Hm.

That's my first reaction to the Entropy Engine, an engine which its inventor claims runs on no fuel, requires only maintenance, and barring the inevitable wear and tear could conceivably run forever.

Here's the story, and why I'm deeply skeptical of it interspersed with it.

The Little Engine that Might
by Leander Kahney

Taking on the world's giant energy business, a tiny startup is set to launch an engine that requires no fuel, produces no pollution, and is free to run.

This is one of the first disturbing signs. If there really *were* an engine that required no fuel, produced no pollution, and is free to run, there would be a huge buzz about it. HUGE. "Oh, it would just get suppressed by the megaindustrial petroleum complex," you might say, catering to your favorite conspiracy theory, but lemme tell you, the megaindustrial petroleum complex has NOTHING on how much the military would love this. You think it's *easy* carting fuel to tanks, which generally get about a mile per gallon on the flat? *Gad*, the military would happily *give* me a dozen F-16s for this sort of technology. So would Greenpeace. So would . . . well, pretty much everybody.

Naturally, the experts think it's too good to be true -- although they can't exactly say why.

The second disturbing sign. Why not actually put the science up for testing? Why spend a lot of time theorizing? The second law of thermodynamics tends to already cover machines like this.

The Entropy engine acts like a heat sponge, absorbing heat in the atmosphere and converting it to power, Amin said. Since it consumes no fossil fuels, nuclear fuels, or electrical power, it produces no emissions, directly or indirectly. Its only byproduct is cold air.

Oh. So it's a heat-differential engine. Nothing new about that. Heat-pump engines operate via heat-exchange---when you have a heat differential between one thing and another, that heat energy wants to transfer and create equilibrium. You can use that transference to drive something. These come in several forms, but always require a differential in order to work.

Initially, the technology will be used to create an outboard motor for small pleasure boats, simply because it's the easiest market to break into, Amin said. But as it is developed, the technology could be used to run refrigerators, air conditioners, generators -- even automobiles.

Er . . . well, the outboard motor version makes sense, because by immersing part of the engine in cold water, and leaving part of it in warm air, you're going to wind up with a heat differential, which can drive a propeller. Of course, it's not going to be a very powerful engine---the heat differential isn't that huge---but yeah, it'll drive a small pleasure boat. Slowly.

"There's no reason it can't power a car," Amin said.

I *do* have a problem with this. Where is the heat differential going to come from? I suppose you could generate a mild one if you had a big metal probe lodged up your butt---on cold days, your butt would be able to generate enough power to drive a really teeny car a few miles an hour, and if you could harness the energy in the buttock-clench efficiently, you might add another mile an hour at most. But on warm days, while the probe would be a lot more comfortable, you'd barely be moving at all. And on days where the outside temperature was in excess of 98.6F, you wouldn't move in the slightest.

So far, Amin has built a prototype, which he said generates one-tenth of one horsepower. The outboard motor -- yet to be built -- will produce between two and three horsepower.

I completely scoff. 0.1HP is pretty good for a heat-differential engine; 2HP requires a much larger differential. You might be able to get that if the prop were extended down in the water several hundred feet, where the temperature is near-freezing (depending on the body of water).

It will be roughly the same size as a conventional outboard motor and only marginally more expensive. But, apart from routine maintenance and lubrication, the engine will be free to run.

Named after the unit in physics that describes the amount of available energy in a system, the Entropy engine consists of a central chamber, filled with air, that has a piston in the center, Amin said.

The engine operates on a cycle. First, a starter motor spins the engine to a high speed, which pushes the gas to the edge of the central chamber, as in a centrifuge. As the gas moves to the edge, it creates a partial vacuum in the center that draws the piston out, compressing the gas.

In the second part of the cycle, the engine is slowed, and the gas redistributes itself throughout the chamber, which increases the pressure on the piston. Heat trapped in the gas is converted into the energy that moves the piston, which cools the air in the engine chamber.

Curiouser and curiouser. If it runs on no fuel, WHAT DOES THE STARTER MOTOR REQUIRE? This has to require a very light cylinder to get pushed in and out with a mild vacuum.

