Everyone wants a phone , a computer and a nice air-conditioned room.

With a world population of over 7 billion people – a lot of whom don’t yet enjoy the comforts, convenience and luxury that electricity provides – global power demand is set to shoot up over the next few decades. Demand for electricity will outstrip demand for any other final form of energy, and is likely to be more than two-thirds higher in 2035 than it was in 2011, according to the International Energy Agency (IEA).

Generating that power and getting it to consumers will require huge investment – something like $740 billion a year. And more power cables: the IEA reckons the length of transmission and distribution lines will expand from 69 million kilometres in 2012, to 94 million kilometres in 2035 – enough to circle the Earth 2,350 times.

Rising demand and the closure of old power plants will mean lots of new generating capacity will be needed. A substantial chunk of this will provide greener energy, eating into coal’s dominant share of supply. So while total CO2 emissions will increase because of growth in demand, says the IEA, emissions intensity – a measure of emissions per unit of economic output – should drop.

Most of the electricity-demand growth will happen in emerging economies such as China and India. But the gulf between rich and poor countries in terms of the amount of electricity each person consumes will remain very large. By 2035, only Russia, China and the Middle East will be consuming more than half of the average electricity consumption per person in the OECD. Meanwhile, per capita power demand in sub- Saharan Africa will remain at just 6% of the OECD average.