Re: How do you store electrical energy from the source?
Your first example , the rod and fur, produces static electricity which transfers at a sudden rate rather the a slow charging rate. Such a charge can be stored in a capacitor, or in the fur until it is transfered. Batteries are not made to take this type of high voltage low current sudden jolt.
For mechanical means I'm guessing you mean a generator or alternator. A generator produces DC voltage that can be applied directly to a battery or capacitor to charge the battery or capacitor. An alternator produces AC voltage which can be converted to DC with the use of a bridge rectifier and then applied to a battery or capacitor.
Be sure you live your life, because you are a long time dead.-Scottish Proverb