Scientific illiteracy is alive and well in Philadelphia! On Sunday, September 15, the Philadelphia Inquirer carried a full page advertisement announcing 'America's Declaration of Energy Independence.' The ad promised a demonstration of a heat system which would generate free electricity from the air, a car engine which would run on water and a number of other counterintuitive devices. While this might or might not be too good to be true it was obviously too good to turn down so I and some fellow skeptics found ourselves amongst the audience of some 3000 in the Core States Center on a Monday night a week later, prepared, to quote the ad, 'to be amazed ... even shocked.'
The event was sponsored by Better World Technology (which is unrelated to the Better World Society). This turned out to be one of those uniquely American organizations based on a blend of populism, perversity and paranoia. The format was a monolog by one Dennis Lee, former heat pump salesman turned free energy promoter. This was interrupted by demonstrations of the various devices set up across the arena, by tape clips, by effusive praise of neglected inventors, by appeals to patriotism, and by denunciation of the energy utilities, the Federal Government and the Department of Energy who harrass selfless innovators. The show continued before a mostly rapturous audience from 7.30 until well after midnight. Your dedicated PhACT investigators stayed until things started winding down, leaving a little early in case the parking lot got bogged down with stalled water-powered cars.
It is difficult to do justice to an event like this; there was so much going on and yet so little of substance behind it. Marvel after marvel was demonstrated but, impressive as things seemed to the lay audience, nothing happened which appeared out of the ordinary to anyone with the least grasp of physics or engineering. Mr. Lee seems to have been overly impressed by the fact that the thermal output of his heat pumps is six times the electrical power used to drive the compressor. A volunteer from the audience confirmed that one pipe got hot even though the input was at room temperature. Although heat pumps have been around for at least thirty years, the spectators were impressed. The reasoning then went: If the heat pump puts out six times as much energy as it takes in, let's use some of its output to generate the power needed to drive the compressor. This would take, perhaps, two units. However, this still leaves two units to power all the lights and appliances in your house and even leaves two units to sell back to the utility company. The only problem, Mr. Lee thought, was that his researchers hadn't yet come up with a 50% efficient generator which would run from the heat pump.
Since the heat pump output is too cool to boil water this generator will use a 'low temperature phase change,' that is, it will use a low boiling point liquid. This will be introduced into a cylinder, will boil, pushing the piston, and will then, conveniently, condense back to a liquid, ready to be warmed up and reintroduced into the cylinder for the next stroke. This is not a new idea. In 1881 John Gamgee called it the 'zeromotor' and tried to sell it to the US Navy. It was going to power their ships by using the sea water to boil ammonia. Even President Garfield thought it was a good idea.
Unfortunately, all heat engines need both a source of heat energy and a lower temperature sink to cool or condense the working fluid. Even under ideal conditions the output of mechanical energy is always less than the input of thermal energy. The maximum efficiency is a function of the input and output temperatures and cannot be improved by a clever choice of working fluid. If these temperatures differ only slightly an engine will produce only a tiny amount of mechanical energy even though a huge amount of heat flows through it. Normal power stations are about 60% efficient note by Eric -some say this is 35% Tom has since verified the number in an issue of Scientific American., 40% of the heat from the burning oil or coal goes into the cooling towers.
A heat pump reverses the process. A small amount of mechanical energy, from the electric motor which turns the compressor, pumps heat 'uphill' from the cold air outside the house to the warm air inside it. This generates more heat than a convector heater driven from the same power. A heat pump is most efficient when the difference in temperature between the input and output is small. In fact, the equation which determines the heat output of a heat pump is the reciprocal of the equation which determines the efficiency of an engine working between the same two temperatures. If you had a perfectly efficient heat pump and a perfectly efficient generator the electrical power out would exactly match the electrical power in, no matter what temperature the system was running at. Of course in real life the power out is always less than the power in -- so much for selling your excess power to PECO Energy.
