fuel cells, Apple and others are pursuing at least one other approach: solar augmentation. In a patent application dated April 24, 2008 and titled "Solar cells on portable devices" attributed to a number of Apple employees, Apple reveals possible plans to integrate solar cells into devices such as iPods and MacBooks. The application describes a scenario where, "Solar cells are typically stacked with other layers made of transparent or semi-transparent materials... Some of these layers may be used for display or input purposes, and some layers may be coated with various materials or they may be etched with product logos or other patterns." In other words, Apple is looking to cover the entire device, including the transparent display, with a layer of solar cells -- the latter approach already patented by Motorola. While the efficiency of solar cells and existing manufacturing techniques call into question the immediate viability of such an approach, it's intriguing nonetheless as a means to offset any lost battery life on the move to say, 3G.