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NEWSCIENCENEWSCIENCENEWSCIENCE we were to shake this device up and down, causing the balls to bounce between the plates, electrons would be transported from plate A to plate B. These electrons could be allowed to return through an external circuit and do work. We can regard this device as an electrostatic generator. verter to operate as intended. The main function of the insulator is to reduce the electric force holding the charged ball to the plate. Heat energy does not kick just the balls around, it also kicks electrons around. As a consequence of the thermal activation of electrons, the charge on the balls may be neutralised or even reversed. When the polarity of electric charges is reversed, we have an internal leakage cur- rent which can reduce or even stop the cur- rent in the external circuit. Fortunately, careful calculation shows that under certain conditions the cell can generate power. If the cell generated any power at all, however little, it would mean that the sec- ond law is not a universal law after all, and that there probably exist other methods which also work and are of practical value. Fortunately, the thermal converter can gen- erate enough power to be of very great practical interest. With development, it can only get better. One such improvement is the suppres- sion or elimination of the internal leakage current. Figure 3 shows a version of the converter in which the layers of insulating material are replaced with semiconductor material which can still perform the insula- tor's function. Plate A is coated with n- type semiconductor, and the balls can get electrons readily enough but can give up electrons only with great difficulty. The p- type semiconductor on plate B acts in reverse, and the cell now behaves like a diode with respect to the balls. Please note that the original analysis takes full account of the thermal activation of charges, and the claim that the converter works does not rely on this diode action. Other improvements relate to the mass of the balls. By using hollow shells, their mass can be greatly reduced (we cannot make them smaller), which increases their speed and hence power output. The power of this device increases rapidly if the tem- perature at which heat is available is raised. Elevated temperature allows us to reduce the size and mass of the balls, and hence a larger number of balls per unit area move between more closely spaced plates at greater speed. THERMAL CONVERTER The electrostatic generator can become a thermal converter if we cause heat to do the shaking about of the balls. Heat energy is constantly trying to shake the balls. The energy available for this is proportional to the absolute temperature, T, and is calculat- ed with the constant, k (Boltzmann's con- stant). When the balls are small enough, their agitation by heat energy fluctuations can make them bounce back and forth between the plates. At a diameter of 10 nm, the thermal activation of the balls is sufficient, and we have the possibility of a thermal converter producing a spontaneous flow of current as long as the temperature is maintained. A possible thermal converter operating at ambient temperature is shown in figure 2. It differs from figure 1 in that its scale is now defined and the plates are coated with a thin layer of insulating material. One would think that this insulator would stop the electric charging process, but if the layer is thin enough then electrons can 'tun- nel' through often enough to allow the con- POTENTIAL APPLICATION OF THE THERMAL CONVERTER A typical thermal converter would look like a stack of plates with air spaces between them. Air or water is drawn between the plates, keeping them warm. The power output is about one kW per kg of mass, and the average density is about 500 kg per cubic metre. This makes the converter powerful for its weight, and com- pact. For example, a 100 kW unit suitable for powering a car would have a weight of 100 kg and a volume of 0.2 cubic metres. The operation of the device is silent and vibration-free. The converter could be used for both small- and large-scale ower generation. If the electric ower produced is expended in the locality of the converter, the environmental impact is very minimal because heat is taken from and returned to the envi- ronment at the same time. If the energy is exported to other laces, as for example by elec- tric transmission, then the envi- ronment of the converter is TOR cooled. It would be immediately use- ful in motor vehicles, ships, and industrial and domestic applica- tions. For use in powering air- craft, a ratio of 10 kW per kg is desirable, and this application would need to await further development of the converter. The converter is an intricate device requiring a high level of technology. A thousand cells might stack up to a thickness of —+—++ 10 nm PLATE - B PLATE -A 52 - NEXUS JUNE - JULY 1998