Climate change, pollution, and energy insecurity are among the greatest problems of our time. Addressing them requires major changes in our energy infrastructure. Here, we analyze the feasibility of providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight (WWS). In Part I, we discuss WWS energy system characteristics, current and future energy demand, availability of WWS resources, numbers of WWS devices, and area and material requirements. In Part II, we address variability, economics, and policy of WWS energy. We estimate that ∼3,800,000 5MW wind turbines, ∼49,000 300MW concentrated solar plants, ∼40,000 300MW solar PV power plants, ∼1.7 billion 3kW rooftop PV systems, ∼5350 100MW geothermal power plants, ∼270 new 1300MW hydroelectric power plants, ∼720,000 0.75MW wave devices, and ∼490,000 1MW tidal turbines can power a 2030 WWS world that uses electricity and electrolytic hydrogen for all purposes. Such a WWS infrastructure reduces world power demand by 30% and requires only ∼0.41% and ∼0.59% more of the world's land for footprint and spacing, respectively. We suggest producing all new energy with WWS by 2030 and replacing the pre-existing energy by 2050. Barriers to the plan are primarily social and political, not technological or economic. The energy cost in a WWS world should be similar to that today. ► Replacing world energy with wind, water, and sun (WWS) reduces world power demand 30%. ► WWS for world requires only 0.41% and 0.51% more world land for footprint and spacing, respectively. ► Practical to provide 100% new energy with WWS by 2030 and replace existing energy by 2050.