Globally, the potential of geothermal far exceeds that of all other renewable sources
together, although investment in the other sources to date has far exceeded investment in
geothermal. World Energy Assessment estimates in 2000 for the global potential of all
renewables (EJ/yr) were Geothermal 5000, Solar 1575, Wind 640, Biomass 276, Hydro 50,
giving a total of 7541 (UNDP, 2000). When installed, geothermal plants have a far higher
capacity factor than other sources (solar depends on the level of direct insolation, wind
power on wind, etc.); estimates (REN21, 2009) give wind-power 21%, solar PV 14% but
geothermal is at least as high as 75% and often more than 95%, given that once a plant is
established it operates continuously except for routine down-time for maintenance and rare
break-downs