Why sustainable power is unsustainable

Renewable energy needs to become a lot more renewable

…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 cells can achieve efficiencies greater than 40%.

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