I think it is important to understand that the term electricity can not be universaly applied. Current and charge are two different things that hasppen at the same time in a circuit. The flow of electrons is always in a closed loop, but the energy or charge is only one way. Meaning, the flow of electrons do indeed flow back to the source, but the energy that they deliver is distributed to the load in a different from such as light, heat, or motion. The picture above is a great representation of what looks like is happening, but in reality, the electrons are not charged back to the source.