If nothing else, the tragic Gulf oil spill of 2010 serves to remind us not only of how reliant we are on supplies of energy, but also, just how much we must endure to keep the supply flowing. But more than oil is spilling out of this chaos—whenever an event such as this takes place, all sorts of ideas, claims, and promises pour out as well.
Some of what’s being proposed in the way of automotive technology is grounded on sensible physics and engineering know-how. However, there’s just as much—perhaps more—bogus material creeping into the mix. Here, we attempt to separate fact from fiction.
THE CLAIM: Engineers built a carburetor that would allow any automobile to get more than 150 mpg, but the oil companies or car manufacturers bought the patents and suppressed the technology.
THE TRUTH: Myth. Such a device is impossible.
The carburetor is fast becoming an automotive anachronism—like white-wall tires and eight-track tape players. A carburetor mixes gasoline and air in the proper proportion to combust in the cylinders of automobile engines—much as the lungs of our bodies mix air and “fuel” (carbohydrates) in the proper proportion to drive our own biological “engines.” While carburetors can still be found in small-engine applications (e.g., lawn mowers), in automobiles, they’ve largely been supplanted by computer-controlled fuel-injection systems. The myth of the 150-mile “carb” is more interesting from a historical, rather than a practical, perspective. However, it’s probably only a matter of time until, again, someone “invents” 150 mpg fuel injection.
Basic engineering and the laws of physics preclude such a device on theoretical grounds. However, a convincing proof can be provided quite easily without resorting to any of that high-brow stuff. Here’s how: A typical car achieves about 25 to 35 mpg, but strapping one of these “wonder carburetors” on the engine purportedly increases this number to 150 mpg and beyond. We can infer that the increase in fuel economy scales with an increase in the total efficiency of the automobile’s power train—in this particular case, we’re looking at a four- or five-fold increase in efficiency. But this introduces a problem: Most engines are already operating at 25% efficiency—even a four- or five-fold increase in efficiency means that the engine is now operating at 100 to 125% efficiency!
A 100% efficient car means no waste heat, which then would require no cooling system. Radiators, water pumps, cooling fans—all become superfluous. Moreover, no heat means a cold car in the winter. True, you could burn some gasoline to provide some heat, but then, you would reduce your fuel economy as less energy is left to move the car. Get the idea? Oddly, believers in the 150-mpg carb always seem to avoid this logical discourse—and for good reason.
The carburetor is reasonably efficient at mixing fuel and air—fuel injection is even better. No doubt, improvements to either of these systems will continue to be made, but don’t expect efficiency gains of more than a few percent, at most.
THE CLAIM: An automotive generator small enough to fit in the trunk of a car can convert waste electricity into hydrogen gas.
THE TRUTH: Myth. There is no such thing as “waste” electricity. If an increase in fuel economy is your goal, skip any such devices and invest in a set of good tires and drive slower, instead.
All cars come equipped with an alternator to supply electricity for various purposes, such as lights. The automotive alternator operates on the same principle as the alternator in a wind generator: Rotary motion from the engine is transformed within the alternator (by spinning magnets or coils in a magnetic field) into good, old-fashioned electricity.
Over the years, proposals for tapping off some of that electricity and using it to split water into hydrogen gas by way of electrolysis have appeared and reappeared many times. Hydrogen, as we know, can be burned in engines. The faulty premise lurking in this myth is centered on alternator efficiency and that of all subsequent processes.
First, no alternator is 100% efficient—50% is about the best that can be expected from an automobile version—which means that for every gallon of gasoline that’s burned to operate an alternator, half of that energy is immediately lost as heat. But that’s only the start.
Converting electricity into hydrogen gas via electrolysis, while easy to do, is only about 80% efficient—tops. Moreover, the chemical-to-mechanical conversion efficiency attained with hydrogen fuel in a conventional engine is limited to about 30%. Of the energy that could have been used to power the car directly, something like 75% was wasted in these two steps alone.
THE CLAIM: Many popular hybrid cars on the market get about 150 miles per gallon.
THE TRUTH: While a 150 mpg plug-in hybrid may one day become a reality, the best of hybrids on the market today only get about 50 miles per gallon.
This claim is particularly irksome given its recent ubiquity. The fallacy is not one of technology but, rather, terminology—specifically, the term miles per gallon and the ambiguity that can arise in the context of plug-in hybrid vehicles. Such ambiguity is, however, avoidable if the general public will accept that hybrid cars require hybrid fuel economy ratings.
