Water Powered Car??

September 2008

Water-powered cars drive me nuts. I want one so bad!! -- The only problem is that the water-powered car is not real and too often it gets thrown into the same discussions with emerging technologies that really are real, such as hydrogen cars, fuel cells, six-stroke engines, vegetable oil, biodiesel and other biofuels, electric cars and the like. That association erodes the credibility of the legitimate technologies, making them all sound kind of fringy.

The idea of a car that runs on water is so alluring that many people are willing to overlook the fact that it's not possible, especially if there's any chance of selling you something. Most of the misinformation about water-powered cars or hydrogen "boosters" comes from one individual who runs a business selling stuff to people who believe it's possible:

www.waterpoweredcar.com

Oddly there's not much literature about why this whole concept does not work. I guess there's no money in disproving it and no glory in poking a pin in the dream water balloon. Or, as one forum post I read put it "The reason that won't work is so obvious it would be embarrassing to spend any time explaining it."

Well I have no shame and after much frantic research I present you with some of the physics myths and problems behind the water-powered car and HHO or hydrogen "boosters" and water-powered-cars:

1. Thermodymanics: The act of breaking water into hydrogen and oxygen by hydrolysis (ie: using electricity, as all in-car systems do) is governed by thermodynamics. Which is to say, it will take at least as much energy to split the water into gasses as you will get from recombining them (by burning in an engine, for example). In fact you will loose a lot of energy to the inefficiencies of the processes used to split them and recombine them.

2. Some boosters are more than 100% efficient: This is a flat-out lie and is the central fallacy of most HHO systems. If this were possible we would live in a very different, highly unstable universe. In this universe no energy transformation is "more than 100% efficient". The most extremely efficient laboratory hydrolysis equipment is around 75% efficient and most industrial systems are 25-50% efficient. Special additives and catalysts in the hydrolysis tank can help improve efficiency but never to 100% and certainly never beyond. This is a limitation of physics, not technology. This website from the physics department of Georgia State University breaks down the energy exchange in hydrolysis:

http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/electrol.html

This page from Stanford University has lots of interesting facts about real hydrogen cars, and states right off the bat: "the law of conservation of energy tells us that all the energy to be obtained by burning the hydrogen must be supplied by the primary source... Of course, since these processes aren't 100 percent efficient, there is some loss of energy":

http://www-formal.stanford.edu/jmc/progress/hydrogen.html

Converting the hydrogen back into some kind of work is also inefficient. This page explains how it is impossible to get more than 20% of the energy back by burning the hydrogen in an internal combustion engine:

http://en.wikipedia.org/wiki/Water-fuelled_car

That means we are loosing around 50% of our energy making the hydrogen, and then loosing 70% of what is left by burning it. That does not even take into account the loss from the engine converting gasoline to electricity in the first place, which in itself is less than 20% efficient. Overall, an in-car hydrolysis system can only hope to produce a tiny fraction of heat-energy in the form of hydrogen compared to the heat-energy of the fuel used to make it. How inefficeint the system is depends on each part in the chain but it can't be more than 10% efficient end-to-end.

3. But I've got the resonance (or the catalyst), man!: Resonance, or pulsing energy at specific frequencies that focus energy where it can do the most work, functions almost exactly the same way catalysts do (see above). They both help to reduce the inefficeincy of an energy transformation with the goal of getting as close to 100% efficient as possible. Niether one can go beyond that limit. Gains in efficiency are like discounts: "Get 50% off if you bring a friend!" does not mean the they are going to pay me 50% if I bring three people.

4. Burning hydrogen in a gasoline car: Most boosters work on the principle that if you just throw some hydrogen gas into the air intake, it will burn in the engine such that you will get some extra forward motion. The problem is that almost every car in existence measures the amount of fuel it uses as a ratio to the amount of air going into the engine. Adding flammable gases to the air will not cause the engine to use less fuel, it will simply run richer and more unburnt fuel will go out the exhaust. It is possible to modify an engine to anticipate the incoming hydrogen by using less fuel for the same amount of air but as we will see later, the amount of hydrogen coming from an in-car hydrogen booster is not enough to make a real difference in how much fuel will be needed anyway. The point is, even if there was a free source of hydrogen, simply blowing it into an unmodified engine is not going to do anything. Popular Mechanics took the time to hook up test equipment to a car's fuel injection system and determined that the amount of fuel used was not reduced even when a very large HHO booster was hooked up:

