ALMOST 150 years after photovoltaic cells and wind turbines were invented, they still generate only 7% of the world’s electricity. Yet from being peripheral to the energy system just over a decade ago, they are now growing faster than any other energy source and their falling costs are making them competitive with fossil fuels. It is no longer far-fetched to think that the world is entering an era of clean, unlimited and cheap power.
There is a $20trn hitch, though. To get from here to there requires huge amounts of investment over the next few decades, to replace old smog-belching power plants and to upgrade the pylons and wires that bring electricity to consumers. Normally investors like putting their money into electricity because it offers reliable returns. Yet green energy has a dirty secret.