In developing countries, water is the most important and cost-effective renewable used in power generation. In eleven African nations, hydropower accounts for over 96% of all electricity generated; in South America this figure varies between 40% and 100% depending on the region. There is still considerable potential for increasing the use of hydropower on all continents. One enormous drawback, however, is that the construction of large dams is linked to a variety of social and environmental problems. To cite just one example, between 40 and 80 million people have been displaced or resettled due to the construction of artificial lakes. But dams are not always necessary. By taking advantage of natural geological conditions, electricity can be generated using hydropower without the need for major landscape changes. And small local hydropower stations are perfectly capable of providing a reliable and environmentally sound electricity supply in rural areas. There is considerable scope for expanding hydropower capacity in all parts of the world. To date, only around one quarter of the technically and economically viable potential has been tapped.

From the global perspective, wind energy shows great promise, especially for generating electricity and powering pump-driven water supply systems. Wind power is of course feasible only in areas with reliable winds, such as coastal and mountain regions.

Biomass and geothermal energy

In the form of fuelwood, charcoal or organic waste such as cow dung, biomass still delivers around 80% of all household energy in developing countries. However, its overuse can cause considerable problems: excessive logging leads to soil erosion and falling groundwater tables, and cooking in rooms without smoke outlets gives rise to chronic bronchial disorders. In the future, biomass will continue to be the main source of energy for the poor. But the use of biomass must go hand in hand with sustainable forestry practices, increased fuel efficiency achieved by burning dried wood, smoke extractors/outlets, and the increasing use of agricultural waste. By fermenting waste to produce biogas we can recover considerable amounts of energy. Another promising source of biomass energy is vegetable oil, which can be used for both lighting and fuel. However, this must not be to the detriment of small farmers and the cultivation of staple crops.

The earth’s core is exceedingly hot, with temperatures of between 4,500 oC and 6,500 oC. And this heat energy can be harnessed, especially in areas where the geothermal energy sources are close to the earth’s surface, for example in the East African rift valley, in Central America or in the Pacific region. Geothermal energy is the third largest source of clean electrical power in the world today.