Renewable energies have been the primary energy source in the history of the human race. During the last 200 years, industrialized countries have shifted their energy consumption toward fossil fuels. Contemporary electric power generation is based on non-renewable resources such as oil, coal, and nuclear power. New efficient and cost-effective small-scale renewable energy generation options are commercially available today. Market distortions are to be overcome in order to make renewable energies cost-competitive in today’s economic environment. Social, environmental and also economic reasons will reverse the worldwide primary energy use back to renewables and thus reapproach a sustainable economic system based on traditional and new high-tech technologies.