The fundamental flaw with today’s renewable energy sources is that they utilize non-renewable elements to work, points out an article in NewScientist.
Solar Cells need sillicon which is abundant on earth’s crust, but they are only 25% efficient. The the more efficient cells (upto 40% level) called multi-junction cells use indium, and that is far from abundant.
“There are fewer than 10 indium-containing minerals…accounts for a paltry 0.25 parts per million of the Earth’s crust…used to manufacture LCD screens, an industry that has driven indium prices to $1000 per kilogram in recent years. Estimates that did not factor in an explosion in indium-containing solar panels reckon we have only a 10 year supply of it left.”
Another brilliant idea was generating electricity from hydrogen. Unfortunately though, splitting water cells requires platinum which is even rarer than indium (earth’s crust has .003 parts of platinum per billion, and it would be exhausted in 15yrs).
When it comes to biofuels, most of us know the limitations of ethanol fermented from maize (food shortage), but algae that grows in tanks seems to be a bright solution that is receiving considerable attention.