The engine will run year-round in any climate, even in sub-zero temperatures. Although it operates better in warmer climates, it will work in any environment above absolute zero (minus 273 degrees Celsius).

*bzzt* Fatal flaw. It can only work if there's a sufficient heat differential. And remember, it's not *entirely* fuel-free.

"In physical terms, even ice has a lot of heat," Amin said.

Compared to a Bose-Einstein condensate, yes. But for most practical considerations, no.

Amin claims to have patented the technology in the United States, Australia, and Europe. He said he has published a book on thermodynamics and in 1996 received an Engineer of the Year award from the American Society of Engineers of Indian Origin.

And I've never heard of either the organization, or his book.

Always obsessed with engines, Amin built steam engines as a teenager. He has devoted more than a decade to the Entropy engine. He began by looking at gravity as a power source, which eventually led to the idea of using atmospheric heat.

Lots of kooks devote decades to their dreams. That's not proof one way or the other that this is a well-thought-out device.

The technology was developed in part when Amin was studying at Youngstown State University, which helped launch the fledgling company.

Bill Dunn, an associate professor of mechanical engineering at the University of Illinois at Urbana-Champaign, said that while he hasn't seen the engine in action, he has examined the materials on Entropy's Web site. He said the logic appears sound, but the outcome -- free power -- doesn't make sense.

"It's the end result -- that you can create power from heat at ambient temperature -- that flies in the face of the basic laws of physics," said Dunn, who acknowledges that he hasn't devoted time to figure out why the engine shouldn't work.

"To track down where his thinking may be flawed is a difficult thing to do," Dunn said.

In Amin's favor, Dunn noted that he has attracted backing from "some very intelligent people."

Hedging his bets, Dunn said breakthrough technologies have frequently been greeted with skepticism. "Every time someone suggests something like this, you should at least give them the benefit of an open mind."

But not so open that your brain falls out. Many intelligent people have backed many silly things in the past; that's not exactly a point in favor of the technology actually working.

Iain MacGill, an energy campaigner at Greenpeace, said that because vehicle pollution makes up about a third of US greenhouse gas emissions, a pollution-free engine would be an incredible breakthrough. Nevertheless, it sounds to him like fiction.

"It's got a flavor of 'too-good-to-be-true' about it," he said. "I'm a wee bit skeptical."

And I don't blame him one bit.

That's the end of the article. Reviewing www.entropysystems.com doesn't help much, either. There's a description of the Amin Cycle (the "principle" that claims that energy can be gotten out of heat, and that the engine generates its own heat differential over time by cooling down), but it's loaded with fairly difficult math, and is boiled down to a one-page obfuscated summary. I don't have the physics skills to bunk or debunk this, but it would be interesting to subject this to a serious analysis.

For a more detailed synopsis of the Amin Cycle, I had to give up some personal information. And here we start finding some really questionable things. Amin mentions Carnot's cycle (the heat-differential engine), and says that by considering acceleration, he can get better efficiency than Carnot's. In other words, his engine absorbs heat when it's accelerated and doesn't require a differential. He then goes into a scenario where two cylinders are spun on a varying-speed centrifuge.

He correctly points out that this will generate energy as the gas shifts in the cylinders.

He fails to point out that the centrifuge has to be powered by something.

He correctly points out that energy is conserved according to the first law of thermodynamics.

He fails to point out that any physical system leaks temperature differentials to the outside environment---this is technically conserved energy, since it hasn't exited the universe, but it's not necessarily conserved within the engine.

What these points do is render most of the rest of the equations useless. By not considering outside factors to "prove" that the engine works, he ignores the energy required to get the system going, and ignores the leakage of energy to the outside.

In short, it doesn't work. Oh, it'll work for the slow outboard motor, but it won't work for your car. And even given that, it will still require you to spin up a "starter motor."

The real telling point is in the conclusion, where the last sentence is "Thus changes in entropy are reversible like any other physical process." This *does* violate the laws of thermodynamics, thereby lumping the "Amin Cycle" in with all the other perpetual motion machines that have been invented throughout the years, wasting the time of everyone involved.

In short, I wouldn't plump down $75K for one of these.