Use Granola to Monitor and Save Energy Costs on Computers

Granola is a software designed to save money on running and operating a computer whether it be a laptop or desktop. The free version is available for download at grano.la.
 How it works taken from grano.la :

Basically, it's a dimmer switch for your computer's processor. When you're doing your taxes or writing a letter you want bright light to see what's going on and get done as fast as possible. When you've finished working you can relax, pop open a bottle of wine, and dim the lights again because your productivity needs have changed.
That's how this works. Granola uses fancy algorithms to model your power needs and "brighten" or "dim" your CPU automatically. You could actually do this yourself if you wanted to – but Granola can do it hundreds of times per second, and that's where the free lunch comes into play.

Because Granola can respond so quickly, you can have top speed as soon as you need it and drop back to maximum savings as soon as you're done with your task – or even in the few seconds the CPU is waiting on your disk drive or internet connection. In fact, Granola is so fast that you will save energy without ever seeing a drop in performance.