The UN Intergovernmental Panel on Climate Change (IPCC) has issued teasers ahead of an upcoming report into renewable energy.
The IPCC says that "close to 80 per cent of the world’s energy supply could be met by renewables by mid-century". However this is derived from the most optimistic possible scenario for renewables, and even then it requires most of the human race to remain in miserable poverty.
Total world energy supply, according to the IPCC, now stands at around 490 exajoules per year at the moment – which chimes fairly well with other previous analyses. The IPCC suggests that no less than 13 per cent of this comes from renewable sources, though once the full report becomes available it will probably turn out that a lot of this is biofuel consumption which may or may not actually be renewable or sustainable. Certainly the US Energy Information Administration figures show that only 7.7 per cent of world energy production comes from renewable electricity generation right now.
The IPCC report apparently examines various scenarios for renewables. Under the most optimistic of these – this will be very optimistic indeed, given the nature of the IPCC and its advisors – renewables could furnish some 314 exajoules per year, about 64 per cent of current production.
The IPCC manages to generate its "close to 80 per cent by 2050" claim by assuming that the human race can actually get by on much less energy than it uses today.
That's probably reasonable enough in the case of Americans, who collectively get through around 100 exajoules each year. It might even be true of Europeans, who use a similar amount collectively despite there being many more of them.
Unfortunately the entire rest of the human race has to share the remaining third of the global energy supply (and most of this goes to the relatively small numbers in the remaining industrialised nations). This means that the vast bulk of the human race use very little energy at all: half a billion in sub-Saharan Africa alone have no access even to intermittent grid electricity, for instance.
All those billions of people, reasonably enough, would like to have light at night, heat when it's cold, cooling when it's hot. They'd like to have functioning transport, safe food storage and cooking, hot baths or showers, laundered clothes. They'd like a decent proportion of jobs outside the subsistence farming sector, and a highly energy-intensive health industry along US or European lines. They'd probably even enjoy a few comparatively unimportant fripperies like some IT equipment and the odd jet flight.
All in all, it seems fair to say that human beings deserve to use, say, two-thirds as much energy as an average European of today does.
Unfortunately for the IPCC report, seven billion people each using as much energy as two-thirds of a present-day European will need supplies of 770 exajoules, not 407 as the IPCC assumes. In a more realistic scenario where the human population continues to climb, energy demand in the industrialised nations continues to rise instead of falling enormously and (hopefully) the world's poor start to get a taste of the good life, supplies in the zettajoule (1000 exajoule) range will be required within decades.
Bearing in mind that the headlining IPCC figure of a possible maximum 314 exajoules from renewables in 2050 will have been massaged upward by every possible means – the other, lower-output scenarios are much more likely – we can see that renewables will be doing well to furnish 20 per cent of world energy supplies by the middle of this century.
Renewables will only ever provide above half the world's supply in some grim future where the great majority of the human race is either wiped out within a generation or remains in grinding, miserable poverty. ®