The development of micro/nanosystems has increased the demand for integrating micropower modules. The demand of micropower has motivated researchers to work on energy harvesting (EH) and storage, in addition to selecting energy efficient devices that minimize energy consumption. Energy harvesters transduce environmental energy sources into usable electricity that powers devices. Depending on the types of energy sources, these harvesters can be classified mainly into three categories: mechanical energy harvesters, thermal energy harvesters, and radiation energy harvesters. The storage of electrical energy is based merely on electrostatic attraction‐repulsion mechanisms. Dielectric and electrochemical capacitors are capable to store electrical energy directly, that is, in the absence of any conversion process during storage mechanism. Galvanic cells are electrochemical devices that are capable to convert chemical energy into electricity. The selection of energy storage devices for power microscale system needs more analysis and one needs to be aware of the tradeoff between energy density, power density, and cycle life.