According to NewScientist, the Earth has left only a ten-year supply of indium, a key metal in making solar panels efficient enough to actually compete with fossil fuels:
The efficiency of solar cells is measured as a percentage of light energy they convert to electricity. Silicon solar cells finally reached 25% in late December. But multi-junction solar cellsgreater than 40%. can achieve efficiencies
Although touted as the future of solar power, those and most other multiple-junction cells owe their performance to the rare metal indium, which is far from abundant. There are fewer than 10 indium-containing minerals, and none present in significant deposits – in total the metal accounts for a paltry 0.25 parts per million of the Earth’s crust.
Most of the rare and expensive element is 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.
If power from the Sun is to become a major source of electricity, solar panels would have to cover huge areas, making an alternative to indium essential.
Oh, and that hydrogen plan needs more work, too:
A cheap way to generate hydrogen has so far proved elusive. New approaches, such as using bacterial enzymes to “split” water, have a long way to go before they are commercially viable.
So far, fuel cells are still the most effective way to turn the gas into electricity. But these mostly rely on expensive platinum to catalyse the reaction.
The trouble is, platinum makes indium appear super-abundant. It is present in the Earth’s crust at just 0.003 parts per billion and is priced in $ per gram, not per kilogram. Estimates say that, if the 500 million vehicles in use today were fitted with fuel cells, all the world’s platinum would be exhausted within 15 years.
Unfortunately platinum-free fuel cells are still a long way from the test track. A nickel-catalysed fuel cell developed at Wuhan University, China, has a maximum output only around 10% of that a platinum catalyst can offer.
A new approach announced yesterday demonstrates that carbon nanotubes could be more effective, as well as cheaper, than platinum. But again it will be many years before platinum-free fuel cells become a commercial prospect.
[Editor’s Note: This post has been amended since its initial posting.]