by Scott Robertson
Pneumatic Options Research Library



It's almost too simple for words. It's so easily missed because its discovery does little to gratify the inventor's creative instinct, or the engineer's hard-won high-tech education, or the tinkerer's love of gadgetry. New inventions, theories, and gizmos are so unnecessary as to distract from compressed air's ultimate secret, which is really just efficiency, inherent and designed-in.

Inherent efficiency is made evident by these facts:

Design efficiency is the need to go one step further than status quo convention in the production and use of compressed air. The two-step process of compressing and expanding air creates two opportunities to introduce efficient design measures, that is, to conserve energy.

The ultimate secret of compressed air is that to create a self-sustaining (solar, not perpetual) pneumatic power plant, all you have to do is make the most of the energy contained in expanding air, and make the most of the energy invested in compressing air. Simply put, the self-fueling air engine is a natural phenomenon of ordinary processes, and not some aberration of fringe science or a result of exotic devices. This basic fact is easily proved mathematically using standard engineering formulas and charts.  Gizmos and gadgets are fun, but unnecessary; they are the stuff of research institutes. The first goal should be to show an ordinary air engine running an ordinary compressor and keeping its own tank full in the process.

The idealization of conserving compressor work would be to put the compressor in the tank. The fresh air brought in from outside the tank is compressed into the tank, and the work done in the compressing dissipates into the tank as heat, expanding the volume of air available to the engine as fuel. The increase in fuel value due to the conserving of compression heat represents a value beyond what one would expect from engineering charts but not beyond the scope of ordinary engineering formulas to quantify.

The idealization of conserving expansion potential is to expand the compressed air so slowly that its pressure never goes down, since the heat used to push pistons is replaced by ambient heat absorbed from the surroundings.

This is straight out of the thermodynamics textbook.

The obvious impracticalities of these idealizations are beside the point; it remains only to identify means of going in their general direction. For example:

Gizmos can be added later—such as reducing compression work (as opposed to conserving the work of a normal compressor)—with a series of check valves (and/or jet pump in the tank) that allows low pressure air to be injected into a high pressure tank. Other possibilities include:

If not for compressed air's simplicity, its use in solar power production would have been mastered long ago. We must stop flattering ourselves with our brilliant new ideas, and prove the self-fueling nature of air with basic designs that take advantage of air's best feature: its ultimate simplicity.

FROM FALSE ANALOGIES TO FREEDOM FROM FUEL To state that compressing air gives it the ability to do work is like saying that building a dam gives water the ability to operate a power-producing turbine. While these are true statements, they are not made in the scientific context of energy investments. It would be false to state that the work invested in compressing air results directly in the work compressed air can do, just as it would obviously be false to credit the work of building a dam for the quantity of water power thus made available. In both cases, the work done by the pressurized fluid is a result, scientifically speaking, of the sun's energy, while the work of the compressor, like that of the dam builder, is an incidental investment—you might say an economical consideration or hardware cost—rather than a scientifically correct accounting of the energy invested that later pays off in the power made available.

WHAT'S RIGHT WITH WHAT'S WRONG WITH AIR Some of air's so-called disadvantages, according to the usual way of looking at things—a viewpoint that is built around using air for safety, portability, and convenience, not for efficiency—are some of its greatest advantages.

The classic case of this glaring discrepancy between standard thinking and air's real potential is the assumption that air is self-defeating in any attempt to produce power because of the fact that it gets cold. The standard line goes like this: air enters a cylinder of an air motor and expands, becoming cold in the process. The air subsequently entering the cylinder will be cooled by the cylinder walls, robbing part of its power value before it can do any work. Effectively then, it is a self-defeating hope to try and use air efficiently. My rebuttal is that the cold produced by compressed air's expansion in a cylinder is an advantage because it makes the machinery a sponge for heat in the surrounding atmosphere which, if absorbed into the system because of enlightened design work, becomes free energy for the piston to use.

Let's face it: once Americans get even the vaguest inkling that anyone or anything could be considered wimpy, they shun it like the plague. Could it be that the general ignorance of compressed air's subtle and misunderstood nature is a result of our macho nature, our fear of being associated with sissified ideas?