Here’s how one form of the reckoning goes: Suppose you own a plug-in hybrid and decide to go on a 42-mile trip. You drive the first 40 miles in pure electric mode before exhausting the batteries. Then, the gas engine kicks in to complete the remaining 2 miles. Let’s assume that the gas engine has a normal fuel economy of 25 mpg. This will make the calculation easier. Here’s where things can get creative: If you take the total distance traveled and divide it only by the gas consumed, you arrive at an mpg rating of 525 mpg!
The source of this absurdity originates in the computation: One cannot arbitrarily ignore the electric energy in calculating the fuel economy. To do so invites all sorts of silly results. For example, a pure electric vehicle, consuming no gas whatsoever easily achieves an mpg rating of infinity by this reckoning.
To be fair, some officials are trying to come up with a metric that gives owners a sense of the mpg rating in terms of “gasoline-equivalent gallons.” Unfortunately, even this approach has problems. In the end, what really makes sense is simply to state how far a vehicle will go on a gallon of gasoline or a kilowatt-hour of electricity—for both EVs and PHEVs.
A disturbing aspect of this myth is that more and more people are making similar claims for PHEVs. If this continues, the auto industry may have a lot of disgruntled buyers on their hands when they find out that their new car only went 40 miles on a gallon of gasoline—instead of 150 miles—somewhere on a lonely stretch of road, say, in Wyoming.
Electric and plug-in electric vehicles are wonderful technologies. They promise to help wean us off fossil fuels if they derive most of their energy from renewable electricity. The technology is at our doorstep, but if we insist on providing a “gallon of gasoline equivalent” in hope of avoiding confusion, we will, ironically, do just the opposite.
THE CLAIM: Miracle gas pills will increase your fuel economy.
THE TRUTH: Myth. Avoid miracle gas pills and all variations thereof.
During a talk one year at a local energy fair, I picked up a pamphlet that read, “Miracle gas pills will increase your fuel economy by a guaranteed…”
The “miracle” pills were nothing more than solidified naphthalene—also known as mothballs—a hydrocarbon derived from coal tar. Yes, mothballs will burn when dissolved in gasoline; so will any number of soluble hydrocarbons, like two-cycle oil! True enough, these pills will increase the total distance you can drive on a gallon of gasoline—perhaps as much as one-hundredth of a mile.
Given the cost that some vendors are charging for this “product,” you can figure on motoring down the road for a price that’s easily as high as ten times what it would cost you to use ordinary gasoline.
And then there’s the issue of what mothballs might do to your engine.
THE CLAIM: Perpetual motion or “free energy” machines provide more useful energy than they consume.
THE TRUTH: Myth. These machines are a hoax and unsubstantiated by tested established physical principles.
Sadly, this last myth has been around for nearly a century, and is one of the most damaging—especially to the pocketbooks of well-meaning investors. All of these machines claim to produce unlimited or vast amounts of energy from seemingly nowhere—a sort of bottomless pit of energy. Common buzzwords used by promoters are “magnetic,” “over-unity,” “quantum,” and “dark energy.”
One of the great triumphs of physics was the elucidation of the laws of thermodynamics. We’ll focus on the first law: Energy, like the cookies in a cupboard, doesn’t just appear or disappear into thin air. It may be transformed—taking another form like the extra pounds on our hips—but it is a constant quantity. If we take pains to account for all the transformations that energy can undergo, the total amount of all these forms in the end can never exceed what we started out with. This, in a nutshell, is a statement of the first law of thermodynamics.
Proponents of “free energy” tend to ignore this law, for obvious reasons. But when asked to provide proof of their claims for various “products,” vendors invariably hem and haw with declarations like, “Our prototype unit is under repair, but we’ll get back with you. In the meantime, for an investment of only a few thousand dollars…”
It’s pretty clever when you think about it: No machine, but plenty of slick advertising to gain investors in a product that’s “perpetually” under development.
There are many energy-related claims concerning automobiles—some true, some exaggerated, and some just downright bogus. Consumers interested in making smart choices need to be on their toes. All too often, a snazzy, sophisticated-sounding description is nothing more than a smoke screen for a product of dubious value. Do your homework, and keep close tabs on your wallet. Talk to professionals before making decisions that might turn out to be costly mistakes.
Dominic Crea is a published author and the director of Science Wonders, an educational program devoted to helping people learn about and implement renewable lifestyles. He is a physics instructor at Oakland University and also teaches at the annual Midwest Renewable Energy Fair in Wisconsin.