A main drive for developing reliable sources of renewable energy is the fast-growing worldwide energy demand with consequent depletion of fossil fuels, which supply over 85% of the present energy needs. Among the renewable energy sources used today (such as concentrating solar power, solar cells, wind, geothermal, hydropower, and biomass), concentrating solar power (CSP) is the only technology that can supply several times the world's energy requirements, since it has viable, efficient, and available one-day energy storage methods. Storage systems for other renewable sources, such as photovoltaic and wind, are much less efficient and more expensive. There also is not enough usable land for growing sufficient biomass. CSP plants have to be installed in deserts, because clouds and rain strongly lower their efficiency. Suitable deserts are one or two orders of magnitude larger than needed and, aside from some isolated islands, high-efficiency transmission lines can reach all populated areas. Most potential problems for large-scale installation of CSP are political rather than technical. However, since solar energy is the only large-scale renewable source we have for the future, we have to learn how to overcome such obstacles. North America and many other places do not have such obstacles.