Once I called the manufacturer of a fairly efficient compressed air motor, and when I asked why the motor wasn't being put in cars, the salesman I spoke to informed me that his boss would remind me that in order for the car to go anywhere, it would have to be followed by a semi truck carrying its compressed air supply.

Now if that isn't self-defeating and wimpy, I don't know what is. It's downright Unamerican to give up so easily!

Similarly, it is thought to be ever-so ridiculous, that a compressor on-board an air car would be the silliest notion since self-chewing bubble gum. All that power wasted, for the little trickle of compressed air made available.

But wait a minute. In what way is all that power used?

It is used to make heat.

And what is it about compressed air that makes it capable of pushing pistons?

It's the heat.

And what is it about expanding air that makes it seem so objectionable as a piston-pushing medium?

The cold produced.

And what does cold do to heat?

It sucks it up like a sponge.

Conclusion: the hotter air gets when it's compressed, the more heat is available to be conserved; the colder the air gets when it's expanded, the more ambient heat it can absorb from outside the engine.


Everything I Needed to Know About Compressed Air,
   I Learned from a Textbook seems nearly impossible to get the scientific establishment to think about the very basic assumptions under which most of us scientists operate.

—Wes Jackson, Land Institute, Salina, Kansas

Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality.

—Nikola Tesla

Rigorous scientific principles are what you want after you've made the discovery. They're the frame for the picture of reality that you've created. But you don't start with a frame and then fit the picture into it. You start with a bloody great glob of inspiration and hope that you end up with something your fellow scientists will recognise as a masterpiece.

—Martin Sherwood, Maxwell's Demon

The assumption that compressed air as an energy carrier contains a portion of the work invested in compressing it is a false analogy.

The power available from steam is a direct result of the power used to generate the steam. Steam delivers, as work, a portion of the same heat energy that had just made it steam; if the boiler were to cool to ambient temperature, no energy would be available. This is obviously not true of hot compressed air just pushed into a tank: after the tank cools down, its contents still contain usable energy.

Thus, the power required to produce compressed air is uniquely unrelated to the power available from it later. We have always assumed, as happens to be true for the steam used as an example above, that the work available from compressed air is a portion of the work that had been done to compress it.

What is this energy that a cold tank of compressed air holds? What form of energy does compressed air deliver? It has been our lapse in reason to assume that the only relevant task is to make the gauge go up on the tank. It is relevant, but not the relevant task, to make the needle rise. The information most relevant to the task of generating compressed air is that the energy delivered by compressed air to an engine or air motor is heat. Heat pushes pistons, while pressure just tells us approximately how much we can do to a given piston, depending also on other factors such as the size of the tank and the size of the piston. So we assume that compressed air is a direct result of the compressor's work because we assume the compressor is putting its own energy into the tank.

But in reality—according to any compressed air textbook that even mentions this whole chronically avoided issue of Where does compressed air's energy come from? —the energy available from a tank full of room temperature compressed air is the same energy that was in the surrounding atmosphere before the air was stuffed into the tank. This is so because all the compressor's work was wasted generating heat. The air molecules heat up due to friction if you try to squeeze them together. You squeeze them together because you want the gauge to go up. But what you should want is for two things to happen. You want the tank gauge to go up and you want the compressor gauge to stay as low as possible while the compressor delivers large quantities of air into the tank; the air is then compressed-by-mixing upon finding itself inside a tank full of pressurized air, and shares its heat energy freely with the air already in the tank. Incidentally, this makes the gauge go up. The everyday compressor uses 100% of its available work energy to add heat to its surroundings, and the result is that a little bit of air gets trapped in a tank and wants out to the degree indicated by the gauge. But the gauge pressure in itself does not indicate how much energy is in the tank.

The relevant goal to refer to in re-inventing pneumatic power systems is often a variation on the theme: mix atmosphere (thus the heat it contains) with a permanent reserve of pre-compressed air , and do this at the lowest possible energy cost.

The result of this process is that a large quantity of heat-bearing atmosphere finds itself trapped and usefully pressurized at such a low energy cost that outside work becomes possible.

The solar air engine is just a more sophisticated version of using wind to propel a sailboat, and it is just as revolutionary as sailing ships once were, because it's just as groundbreaking in its implications for humans and for this planet, and just as solar.


