A comprehensive view of global potential for hydro-generated electricity

In this study, we assess global hydropower potential using runoff and stream flow data, along with turbine technology performance, cost assumptions, and consideration of protected areas. The results provide the first comprehensive quantification of global hydropower potential including gross, technical, economic, and exploitable estimates. Total global potential of gross, technical, economic, and exploitable hydropower are estimated to be approximately 128, 26, 21, and 16 petawatt hours per year, respectively. The economic and exploitable potential of hydropower are calculated at less than 9 cents per kW h. We find that hydropower has the potential to supply a significant portion of world energy needs, although this potential varies substantially by region. Globally, exploitable hydropower potential is comparable to total electricity demand in 2005. Hydropower plays different roles in each country owing to regional variation in potential relative to electricity demand. In some countries such as the Congo, there is sufficient hydropower potential (410 times) to meet all electricity demands, while in other countries such as United Kingdom, hydropower potential can only accommodate a small portion (<3%) of total demand. A sensitivity analysis indicates that hydropower estimates are sensitive to a number of parameters: design flow (varying by -10% to + 0% at less than 9 cents per kW h), cost assumptions (by -35% to +12%), turbine efficiency (by -40% to +20%), stream flow (by -35% to +35%), fixed charge rate (by -15% to 10%), and protected land (by -15% to 20%). This sensitivity analysis emphasizes the reliable role of hydropower for future energy systems, when compared to other renewable energy resources with larger uncertainty in their future potentials.