Climate change, air pollution, water pollution, and increasingly insecure and unreliable energy supplies are among the greatest environmental and economic challenges of our time. Addressing these challenges will require major changes to the ways we generate and use energy. With this in mind, scientists, policy analysts, entrepreneurs, and others have proposed large-scale projects to transform the global energy system from one that relies primarily on fossil fuels to one that uses clean, abundant, widespread renewable energy resources. Here, we analyze the feasibility associated with providing all our energy for all purposes from wind, water, and the sun (WWS), which are the most promising renewable resources. We first describe the more prominent renewable energy plans that have been proposed, and then discuss the characteristics of WWS energy systems, the availability of WWS resources, supplies of critical materials, methods of addressing the variability of WWS energy to ensure that power supply reliably matches demand, the economics of WWS generation and transmission, the economics of the use of WWS power in transportation, and policy issues. We conclude that barriers to a 100% conversion to WWS power are primarily social and political, not technological or even economic. We suggest a goal to produce all new energy with WWS by 2030 and replace all pre-existing energy by 2050. The cost of energy due to a conversion is expected to be similar to that today.
