Peak Oil News >> Hydrocarbon Alternatives >> Solar Energy's Red Queen

Keith_McClary writes: Worldwide, the total installed capacity of photovoltaic panels increased by 36 percent in 2006. Alternative-energy advocates would, ideally, like to see such rates maintained so that photovoltaic cells could displace a large fraction of the fossil fuels being used to generate electricity. The rub is that with an energy payback time of three years, growing the industry at this pace requires more energy than all the existing photovoltaic cells produce. That is, even if you could somehow harvest all the energy produced from every last photovoltaic cell in one year, the total wouldn't be sufficient to produce the next year's crop of panels. As Lewis Carroll's Red Queen said in Through the Looking Glass, "Now here, it takes all the running you can do, to keep in the same place."

Andy Black, chief executive officer of OnGrid Solar Energy Systems, a San Jose company, pointed out this particular Red Queen effect in a presentation to the Solar World Congress in 2005. "It's sort of a mathematical oddity," says Black. "We've got this wonderful, clean industry that's actually using coal to power it." Were the growth rate more modest, of course, such photovoltaic systems would produce more energy than is being used to fuel their production. But Black says, "We're not going to make a difference unless we grow fast."

Another solar-energy advocate to express such concerns is Michael Graetzel, a professor of chemistry at the Ecole Polytechnique Federale de Lausanne in Switzerland. Two decades ago, Graetzel began work on a way to produce solar cells without silicon. He and his colleague Brian O'Regan published an influential paper in Nature showing how this could be done in 1991. The "Graetzel" or "dye-sensitized" solar cell uses a combination of titanium dioxide (a component found in many paints) and an organic dye molecule, often a compound containing ruthenium, which are together immersed in a liquid electrolyte. A. C. Veltkamp of ECN Solar Energy, an independent photovoltaic-research firm in the Netherlands, has estimated that such dye-sensitized cells installed in southern Europe would have an energy payback time of only a half-year or so.