Almost 80 percent of the world’s energy could come from renewable energy sources by 2050, according to the IPCC’s Special Report on Renewable Energy Sources and Climate Change Mitigation.

The report’s super-green scenario assumes we become so energy efficient that the predicted 9-billion-strong population of 2050 uses less energy than 7 billion of us do today — 407 exajoules per year, compared with 490 exajoules.

However, without green support we could consume 749 exajoules by 2050, with only 15 per cent coming from renewables, the report suggests.