5. Hydrogen has a "catalyzing effect" on gas and diesel fuel: The idea is that hydrogen has a chemical effect on hydrocarbons which allows them to burn more completely and that the heat-energy of the hydrogen is not what is "boosting", rather it is helping the primary fuel to burn better. While this effect does in fact exist, is very very slight. The effect is not even measurable in an engine that has not been extensively modified to use both hydrogen and gasoline. Those modifications would include: a dedicated fuel injection system for the hydrogen, a new ultra-high compression cylinder, etc. Essentially a purpose-built engine. This article talks about one project:

http://www.greencarcongress.com/2005/11/hydrogenenhance.html

The benefit is really around reducing the knock and lean limits which would allow the development of a smaller, higher compression engine:

Even with a special built hydrogen/gasoline engine these researchers only predict a maximum of about 25% improvement in efficiency.

This whole idea is apparently borrowed from research into other fuel catalysts like propane which actually do have a significant catalyzing effect. Unfortunately even propane is not economical as a catalyst and is only used in small, experimental setups.

6. The electricity in a car is "free": The misconception is that because you don't pay for the electricity directly, the electricity must be "free". But in fact car engines must burn fuel to make electricity and they are not especially efficient at it. Furthermore, modern cars only make as much electricity as they need so if you hook up something that draws a lot of electricity, like a small hydrolysis unit, the car will burn more gasoline to make the electricity to run it.

7. How many gallons of water per mile?: For those of us who actually _do_ live in a different universe where people split water into hydrogen with a magic wand, how much water would it take to drive a car? By weight, hydrogen has around three times the energy of gasoline. Water, by weight, is mostly oxygen (H20 is two hydrogen atoms for each oxygen, but oxygen is 16 times heavier than hydrogen). Therefore, one gallon of water is 1/7 hydrogen by weight meaning you would need more than two gallons of water to make enough hydrogen for the equivalent energy of one gallon of gasoline. A teeny-tiny HHO booster that holds a liter or less of water faces a terrible problem of scale, there's simply not enough hydrogen in that water to make a difference even if there weren't problems with the energy efficiency of the whole transaction.

8. But it seems like I'm getting better mileage! Nobody gives very accurate measurements when they talk about HHO boosters and part of this is only natural: it's very difficult to accurately measure a car's fuel economy and most people have never even tried before they install a booster. Economy varies a lot with driving style and because we never run our cars completely out of fuel (at least not on purpose), there's no way to account for the few gallons that are in the tank when we decide that it is "empty". If your tank only holds 15 gallons and you can only determine "empty" within 2 gallons (which is optimistic) you have a measurement error of 13% from that factor alone. Unless you fill-to-spill you rarely have a good idea of what "full" is either. Overall, fuel economy measured on a single tank is going to have an error around 20% and will respond well to subjective bias.

The easiest way to get a better measurement is to do it over the course of a few tanks, measuring how much fuel is put in and the odometer at the start and end. Only the start and end of the series needs to be at empty. If we log that for say, 40 gallons the filling error drops to around 5%, after 100 gallons it gets to 2% - plus the driving style error is smoothed out over time too so the total error can hopefully drop to a more reasonable amount. The measurement error of the volume of fuel becomes the dominant effect so that has to be reasonably accurate.

9. So can I still put water into my engine? Astonishingly enough, the answer is yes! - or maybe! A completely different approch called water-injection does improve fuel economy (very slightly) by spraying a high-pressure stream of water into the intake of a turbocharged gas or diesel engine that does not have an intercooler (an intercooler accomplishes the same effect without the use of water). An important distinction is that these cars are are not "running on water" but rather using water to help manage heat in the engine. Most modern turbocharged engines already have an intercooler so this pretty much only works with older cars.

10. Come on, please... I really really really want to "burn" water in my car!: O.K. I must admit that it is theoretically possible to get more energy out of the hydrolysis of water than you put in if you feed the hydrogen into a nuclear fusion reactor rather than a fuel cell or an internal combustion engine. Fusion reactors of any size are not practical at this time and if they ever were, it would be vastly safer to drive an electric car and charge it from a fusion reactor rather than risk turning the earth into a second sun by driving your car into a pool, or even worse (if there can be anything worse than the total destruction of the earth)- turning the earth into a black hole if you happen to be driving around in switzerland near the large hadron collider!

-Kanoa