Twelve Principles of Efficiency in the Use of Compressed Air to Drive an Air Engine


How to Double the Power Value of a Dollar's Worth of Compressed Air, by Spending Only 10 Cents

Excerpt from "Compressed-Air Motors," Harper's Weekly, December 5, 1896

When compressed air was first tried, it was found that the loss of power was enormous. It was difficult to store, for the air leaked rapidly away; it was expensive to generate, and there were thermo-dynamic difficulties in its use without number. When a thousand cubic feet of air is jammed into the space of one, a large amount of heat is developed, and in order to store and use the air this heat must in some way be drawn off. Similarly, air at high pressure, when released, cools rapidly. The result, if there be a sufficient moisture, is freezing and clogging. For a long time it was thought these difficulties were largely insuperable.

Now, however, these very difficulties are turned to a profit—to such excellent profit, indeed, as to afford an apparent paradox. It seems idle to assert that it is possible to get as much power out of a machine as you put into it—this means a frictionless and wasteless mechanism. And yet a very near approach to just this condition seems to have been made in the case of compressed air. This is due to the development of the reheating process. Lest the reader be not familiar with the technique of the subject, it may not be idle to explain its broader features. In the process of compression the air is sucked into a piston, and then rammed into a reservoir surrounded by a water jacket, the latter drawing off the heat generated in the compression. The machine which does this work is a beautiful affair of what is known as the four-stage type. That is to say, the air is first driven up to about eighty pounds pressure and cooled; then turned into a second cylinder, where it is compressed still further, then cooled again; and so on up to the desired point. Thus even at two or three thousand pounds pressure to the square inch the air within the reservoir remains at somewhere near the temperature of the outside atmosphere. But if the air be used in this condition, not only will a large share of the power employed in compression be lost, but it will, as already noted, have a tendency to freeze everything within reach. If, however, as it is released, it is passed through a heater or is shot through superheated hot water it will, under the well-known properties of air, enormously expand. In actual practice it has been found possible to add, by reheating, one horse-power to each horsepower developed by compression, at one-eighth or one-tenth the original cost of the latter. That is to say, if a given quantity of compressed air costs a dollar to generate, the further expenditure of ten cents in reheating will double its power to do work. Theoretically the total efficiency thus obtained is actually greater than if the same amount of coal had been burned in an ordinary steam-engine and the power thus generated used direct. In practical use it is slightly less.


Bob Neal's U.S. Patent No. 2,030,759: Compression unit compresses air for free (1936)

Bob Neal's compression engine works for free, making more compressed air than it needs to run on, for the purpose of operating auxiliary equipment. He had it running an engine lathe, for one thing.

When the Patent Office informed Bob Neal that his patent claim would be denied because it was a round robin device with no function, he built a miniature working model, put it in a suitcase, and took it to Washington DC. His fellow Arkansan, the so-called "97th Senator", got him an audience with the Patent Office.

He plopped the engine down on the patent examiner's desk, turned it on, and requested that he be granted his patent on the basis that the engine worked. His request was granted.

When the patent was published, he was visited by Germans who requested that he share his secret with them. Their request was not granted.

The visiting Nazis borrowed Bob Neal's daughter, and once again requested that he share his secret with them. He took his working models apart and scattered the pieces around the countryside. He informed the Nazis that he was through with the engine forever, and requested that they return his daughter, which they did.

That was a few years before the U.S. entered the second world war. At that time the German soldiers or officials or whatever they were would have been free to roam the U.S. the same as any other tourist.

For decades I've been trying to imagine and research how someone would go about getting a pressurized air tank to admit more air without providing a resistance to such inflow. Air car inventor George Heaton phrased it "putting low pressure air into a high pressure tank." Bob Neal had passed his project on to a Mr. McDonald who passed it on to me. McDonald used the phrase "the valve built up pressure" in the special double-valve "equalizer" in the tank. So it appears that either there's a way to inject low pressure air into a tank and let the tank air compress the fresh atmosphere for free by pressure equalization or mixing, or else there's a way to get the compression process to bypass the compressor and do its work between two check valves inside the tank, so that all the work of compression (heat) stays in the tank and gets used as working energy for the system.

