How can I increase battery life in Ubuntu?

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http://askubuntu.com – I really like Ubuntu, and I want to work with it always instead of windows. But the problem I find is that the battery runs out very fast (< 2 hours) when I use Ubuntu. It would have been great if I could get like 3 - 4 hours of battery life. My windows provides me 4.5 - 5 hours. Is there any way to increase battery backup? I have tried to disable my AMD Radeon graphics by adding radeon to blacklist. But still there is a lot of heating. My laptop is a Compaq Presario CQ43. And I'm running Ubuntu Studio 12.04. (HowTos)