Earth and our Moon intercept tiny fractions of the high-quality power generated by the Sun. Earth's oceans and atmosphere, modified by the life of the growing biosphere, moderate the day-night swings of temperature to an average global temperature of 15C (59F). Our moderating biosphere enabled humans to evolve to where our industries now consume increasing parts of the ancient (i.e., fossil fuels, high-grade minerals, and others) and modern biosphere (i.e., atmospheric oxygen, clean water, and others) and are significantly degrading the modern atmosphere, oceans, and biosphere to provide us with thermal and electric power and other goods and services. Our ancient terrestrial resources cannot provide us sustainable economic growth and security. Natural sunlight on Earth cannot enable a growing economy. At Earth's surface, sunlight is unpredictably irregular and requires massive power collection, electric distribution, and power storage to provide somewhat reliable commercial electric power. In contrast, sunlight falls reliably onto the Moon, unimpeded by atmospheric clouds, rain, fog, and dust or life. Very low-mass solar-power collectors constructed on the Moon from lunar soils can convert the collected sunlight into beams of microwave photons that can be directed to receivers on Earth. These receivers can efficiently output low-cost commercial electric power. The beams dependably pass through all atmospheric conditions and can be provided night and day. Electric energy costs can decrease by a factor of 10 or more. This massless electric power enables a growing global economy that is sustainable and clean.