How do you reduce the Power dissipation?

Answer for mechanical systems:

Use oil or grease to reduce friction!

Answer for electrical systems:

Making the voltage as high as possible is a good way to reduce power loss.

Explanation

The voltage drop along a conductor is proportional to the resistance and to the current carried. (V=IxR) So, for a given quantity of Power (W=VxI), if the voltage is made as high as possible there will be less current flowing and therefore less power loss.