The creation of the digitaf world is perhaps the most remarkable engineering event of the late twentieth century and may be compared in impact to the harnessing of steam at the beginning of the nineteenth. Obviously, the rwo cannot otherwise be compared, representing as they do the transition from the era of power to that ofinformation. Even the term transition is misleading because the digital world depends entirely on the prior existence of sources of electrical energy, currently derived largely from thermal and nuclear processes, with an ever-increasing reliance on renewable content including the harnessing of tidal, wind and solar sources. Furthermore, chemical sources ofenergy should not be forgotten, including the wide range of personal batteries powering everything from laptop computers to hearing aids and pacemakers, and the currently-developing fuel-cell technology that may yet make the electric automobile a viable proposition.