A system (10) and method for transferring energy utilises an evacuated recirculation duct (11), with a pump (20) to circulate gas and a control nozzle (22) to form a jet of gas. Hydrogen gas is provided into the duct to be circulated, and an electrical device (30, 32) provides energy into the jet of gas so as to form hydrogen atoms. A heat exchanger (44) is arranged downstream of the electrical device (30, 32), onto which the flowing jet of gas impacts. Means (40) are also provided to generate an electric or magnetic field in the region of the jet of gas between the electrical device (30, 32) and the heat exchanger (44), and is connected to a source (42) of electricity. For example an electromagnet coil (40) and may generate a magnetic field (B) transverse to the direction of travel of the jet of gas, or an electromagnet coil (40A, 40B) may generate a magnetic field parallel to the jet of gas.