This is the fallacy behind 'free energy.' The other theme which characterized the demonstrations was a misunderstanding of the difference between force and energy. Energy is only generated when a force acts through a distance. One demonstration showed an engine generating a large torque (rotational force) while hardly moving. Since this torque was larger than the manufacturer's specifications, it was taken to indicate enormous power output. It would have done if the engine had been turning at 3000 rpm but it represented negligible power when the engine was almost stationary. One demonstration used low pressure Freon to generate high pressure hydraulic fluid which then turned a wheel rather slowly. The only thing extraordinary about this was the claim that the torque was high enough to drive a tractor-trailer. Undoubtedly it was but only at a few inches a minute. The demonstration amounted to saying that because a man could lift a heavy rock with a crowbar he could also make it fly hundreds of feet in the air.
No presentation of this nature would be complete without the engine which runs on water. No one disputes that an oxygen-hydrogen mixture can drive an engine and produce water. No one disputes that this water can then be split into oxygen and hydrogen. Unfortunately the energy needed to split the water is greater than the energy generated by the engine. The fact that the oxygen-hydrogen mixture was being supplied by four commercial welding gas generators was not emphasized; neither were the heavy cables running off-stage which were powering the generators. Alas for 'free energy,' the show must have had a substantial electric bill.
I could relate more marvels: the taped infomercial for a fertilizer which comes with a cassette tape to play to your plants, the personal appearance of Yull Brown, the greatest inventor who ever lived (Apart from Nikola Tesla, of course.) who had given us 'Brown's Gas' to run our cars, the device, thankfully not demonstrated, which would render nuclear waste harmless, the two-page fine-print parody of the Declaration of Independence which the audience was invited to sign. But one sad device typified the entire show.
Despite studying pseudoscience for some twenty-five years I had never before been privileged to see a demonstration of a real perpetual motion machine. That Monday night the inventor of the 'Gravitic Torque Amplifier' demonstrated how, by using a 'perpetual inclined plane,' one could generate power from a large inclined disk rolling in a circle. He spun this device up with an electric motor, measured its torque, then, rather than leave it running for the rest of the evening, perhaps braking it if it spun too fast, he stopped it. I was disappointed, I had so wanted to watch it grind to a halt. The beauty of alternative technology, unlike some other 'alternatives,' is that you can be sure it won't work.
It was not immediately obvious how this extravaganza was being paid for. Further research has revealed that dealerships to distribute this technology have been sold for $10,000 apiece. Donations are also solicited with the condition that no return is guaranteed and that no information about the technology will be revealed other than these public demonstrations. An audience member told us that 2000 dealerships had been sold. That's $20 million, enough to pay for quite a few shows and newspaper ads. The promoters may well believe, as they claimed, that they are within months of demonstrating complete, working 'free energy' units and of liberating the people of America from the oppression of the power companies. Whether you call this a scam depends on your point of view. I think it shows that an ounce of science is worth a ton of razzmatazz.
