To put the choices into perspective, let us look briefly at the potential and limitations of each source of electric power, beginning with 'renewables'.
Hydro-electric generating facilities have the attraction of providing electricity without polluting the atmosphere.
They harness the energy of falling water, which can occur naturally, but more often has to be engineered by the construction of large dams with lakes behind them.
The advantages of hrdro-electricity have long been appreciated and today it provides 16% of the world's power.
However, for electricity generation, solar power has limited potential, as it is diffuse and intermittent.
While it can be concentrated, solar input is interrupted by night and by cloud cover, which means that solar electric generation plant can typically only be used to a small proportion of its capacity.
The challenge today is to move away from our heavy dependence on fossil fuels and utilise non-carbon energy resources more fully.
Such a population increase will have a dramatic impact on energy demand, at least doubling it by 2050, even if the developed countries adopt more effective energy conservation policies so that their energy consumption does not increase at all over that period.
Today in the industrial countries of the world, we use between 150 and 350 gigajoules* per person each year, an increasing proportion of it in the form of electricity.
*Joule (J) - A unit of energy Megajoule (MJ) = 10 Joules.
Wind, like the sun, is 'free' and is increasingly harnessed for electricity.
About 238,000 megawatts capacity had been installed around the world at the end of 2011.