How important is energy efficiency in relation to what you wish to achieve domestically and internationally?

Energy Efficiency is about using less and less energy to produce the same amount of useful work. 

In mathematical language,  it is the ratio of "useful energy" in producing the desired effect divided by the "total energy" supplied to get the job done.

Let me quote2 examples

1. Ellectic enegry supplied to an electric lamp to produce light  will be of2 parts;  "useful" energy used in producing the iight and "wasted" energy in the form of heat generated in the lamp
2. Fuel (chemcial energy) supplied to a car engine will produce motion (desired and useful form of energy .. and lots of heat due to internal metal metal friction between moving parts.

Think of energy efficiency in terms of inventions or tools that will increase the useful part and reduce the "wasted" part  of the energy supplied to produce the desired effect; car jack, hydtaulic jacks,LED lights, lubrication oils, ... etc .. etc.