Converting ambient energy into electrical energy to power wireless autonomous devices instead of batteries opens up a variety of opportunities to design electronic systems that last a life time, and don't ever need maintenance. This talk discusses the state of the art in energy harvesting, focusing on light, heat, and vibrations, and elaborating new storage media such as solid state cells and super capacitors. The emphasis is on practical applications and examples rather than theory, aiming to guide the audience on the way to removing batteries from their own creations and replacing them by energy harvesters.