Energy supply considerations for self-sustaining wireless sensor networks

The challenges of designing a power supply including generation, storage and conversion are manifold and design problems are difficult to solve with off-the-shelf hardware components. One has to think about losses all the time when overall leakage currents of less than a few microamperes are desired. In general, reducing the complexity of the circuit reduces the power consumption as well, but efficient charging of an energy storage element such as a battery or ultracapacitor becomes difficult. Finding a well-balanced point where sum of leakage current and charging losses reaches a minimum is the way to go. This paper discusses this issues and shows some diagrams and solutions to the power supply problem one is confronted with, when designing energy self-sufficient sensor nodes.