Currently, the predominant technologies for autonomous portable power supply are batteries. Alternatives in the range 0.1-10 W are explored in this work, focusing on the combination of fuel processing with fuel cells. A methodology for the comparison of different alternatives for micropower generation processes based on a process superstructure, including hundreds of different designs, is formulated, and the first implementations of system simulation are presented. A comparison between a variety of processes under different constraints is presented, and the influence of heat losses, scale, fuel cell efficiency, and conversion as well as recycling on the performance of the processes is discussed. Conditions under which the technologies considered are a promising alternative to batteries are identified.