Ubuntu's Power Consumption Tested @ Phoronix
 

For this article we've decided to not only deliver power benchmarks from Ubuntu 7.10 and Ubuntu 7.04 to compare the tickless kernel effect, but we have went back and retested all of the Ubuntu releases going back to Ubuntu 5.04, or also known as Hoary Hedgehog. With the past six Ubuntu releases we had tested the power consumption of a Lenovo laptop when running from its AC charger and off the battery, when the system was idling and then again under load. We had also monitored the temperature of the Intel Centrino mobile processor. You may be surprised by the results of Ubuntu's power usage.