Nanotechnology, the structuring of matter at near-molecular scales, offers the prospect of solving all these problems at a stroke. Non-thermal use of energy, in broad emulation of what organisms do already, will not only lead to more efficient use but make practical diffuse sources such as sunlight. Pollution control and resource extraction become two aspects of the same fundamental problem, the low-energy extraction of particular substances from an arbitrary background of other substances, and this also is in emulation of what biosystems carry out already. This book sketches out approaches both for the efficient, non-thermal use of energy and the molecular extraction of solutes, primarily from aqueous solution, for purification, pollution control, and resource extraction. Some long-term implications for resource demand are also noted. In particular, defect-free fabrication at the molecular level is ultimately likely to make structural metals obsolete.