According to studies of our energy future carried out by oil giant Shell, the introduction of alternative sources of energy can go a lot faster than predicted by organisations such as the World Energy Council and the International Energy Agency. In its scenario for Sustained Growth, the Shell planning group foresees an average growth in energy demand of 2% a year. In the year 2000, renewable sources of energy, among them wind power, will produce 15% of demand, predicts Shell. Sixty years later, renewables will account for 65%. In a second scenario, Dematerialisation, the projected growth in demand for energy is put at just 1% a year. Subsequently the relative growth of the use of renewable sources is even faster. One conclusion Shell draws from it studies is that because the replacement of fossil fuels is going to be much faster than expected, there is no need for a carbon dioxide tax. The market will do the work, they believe.