While computing, display, communications, and storage technology may become efficient enough to require unobtrusive power supplies, the desire for the fastest CPU speeds and highest bandwidth possible will offset the trend. In addition, dependence on power cells requires the user to ``plug in'' occasionally. This is impossible in some military and professional contexts. If body motion is used, it may be significantly more convenient to shift weight from one foot to another, for example, than to search for an electrical outlet.
Each of the generation methods has its own strengths and weaknesses depending on the application. However, power generation through walking seems best suited for general purpose computing. The user can easily generate power when needed, and, in many cases, the user's every day walking may be sufficient. A surprising amount of power (5-8 W) may be recovered while walking at a brisk pace, possibly without stressing the user. If less power is needed, piezoelectric inserts may be used reducing the mechanical complexity of the generation system. However, issues of energy storage and human factors still have to be resolved. Thus, the natural next step is to prototype a generator.