Everything has its own energy. Everything has its own source. So your aura is your own energy, and depending on the color, it shows you what you're currently being affected by. You are your own source of energy.
You can do things to cleanse your energy and make yourself feel newly cleansed and fresh. The simpest thing is to take a bath or a shower. Sometimes people add certain things to their baths to relax them more. Like lavender, or eucalyptus. Meditating or chakra cleansing (if you're into that) is another good way to cleanse yourself. Simply running sage smoke over yourself while visualizing bad energy flowing out of your body is another good technique.
But, there is no one flowing source of power, or energy. Everything has energy and everyone has it.