We Tweet, Facebook, Netflix and YouTube in the palm of our hand. We are aware of the amount of energy that it takes from how many times that we need to recharge our devices. However, this is just the tip of the iceberg. For every joule of energy we expend locally, many more joules are spent in the backbone of the Internet. While our appetite for data has largely been insatiable over the last thirty years, the energy required to sustain this has been held in check by Moore’s Law’s driving creed that density of function in a computer chip increases by two every two years, and energy/function decreases by a similar amount. With that said, this driving relationship between power consumption and computing density is slowing due to a multitude of physical constraints when the density of transistor packing approaches the limits. In the following chapter, the authors examine these relationships and outline some of the challenges that the world is facing as we continue to meet and exceed the expectations of our data-driven world with a finite growth in worldwide power generation capacity.