Broadcasting my article on Dennis Lee's Philadelphia demonstration (A Glimpse of Cloud-cuckoo-land, Phactum, October 1996) into cyberspace seems to have raised hackles amongst free energy proponents. Three criticisms have been levelled. One is that I say that heat pumps don't work. One is that everything which I say must be wrong because I mentioned in passing that power stations are 60% efficient. Then I am criticized for not mentioning all of Lee's other wonderful devices such as the silent jack-hammer. Let me be quite clear. Heat pumps do work and I have never said that they don't. I have some practical experience in the matter since for eleven years I have been living in a house which is heated by one. (Not supplied by Mr Lee, I hasten to add. Mr Lee's heat pumps incorporated a solar collector. They may have worked better than most on a clear sunny day but would, I guess, work somewhat worse on a clear night. However this is not a vital point.) A heat pump takes heat energy from the outside air and adds sufficient energy, in the form of the electricity driving the compressor, to raise the temperature of the working fluid from the outside temperature to above the room temperature. Its heat output is equal to the heat input from the outside air plus the electrical energy input, minus conversion losses and the power needed to drive the blowers. One calculates a heat pump's Coefficient of Performance (CoP) as (Heat Output)/(Electrical Input). Since most of the heat supplied is coming from the outside air, the CoP is higher than one. However, this is just arithmetic, not magic. By comparison, the CoP of a convector heater is exactly one, which is why people install heat pumps. The maximum possible CoP of a heat pump is easily calculated from the inside and outside temperatures. [In Fahrenheit degrees, CoP = (Ti+460)/(Ti-To)] The lower the outside temperature, the more energy has to be made up by the electrical input and the lower the CoP becomes. Eventually it becomes pointless to run the heat pump at all. When the outside temperature drops somewhat below freezing, I turn off my heat pump and start my coal furnace. What I have said is that the part of the "free energy" loop which Lee has not demonstrated, and which he can never demonstrate, is the engine which turns the heat pump output back into more electricity than is driving the heat pump. It is totally impossible for any engine using any technology to take the output of a heat pump and to return more electrical energy than was put into the heat pump in the first place. The proof of this is very simple, the efficiency of the ideal theoretical engine is exactly equal to the reciprocal of the CoP of the ideal heat pump. Heat pump theoretical CoP times engine theoretical efficiency equals unity. If anyone could demonstrate such a system with an electrical output of even as much as 90% of the electrical input, I would be very surprised. As for free energy, there is none. There are no loopholes in the second law of thermodynamics . Point the second. As has happened before, in the interests of brevity I have left myself open to misinterpretation. The thermodynamic efficiency of a typical power station is, as I said, about 60%. This is easily calculated from the input steam temperature and the output cooling water temperature. This means indeed that the waste heat is 40% of the input. If one takes into account practical considerations such as the efficiencies of real turbines and alternators, the absence of cogeneration and the presence of scrubbers, the electrical output of a real power station is in the region of 37 to 41% of the thermal input. Doubters can check the detailed analysis on page 151 of the September 1971, Scientific American. I used the 60% figure since, when discussing heat engines and free energy devices, I have been referring throughout to maximum theoretical performances. This is to avoid anyone claiming that their machine is much better than any "typical" figures I might quote. As for the many other strange devices which Dennis Lee was promoting, who cares? He is promising endless free energy. If he can achieve that then noise-free jack-hammers are rather small potatoes. It's as if someone came to you and offered you eternal life and a 10% discount on your phone bills. Let's see that free energy machine working first. And, just for the record, my allusion to "scientific illiteracy" referred to the cheering audience, not to the presenter, about whose credentials, and past, I then knew nothing.
Tom Napier
Since the early nineteenth century it has been known that the amount of heat energy in something, a gas, a liquid or a solid, is proportional to its temperature, measured on the Kelvin scale. (Zero Kelvin is -273.2 C or -459.8 F) A liquid at the boiling point of water, 373 K, which cools to the freezing point of water, 272 K, still contains 73% (273/373)of its original heat energy. The 27% difference represents how much of its original heat energy was extracted as the liquid cooled.
In principle, an engine with its input maintained at boiling point and its output maintained at freezing point could convert all of this 27% of the input heat energy into useful mechanical energy. The remaining 73% of the input energy is carried away by the cold output and can't be used. No engine running between these two temperatures can, even in theory, convert more than 27% of the input energy into output energy. Of course, any real engine will have a useful output of even less than 27%.
To get an electrical output, one drives a generator with the mechanical output of the heat engine. Luckily generators are quite efficient so almost all of the available mechanical energy can be turned into electrical energy.
The ideal heat engine is reversible, that is, if mechanical energy is put into it, it will output heat energy. A heat pump uses mechanical energy to move heat from a low temperature input to a high temperature output. The output heat energy is equal to the input heat energy plus the input mechanical energy. A heat pump running between the freezing and boiling points of water has an output of 100% for a mechanical input of only 27%. Thus the heat energy output is 3.7 times the mechanical energy input. 73% of the output energy is coming from the cold input.
