Broken link.

I'm not a fan of those for long term use I have heard too many stories of them wearing out, shorting, and starting fires. Plus, since you are using another device that is changing electricity you are going to actually raise your power bill by using it.

To quote Homer Simpson "In this house we obey the laws of thermodynamics."

Any time you use a device to change energy the the 2nd law of thermodynamics says you are going to lose energy, thus you will use more to power the same system.