In This Town We Obey the Laws of Thermodynamics
On February 29, 2008, six members of Ottawa Skeptics converged on the Colonel By building at the University of Ottawa for a demonstration of the “Perepiteia Generator”, which internet rumours and media reports (but not the inventor himself) have been dubbing a Perpetual Motion Machine – a remarkable claim, and certainly within the mandate of a Skeptics organization to investigate. We were met there by the machine’s inventor, Thane Heins, who demonstrated his apparatus for us a couple of times, and discussed it with us for about an hour.
The generator and the “observations”
The apparatus (see Figure 1, below) consists of a small induction motor (cannibalized from a Ryobi bench grinder), on the shaft of which is mounted a wheel (the “rotor”). On the wheel are glued six rare-earth disc magnets. As the wheel spins the magnets pass close to the ends of several coils wound on steel cores. The rotor-and-coils assembly therefore constitute a simple electrical generator: pass a magnet near a coil of wire, and it induces a voltage in the coil.
Figure 1: Perepiteia Apparatus
The generator coils can be connected in various ways, from open circuit to dead short. Heins’ demonstration consists of running the motor with various electrical loads applied to the generator coils, from open circuit (no load) to dead short (maximum load). His claims about the generator center on an odd phenomenon: that when the coils are shorted, the motor speed increases, instead of decreasing as might be expected. However, this effect is only observed when there is a magnetic path from the generator rotor back into the motor (through the “wheel” assembly and the motor shaft). If a section of the steel driveshaft is replaced with a brass coupling (ie, a non-ferrous material) the effect disappears.
Heins interprets the motor speed-up as representing an increase in output power, for no increase in input power – a clear violation of the law of Conservation of Energy. His hypothesis seems to be that the magnetic field induced in the coils is coupled back into the rotor, and thence to the motor, feeding back energy in a self-reinforcing way.
Heins’ primary fallacy is in assuming that increased speed represents increased torque or power. While this seems intuitive, it is in fact wrong: torque does not necessarily increase with speed. Normally, an induction motor operates in a range where torque (blue curve on Figure 2, below) actually decreases with speed (ie. the grey area on Figure 2). This makes sense if you consider that increasing the mechanical drag on the output shaft will slow down the motor, thus the torque must be increased to prevent the motor from stalling. So the observed speed-up of the motor is simply irrelevant, without actual measurements of output torque. Once the motor’s torque curve is known, the output shaft power can be calculated as speed times torque (red curve in Figure 2). Heins’ academic host, Professor Habash of the U of O, has informed me by email that to date no such torque measurements have been attempted.
Complicating the analysis of Heins’ apparatus is the fact that he is not running his motor at full voltage and normal speed. Instead, he supplies it from a variac (a device for varying AC voltage), at a voltage well below the 120V that the motor is designed for. As a consequence, it runs at only a few hundred revolutions per minute, instead of the approximately 3500rpm one would normally expect to see from it. Running it at such a low speed causes it to overheat, which makes it impossible to run for long periods, and necessitates the use of a small fan to cool it after each run.
It should be noted that Heins is not the first to build a machine of this general design. In 1969, a New Zealand inventor Robert Adams developed a fairly similar-looking generator (though his was driven by a DC motor), which shows the same counter-intuitive speed-up behaviour under electrical load. Again, however, no actual increase of output power over input has ever been measured.
We began by asking Heins about the media reports that he is claiming to have invented a perpetual motion machine. We were somewhat encouraged at first when he assured us that the use of that term was an invention of the media, and he himself made no such claim. He then talked about being able to apply his invention to “regenerative acceleration” in electric cars. When asked for further information about this, he began by claiming that both braking and accelerating a vehicle consume energy, but with his machine he would be able to use the energy of acceleration to recharge batteries, as is presently done for braking. It soon became apparent that his definition of energy and energy consumption was somewhat different than those used in conventional engineering and physics.
Getting back to the description of the generator’s behaviour, Heins went on to explain that the observed behaviour was a violation of Lenz’s law, and by extension a violation of the law of Conservation of Energy (aka the 1st law of thermodynamics). He was apparently unaware that this is essentially the definition of a perpetual motion machine. When pressed on the issue of conservation of energy, Heins retreated into saying “That’s just my opinion, and I’m entitled to my opinion”.
