Powertop

PowerTOP is a software utility designed to measure, explain and minimize a computers power consumption. It works for both Intel and AMD processors. It analyses the programs, devices and kernel options running Linux or Solaris. It estimates the power consumption for any computer.

This information can be used to find out what programs / devices are using excessive power. The focus of powertop is monitoring CPU sleep states, and showing the programs or drivers responsible for “wakeups” which prevent CPUs entering sleep states. A database of known quick fixes have been added to decrease power consumption.
PowerTOP uses this feature to estimate power usage in Watts and battery life.