Abstract: How easy is it get off our fossil fuel habit? What do the fundamental limits of physics say about sustainable energy? Could a typical "developed" country live on its own renewables? The technical potential of renewables is often said to be "huge" -but we need to know how this "huge" resource compares with another "huge": our huge power consumption. The public discussion of energy policy needs numbers, not adjectives. In this talk I will express power consumption and sustainable production in a single set of personal, human-friendly units. Getting off fossil fuels is not going to be easy, but it is possible.