Researchers around the world have taken on the task of reproducing Neal's proven results, mostly in secret, but for those who believe, as I do, that we should be working together to stalk down Bob Neal's mysterious equalizer, I have established a public and private forum here. Join us today and participate in the good work. It is my goal to put the backyard mechanic back in the backyard.


How the Mis-invention of the air engine got us to where we are today: with an air engine that burns gasoline

In 1670, Christiaan Huyghens devised the first-ever engine, made up of a cannonball acting as a piston in a vertical cylinder. An explosion of gunpowder under the ball raised the ball up the vertical cylinder, then it would fall back down the cylinder under its own weight. This pumping engine worked because of the suddenness of the motion imparted to the cylinder's contents by the explosion. Behind the high pressure explosion pushing the ball up the cylinder, there was an implosion, a sudden state of partial vacuum or rarefaction wave, in the cylinder. Because of the sub-atmospheric pressure, or depression, in the cylinder, the atmosphere added its own energy to this engine cycle to force the next cylinderful of water into the rarefied space under the ball. Then the ball fell back down the cylinder, pumping the water back out. Each explosion would scavenge the cylinder by clearing it of any water left over from the last cycle, by means of a high pressure blast or compression wave.

Huyghens' basic discovery—the depression left inside a closed cylinder after a sudden outward pulse—was the working principle that Thomas Savery used in taking the engine to the next stage in its development. The alternating wave in the pumped fluid was a fluid piston that did the pumping. Pulses of steam alternately scavenged the two chambers of Savery's engine, and each chamber would automatically refill with water because of the depression left behind each scavenging pulse. Savery's engine had no moving parts except valves. The mass exit of the chamber's contents left a depression that induced the next chamberful of water, and a pulse of steam pumped this water out. The pulsometer pump, which was manufactured from 1876 to at least 1938, used the same principle.

Newcomen's and Watt's cumbersome piston engines, laden with moving parts, took precedence in the developing engine industry over the simpler fluid piston principles that Huyghens and Savery pioneered. This was, in effect, an early version of engineered obsolescence. If we hadn't been in such a hurry to get in our cars and go, the pulse pumping engine might have gotten there first, in which case we'd all be driving air cars right now. Instead, compressors were designed to look like piston engines.

Bob Neal's patented Compressor Unit is the basic idea of the essential hardware needed to run a self-fueling air car. Neal filed his patent in 1934; a trip to Washington with the working model secured him a patent in 1936; shortly thereafter he had to abandon the project due to harassment by the Nazis. The Nazis perfected the pulsejet engine in 1943; the French were developing their own pulsejet at the same time. This pistonless piston engine—a tube containing a resonant fluid piston—proved to be the most powerful engine for its size that was ever built. And none of the pulsejet's inherent defects, such as high noise levels or wasted residual energy in the exhaust (or the fact that it propels bombs), apply to Neal's equalizer. since the equalizer is inside a tank full of compressed air.

Michel Kadenacy filed the first of his French patents on August 1, 1933. Kadenacy's system of acoustically scavenging and charging an engine cylinder is still the theory behind two-stroke engine tuning. The Kadenacy Effect could be called the Huyghens Effect, but Huyghens already had a principle named after him, also having to do with waves. The work of Huyghens became the foundation for the work of James Clerk Maxwell, the founder of mathematical prediction in theoretical physics, who described symbolically the future discovery of dynamic pressure exchangers—Maxwell's Demon—in his textbook Theory of Heat in 1870.

Arkansas shoemaker Bob Neal's compressor unit is Maxwell's Demon reduced to hardware, and it's also the logical idealization of Huyghens' first-engine-in-history. As an improvement on a solar heat pump within a Thermodynamic Generator it ranks as the oldest of new ideas. "The Neal Equalizer as Energy Sponge" will one day be considered a refinement in engineering thought that paved the way for the age of sustainable technology to take hold in the 21st century.

Meanwhile, the Earth is still flat.


For very large conspiracies to work over large geographical areas and for decades at a time, the conspiracy must be transformed into something else—a belief system, an ideology, a world view, a concept of proper professional behavior, even a crusade.
—Angus Wright, The Death of Ramon Gonzales: The Modern Agricultural Dilemma