that materials derived from cotton and castor beans compose the company’s newly developed BioBacksheet™ product. BioBacksheet™ is intended to be an alternative to the base layer materials already in use on photovoltaic solar cells. Traditionally, such "backsheets" are made from a petroleum-based film, such as Dupont Tedlar™.
Why Castor Beans?
Nylon-11, which is indeed made from an extract of the castor bean, was developed by German scientists as an adaptation to the petroleum shortages of the World Wars. Much of the castor production is from India. Some other common modern applications of the biopolymer N-11 are roller blades and the brightly colored brake lines of trucks. N-11 is tough stuff.The Solar Photovoltaic Industry Depends Highly On the Chemical Industry.
Let's explain this subtopic with an analogy based on paper. Many people think only of plant-derived cellulose when they think of paper; when, in fact, cellulose is only one of several major components likely to be found in modern "papers". Petrochemicals can be a significant part of paper, either as base substrate additive, or in coatings. Example: corrugated boxes used to ship fruits and vegetables are often coated with petroleum wax.
Take this analogy now to photo-voltaics. There are several component layers in any type of solar cell, and the active photo-voltaic layer - silicon being the iconic one - is "sandwiched" and supported with a variety of other material layers (as pictured).
The various non-silicon coatings and support materials in a solar cell matrix must last 20 to 40 years in the sun, cold, rain, and blowing sand. By intent, the various layers of a solar photovoltaic product are tough and not biodegradable. Recyclable perhaps: but not biodegradable.
Several of the composite layers on solar cells are made from chemicals many people would not want in consumer goods. But the fact is, without really tough, complex materials produced by a modern chemical industry, society will not have cost effective solar power. There is no way past that truth.
For an illustration of this point, look at this recent announcement from Dupont regarding their Tedlar-based line.
Due to the continued rapid growth of the photovoltaics industry, DuPont has said that it will more than double the production of its ‘Tedlar’ films, which are used in backsheet applications. DuPont anticipates that the PV market will grow by more than 50 percent per annum over the next few years and expects its sales in the sector could exceed $1 billion within the next five years.
What are the larger implications?
For solar to be "green" the chemical industry too must be green.
The sourcing implications of this are interesting. We'll need to move our thinking beyond casting ingots in the USA vs China. And we'll all have to adjust our thinking past the incorrect "hazard equals risk" paradigm. There's climate risk, which is global. And there is the risk of exposure to hazardous materials, which is personal and local for the most part.
BioSolar projects a cost advantage over traditional backsheets to be in the range of 25 to 50%, although the product is not yet commercially available. Performance specs were not available on the BioSolar website, but it looks as if they have other similar applications in development. Cost, it would seem, is the major advantage.
Via::Yahoo News, BioSolar Reveals Secret of Less Costly Solar Power: Cotton and Castor Beans