Working Group III: Mitigation

Other reports in this collection Renewable Energy Conversion Technologies

Natural energy flows vary from location to location, and make the techno-economic performance of renewable energy conversion highly site-specific. Intermittent sources such as wind, solar, tidal, and wave energy require back-up if not grid connected, while large penetration into grids may eventually require storage and/or back-up to guarantee reliable supply. Therefore, it is difficult to generalize costs and potentials. Hydropower

Hydroelectricity remains the most developed renewable resource worldwide with global theoretical potential ranges from 36,000 to 44,000TWh/yr (World Atlas, 1998). Approximately 65% of the technical hydro potential has been developed in Western Europe, and 76% in the USA. This indicates a limit caused by societal and environmental barriers. For many developing countries the total technical potential, based on simplified engineering and economic criteria with few environmental considerations, has not been fully measured. The economic potential resulting from detailed geological and technical evaluations, but including social and environmental issues, i s difficult to establish because these parameters are strongly driven by societal preferences inherently uncertain and difficult to predict. A rate of utilization between 40% and 60% of a region’s technical potential is therefore a reasonable assumption and leads to a global economic hydro-electricity potential of 7,000 to 9,000TWh/yr (see Table 3.30).

Numerous small (<10MW), mini (<1MW) and micro (<100kW) scale hydro schemes with low environmental impacts continue to be developed globally. The extent of this resource, particularly in developing countries such as Nepal, Oceania, and China, is unknown but likely to be of significance to rural communities currently without electricity.

Large-scale hydropower plant developments can have high environmental and social costs such as loss of fertile land, methane generation from flooded vegetation, and displacement of local communities (Moomaw et al., 1999b). At the 18,200 MW Three Gorges dam under construction in China, 1.2 million people have been moved to other locations. Another limitation to further development is the high up-front capital investment which the recently privatized power industries are unlikely to accept because of the low rates of return.

The remote locations of many potential hydro sites result in high transmission costs. Development of medium (<50MW) to small (<10MW) scale projects closer to demand centres will continue. In countries where government or aid assistance is provided to overcome the higher investment costs/MW at this scale, power generation costs around US$0.065/kWh will result (UK DTI, 1999). Mini- and micro-hydro low head turbines are under development but generating costs at this scale are likely to remain high, partly as a result of the cost of the intake structure needed to withstand river flood conditions. Even at this small scale, environmental and ecological effects often result from taking water from a stream or small river and discharging it back again, even after only a short distance.

Table 3.30: Annual large hydroelectric development potential (TWh/yr)
  Theoretical potential
Technological potential
Economic potential
  TWha TWhb TWha TWhb TWha TWhb
Africa 3,307 3,633 1,896 1,589 815 866
North America 5,817 5,752 1,509 1,007 912 957
Latin America 7,533 8,800 2,868 3,891 1,198 2,475
Asia (excluding former USSR) 15,823 14,138 4,287 4,096 1,868 2,444
Australasia 591 592 201 206 106 168
Europe 3,128 3,042 1,190 942 774 702
Former USSR 3,583 3,940 1,992 2,105 1,288 1,093
World 39,784 39,899 13,945 13,839 6,964 8,708
a World Atlas, 1999
b International Water Power & Dam Construction, 1997

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