The hydropower resource

Table 8.1 presents figures for global hydropower potential, broken down by region. The gross theoretical capability figures, shown in column one, represent the amount of electricity that could be generated if the total amount of rain that falls over a region could be used to generate power at sea level (thus utilising the maximum head of water and extracting the most energy). This figure is of little practical use but the second column in Table 8.1 is more useful. This shows how much of the theoretical capability could be exploited using technology available today.

As the table shows, hydropower potential is to be found in all parts of the world. While every region has a significant resource, the largest capability exists in Asia where there is 4875 TWh of technically exploitable capability. At the other end of the scale, the Middle East has 218 TWh.

Not all the technically exploitable capability in any region can be cost effectively utilised. That which can is termed the economically exploitable capability. Of the total technically exploitable capability shown in Table 8.1, 14,379 TWh, just over 8000 TWh is considered to be economically exploitable. This is three times the 2650 TWh of electricity generated by the hydropower

Table 8.1 Regional hydropower potential

Gross theoretical Technically exploitable capability (TWh/year) capability (TWh/year)


North America South America Asia Europe Middle East Oceania




6818 6891 16,443 5392 688 596

>1888 >1668 >2792 >4875 >2706 <218 >232


Source: World Energy Council.

Table 8.2 Regional installed hydropower capacity

Capacity (MW)

Capacity (MW)

Table 8.2 Regional installed hydropower capacity



North America


South America






Middle East






Source: World Energy Council.

Source: World Energy Council.

plants operating around the world today. Thus two-thirds of the global resource remains unexploited.

The actual level of exploitation varies widely from region to region. The World Energy Council estimated in the 1990s that 65% of the economically feasible hydropower potential has been developed in Europe and 55% in North America. In Asia, by contrast the level of exploitation was 18% while in Africa it was only 6%.

So, as already noted, the developed world has taken advantage of much of its hydropower resource while the resource in the developing world remains largely unexploited. Africa, in particular, has some major hydropower sites that could, sensitively developed, provide significantly greater prosperity to regions of that continent.

Today the gross global installed hydropower capacity is just under 700 GW, with another 100 GW under construction.3 Current global hydropower capacity is broken down by region in Table 8.2. In gross terms, Europe has the biggest installed capacity, followed by Asia and North America. The Middle East, probably the world's most arid region, has the smallest capacity. Comparing the numbers in Table 8.2 with those in Table 8.1 confirms that Africa has exploited relatively less of its capability than any other region.

If all the remaining economically exploitable capacity in the world was utilised with the same efficiency as that of current capacity, an additional 1400 GW could be constructed. This would roughly triple the existing hydropower capacity. Exploitation would involve an additional 14,000 power plants with an average size of 100 MW, at a cost of $1500 billion.

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