Using more typical figures, say 40 F for the outside air and 70 F for the room temperature, 94.3% of the heat supplied to the room comes from the outside air. Only 5.7% needs to be supplied by the mechanical energy input. Thus the heat energy supplied is more than seventeen times the mechanical energy put in. In a real heat pump the mechanical energy comes from an electric motor; the heat output would be, perhaps, twelve times the electrical input.
If the same electrical energy were used to generate heat directly, for example, in a convector heater, the heat energy put out would equal the electrical energy put in. Thus a heat pump is a much more efficient way of generating heat than is a convector heater. However, this only means that convector heaters are not the most efficient way of heating your house, not that a heat pump is 1200% efficient.
Suppose, as has been proposed by free energy advocates, we use the heat pump's output to drive a heat engine and a generator. The engine's hot input would be at 70 F and its cold output would be the 40 F outside air. Under ideal conditions, the efficiency of the conversion back to electricity will be 5.7%. That is, the generator will supply exactly as much energy as we put into the heat pump in the first place.
This relationship applies whatever temperatures we chose as input and output. What you gain in the heat pump, you lose in the generator. In any real device the energy out will be less than the energy in and the overall efficiency will, sadly, be well under unity.
Tom
Napier's Oct 30th update on Dennis Lee:
About a year ago Lee came up with another idea. He
would
drive an engine from a tank of liquid carbon dioxide. In some
unspecified way the exhaust carbon dioxide from the motor would
be induced to return to the high pressure tank. This wasn't even
an original idea, it had failed when John Gamgee had tried it
back in 1881. The experts said this couldn't work and sure
enough it didn't. Strike Two.
Go to Lee's travelling circus in November 1999 and what
do you
see? An over-unity electric motor; now where did he come up with
that idea? His latest gadget is an electric motor whose body
is
able to rotate. This is supposed to supply twice as much torque
as a normal motor whose body is fixed.
Lee must be terribly confused about the difference between
torque and power. Something which exerts torque only generates
power when it is allowed to move. A static torque supplies no
power. Still, it looks as if allowing the motor body to rotate
supplies extra power. Well you need to look at things from the
motor's point of view. If its shaft is braked, as it is to
measure the torque, then allowing the motor body to rotate
increases the relative speed of the armature and the stator.
This makes the motor more efficient, just as Lee says. What he
doesn't say is that you could achieve the same result by reducing
the braking without allowing the body to rotate. Or, if you want
more torque, just add a gearbox.
DC motors achieve high efficiency (80-90%) only when rotating
at, typically 3000 rpm. If you apply a brake, the motor torque
increases, the speed decreases and the current drain increases.
Since the input power is current times voltage, it has increased.
The output power is torque times rotation rate and it falls
somewhat as the speed decreases. The net result is that at low
speeds the efficiency of the motor is very low. Anything which
allows the motor to run faster will increase its efficiency.
However, if you "double the efficiency" you haven't gone from 80%
to 160%. You have gone from 10% to 20%. How do we know
this?
Lee himself gave us the numbers at his first show of the
1999
tour. Initially his motor was running at 219 rpm with an output
of 6 inch.pounds of torque. That's a power output of 15.5 watts.
Its input was 15.5 amps at 13 volts. That is a power input of
201.5 watts for an efficiency of 7.7%.
When the motor body was rotating the speed increased to
438
rpm at a torque of 7.5 inch.pounds. That's 38.8 watts of output.
The input power fell to 12 amps at 14 volts or 168 watts. That
means that the motor was now operating at a breathtaking 240% of
its original efficiency. Its efficiency had risen to all of
18.5%. Yes it improved but it is still well below normal and
a
long way from "over-unity." Strike Three.
Tom Napier
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happy to publish critical responses to my claims.