A thermoelectric generator is a device which produces electricity from a change in temperature. These things can be expensive and difficult to make, not least because they often use toxic materials. Now a team of researchers at the Fraunhofer Institute for Material and Beam Technology in Dresden are demonstrating at the Hanover Trade Fair a way to produce miniature thermoelectric generators with a 3D printer. See here. These tiny generators can be printed on flexible materials using non-hazardous synthetic substances. Possible uses include generating electricity from the waste heat in steam at generating plants and from the exhaust pipe of cars.