A system is disclosed for converting energy from the electromagnetic quantum vacuum available at any point in the universe to usable energy in the form of heat, electricity, mechanical energy or other forms of power. By suppressing electromagnetic quantum vacuum energy at appropriate frequencies a change may be effected in the electron energy levels of atoms which will result in the emission or release of energy. Mode suppression of electromagnetic quantum vacuum radiation is known to take place in Casimir cavities. A Casimir cavity refers to any region in which electromagnetic modes are suppressed or restricted. When atoms enter into suitable micro Casimir cavities a decrease in the orbital energies of electrons in atoms will thus occur. Such energy will be captured in the claimed devices. Upon emergence form such micro Casimir cavities the atoms will be re-energized by the ambient electromagnetic quantum vacuum. In this way energy is extracted locally and replenished globally from and by the electromagnetic quantum vacuum. This process may be repeated an unlimited number of times. This process is also consistent with the conservation of energy in that all usable energy does come at the expense of the energy content of the electromagnetic quantum vacuum. Similar effects may be produced by acting upon molecular bonds. Devices are described in which gas is recycled through a multiplicity of Casimir cavities. The disclosed devices are scalable in size and energy output for applications ranging from replacements for small batteries to power plant-sized generators of electricity.