In the internet of things context, the use of Wireless Sensor Networks (WSN) becomes extensive and the aspect of energy supply becomes more and more essential. Flexible positioning and easy maintenance become a key aspect for the acceptance of this technology. In this paper, we focus on novel trends for supplying WSN from ambient energy and by wireless energy transmission. The improvements made in the last years have shown that it is possible to significantly improve energy efficiency by suitable converters and to reduce energy consumption of sensor nodes, so that the use of these emerging technologies becomes increasingly realistic and practicable. We report about possibilities for improving energy income by combination of converters within hybrid solutions. Different techniques for enhancing efficiency of energy converters and reducing energy consumption on node and network level are described.