Reiki energy is a subtle energy. It is different than electricity or chemical energy or other kinds of physical energy. Reiki energy comes from the Higher Power, which exists on a higher dimension than the physical world we are familiar with
When viewed clairvoyantly, Reiki energy appears to come down from above and to enter the top of the practitioners head after which if flows through the body and out the hands. It appears to flow this way because of our perspective. However, the true source of Reiki energy is within ourselves. This does not mean that we use our personal energy when we do Reiki, but that the energy is coming from a transcendental part of ourselves that is connected to an infinite supply of healing energy.