Just a 100m-tall windmill tower for every twenty families and we're set
Worryingly, though, the world's population tripled just in the last century. And McElroy's global windfarm is going to take some time to build, as it requires the erection of massive 100m-tall turbines on every single piece of land where the load factor would be better than 20 per cent. By our calculations that would require around 60 million turbines for a present-day world population living at European levels of energy use. We're talking about a turbine as big as a cathedral for every hundred people on the planet; and unlike cathedrals, these things wear out and have to be replaced every couple of decades.
We won't only need turbines, either. Just as the turbines were absolutely everywhere, so too would the high-capacity power grid need to be - covering the vast bulk of the US interior, the Siberian tundra, the Himalayas, the Andes, the Sahara - everywhere that doesn't at the moment have trees, glaciers or buildings on it. The grid will also need to go underwater to cover much of the continental shelf.
Then remember, to have wind turbines and a power grid you must also have transport - good transport, capable of moving huge pieces of machinery. In the all-electric world of the future there won't be much aviation (there isn't any significant amount now which can move wind turbine parts, for that matter). Thus we need high-capacity roads or rails criss-crossing all those mountain ranges and deserts.
Not only will every hundred people alive (twenty or fewer couples of working age) need to save up for a new hundred-metre-tall wind turbine every couple of decades - many of us struggle to pay for a relatively poxy little house on such a timescale - they'll have to pay for the upkeep of a hell of lot more road and power line than Americans or Europeans now do. And these will be expensive roads and powerlines, all the more so as large areas of the world are occasionally subject to days-long calms, meaning that the global grid backbone will need to be very high-capacity indeed so as to carry in huge amounts of juice across continents at need. Or alternatively one would need another world-girdling mega-engineering complex of pumped storage artificial lakes, dams and hydropower machinery.
Even McElroy and his colleagues admit that:
Given the inevitably greater expense of establishing wind farms in remote locations and potential public opposition to such initiatives, it would appear unlikely that these resources will be developed in the near term.
And we haven't even yet got into the fact that McElroy takes his windspeed data from boundary layer analysis, a method which has the advantage of easily covering the whole world but which has produced seriously overblown (cough) windpower results in the past.
So actually there's a big, big further cut to be made to McElroy's bottom-line figures - probably one or more orders of magnitude. But the figures can't take such a cut and remain meaningful. Be nice and say the best that global wind can do is a tenth of what McElroy says - already it's well down below present-day use with us mainly living in poverty and squalor, let alone the human race's actual reasonable requirements.
The people of the world simply can't live decent lives on wind power, QED. Wind power cannot, in fact, provide for the world's current and future energy needs. It seems evident that it's going to be part of the solution, but something else - probably several very large somethings - will be required to go with it. ®