http://www.lowtechmagazine.com/2009/06/embodied-energy-of-digital-technology...
if the energy cost of the plastics injection molding is enough to power a 30 watt laptop for 1,000 days (3 years), then clearly, recycling of the plastic, doing exactly the same thing, is *not* doing the environment any favours.
the answer is, (a) instead, to keep that plastic casework in use for as long as possible (for example by allowing the main processor and memory to be continuously upgraded on a rolling basis) and/or (b) develop different casework production techniques that are far more energy-efficient.
l.