2.5 The Hydropower Resource

The overall technical and economic potential for hydropower globally is available from some literature sources. However, the accuracy of these estimates is open to debate. In many cases country-level estimates of technical or economic potentials have been calculated using different criteria and combining these results means the totals are not directly comparable. Efforts to improve the mapping of the global hydropower resource are ongoing, but further work is required and should be encouraged.

However, taking into account these uncertainties, it is clear that the hydropower resource is very large, with many parts of the world being fortunate enough to have large resource potentials (Figure 2.4). Virtually all regions have some hydropower resources although these resources are sometimes concentrated in a small number of countries and are not always located adjacent to demand centres.


Source: WEC, 2010.


Source: WEC, 2010.

The total technical hydropower resource potential depends on a number of critical assumptions in addition to average inflows into a catchment area. However, despite the uncertainty around the calculations, the estimated technical potential for hydropower is as much as 15 955 TWh/year or 4.8 times greater than today's production of hydropower. Estimates of the economically feasible hydropower capacity are not comprehensive enough to provide global estimates, but Table 2.2 presents data for a number of countries with important hydropower resources.

What the economically feasible hydropower potential is for a given country is a moving target. The cost of alternative generation options, which sets the limit at which the LCOE of a hydropower project would be economically feasible, as well as the costs of developing hydropower projects (e.g. through advances in civil engineering, cost reductions for equipment), will change over time. The simple analysis in Table 2.2 also highlights the limitations of some of the available data. The very high ratio of economic to technically feasible resources for some countries tends to suggest that only hydropower resources that have already been examined in detail have been included in the analysis. In other cases, the reason is that the country does have very economic hydropower resources.

Further work to better characterise the hydropower resource under standard definitions would help improve the comparability of resource estimates between countries and with other renewable power generation options. The efforts underway to achieve this should be encouraged.

Africa remains the region with the lowest ratio of deployment-to-potential, and the opportunities for growth are very large. However, in Africa complicated competing priorities and concerns mean that hydropower development is not straightforward. The impact of hydropower development on local populations, their impacts on water use and rights, as well as issues over the biodiversity impacts of large-scale hydropower developments, mean that significant planning, consultation and project feasibility assessments are required. This is often required to take place in consultation with countries downstream, given the importance of Africa's rivers to the water supply of each country. Only once all major concerns are addressed can projects move to the detailed design phase and look to secure financing. The critical issue in Africa, and other regions, of the allocation of water rights between countries and different users within countries can be a significant delaying factor in getting project approval and funding. Growing populations and increasing water scarcity in some regions mean that these issues are complex and potentially divisive, but, without agreement, development is unlikely to move forward.

14 This is based on taking the theoretical total hydropower generation that could be achieved in a country by using all natural inflows as if they dropped to sea level and then assuming what proportion of this could technically be converted to hydropower with today's technologies. However, it is not known for certain whether all of the compiled data sources adhered to this methodology so the totals must be treated with caution.