Wind turbines convert the kinetic energy of moving air into electricity as wind spins blades connected to a generator, but turbines only make economic sense in locations with consistently strong wind speeds. Hydropower generates electricity from flowing or falling water turning a turbine, ranging from large dams such as Ethiopia's Grand Ethiopian Renaissance Dam to small and micro-hydro systems that can power individual rural communities without the scale of a major dam. Geothermal energy, which taps heat from underground reservoirs, is another option in specific geological zones -- Kenya's Olkaria complex is Africa's largest geothermal power facility -- while biomass and biogas systems convert agricultural or organic waste into usable energy.