3rd Party Analysis
In April 2007, Heins’ backers had the Perepiteia tested by a Kinectrics (formerly the Research Division of Ontario Hydro), a consulting lab in Toronto. The Kinectrics report concluded:
From the results of the test carried out at Kinectrics, although it was not possible to prove, the theory of back EMF may well have an effect in the magnetic loading effect on the motor generator arrangement as tested. Further tests should use a motor that can be driven at both the rated current and speed, so as to establish what the true effect the back EMF has on the generator output in direct comparison with the motor input conditions on both acceleration and deceleration of the motor.
Translated from engineerese, it says: “We think there’s something interesting going on in the magnetics of this thing, but running the motor in this odd way makes it too hard to study properly and get good results.”
Heins has protested the report, complaing among other things that some of the data tables give the wrong units (millivolts instead of volts). However, even when corrected, Heins’ calculations still show output power on the range of fractions of a watt, for several hundred watts being input to the motor. Not a promising start for a “free energy” device!
h1> When we met with Thane Heins in February, there had been a flurry of activity and media coverage. Heins had recently demonstrated his device to Markus Zahn (professor of electromagnetics at MIT), and Zahn had indicated that the observed effect was “interesting” and warranted further investigation. Riadh Habash, professor in the electrical engineering department at the University of Ottawa had provided Heins with lab space, and assigned 5 4th year engineering students to assist him. NASA had invited Heins to Florida to demonstrate his aparatus, and a patent application had been submitted.
Dr Habash was unavailable to accompany Heins on the NASA demo. Heins asked Dr Zahn if he was interested, and received the following response (which Heins posted at overunity.com):
It seems to me that before you give more high level demonstrations, that you need to do more homework on your induction motor speed up due to the presence of a strong permanent magnet. As I and others have stated, the effect is most likely due to the magnetic hysteresis of the iron material that gets shifted by the permanent magnet to a new DC operating point. If not already done I also think you need to do some careful performance measurements such as measuring shaft speed and terminal current magnitude and phase with and without the presence of the permanent magnet as a function of line voltage. You should also measure the magnetic hysteresis curve with and without a permanent magnet present of your simplest motor configuration that you demonstrated to me. This is not difficult to do. I attach a video entitled “Measurement of B-H Characteristic” that shows how this can be done with an oscilloscope, two resistors and a capacitor. It can also be done with an integrating op-amp circuit. The attached text materials from the book by Haus and Melcher entitled Electromagnetic Fields and Energy also describe the measurement method and theory. In any measurements you should also measure the true electrical power in from your outlet power (voltage, current, and phase angle) as well as shaft power (torque and speed).
Any talk of perpetual motion, over unity efficiency, etc. discredits you, now me, and your ideas. I would not want to go to NASA or anywhere else to help promote your invention until basic testing and measurements are done so that the cause of shaft speed up due to a permanent magnet is understood and that the foolishness is stopped of hinting that your motor violates fundamental laws of physics.
Best of luck to you,
Commenting (on overunity.com) about the status of the student’s work, Heins wrote (in all caps, as appears to be his custom on that forum):
I DID NOT INSIST THAT THEY HELP ME BECAUSE I DIDN’T WANT TO INTERFERE WITH THEIR SCHOOL WORK.
I have been able to find no reports about the trip to NASA, so either it is highly classified or did not happen.
Most disturbing of all, however, is the fact that there has still been no measurement of the behaviour of the apparatus under physical load – Heins continues to extrapolate from the speed and acceleration characteristics.
Heins appears earnest and basically honest, but persistently self-deluded. While some of the phenomena Heins demonstrates may be interesting, the evidence of a real and measurable effect appears to be lacking. Heins claims that the behaviour of his apparatus is contrary to what is predicted by known physics, yet he applies standard physics calculations to demonstrate his point. He sets up the motor to operate under extreme conditions, but applies analysis used for normal operation. He does not seem to understand the importance of demonstrating the response of the apparatus to an actual physical load, despite the fact that many people (including those who at one point were sympathetic to his project, but now have doubts) have recommended he do this, and even provided instructions. While the speed-up behaviour of the generator currently lacks an established explanation, there is no reason to think that it represents any challenge to currently known laws of physics.
Copy of the patent application.
Wikipedia article on the Perepeteia machine, includes links to some debunking articles.
Information about the Adams motor can be found here.
More than you care to know about perpetual motion machines is at the Over Unity forums (“overunity” – when the energy output of a device exceeds the input)