This paper addresses the role of power from space for use on earth in the next century. It synopsizes the problems associated with our present practices of supplying power for the world in the face of a projected increase in demand and notes the need to reduce the use of fossil fuels. The probable shortfall by the middle of the next century is estimated and options for earth-based and space-based sources of energy are examined. The paper concludes that energy obtained from space by solar power satellite is a viable and necessary way of meeting a significant part of the world's needs in the next century. Furthermore, energy from such a source will contribute to these needs in a way that would be gentle to the earth If this conclusion is valid, then the topic must be placed on the agenda of the world's energy and aerospace communities and promoted as a significant part of what space-faring can do for humankind.