There's a paradox in the growing global appetite for greener energy. As sales of solar panels and wind turbines increase, so too does the scale of an often-overlooked problem now being stored for future generations. What happens to all the "green" infrastructure when it reaches the end of its life?

When early-generation green technology is replaced, much of it now finds its way into landfill or incinerators. This is not only a blow to waste-reduction efforts, adding hundreds of thousands of tons of rubbish to the global tally every year, but also is also a colossal missed opportunity. Solar panels comprise metals and glass, which, if they were separated and captured, could be reused in the manufacture of other products.

It is possible, through innovative technologies still being developed, to recycle more than 90 percent of a solar panel. But, given the volatility in the value of the resulting raw materials, this is a high-risk sector to develop, and research and development is lacking. Basic recycling schemes do exist, but often focus on two valuable components -- the glass and aluminum frame, for instance -- and discard the rest, including silver, silicon and tin, because it is not yet cost-effective to recycle them.