Based on some of the comments following my post on the “water car”, I think several people misunderstood the point. It was not to debunk the water car. You can in fact run a car with water as one of the reactants. I could even run a car on crushed ice or Jell-O, if I used the right second reactant.
My point was merely to show how a car could be run on water, and to further point out that it requires a second, very reactive substance. In other words, the “water car” is not running solely on water. The other point was that the reactive substance will always take more energy to produce than you will get back from splitting the water. That’s simply pointing out the thermodynamics. It doesn’t mean that there might not be times that it makes economic sense to do this – just that there is much more to the story than a car that runs on water.
I always thought that running car on water was just a myth cooked up by conspiracy buffs. Turns out, it can be done in theory, but it is just not economical because of the cost of the reactants.
I still say it is a myth. You are running a car on hydrogen which you extract from the water. So what if you get the hydrogen from water? It’s still a hydrogen car.
You could make the same argument about any internal combustion car. Oil is not called a hydrocarbon for nothing.
More over, the energy comes not just from burning the hydrogen, but from braking the chemical bonds of the water molecules. That is what generates the heat that ignites the hydrogen.
But granted, it is not at all like the run on water car of popular myth.
All gasoline is extracted from oil.
(I don’t know this for a fact but let’s say) All hydrogen used by cars is extracted from water.
Gasoline is extracted from oil at refineries. If you invented a miniature refinery that could be put in a car to extract gas from crude the car would not then be running on crude . . . you have simply replaced the method and place of extraction.
The same could be said about this new method for extracting the hydrogen from water.
It is not that a new product has been developed, but a new method of extraction. Perhaps the new method of extraction is better, perhaps not.
But it is deceptive to say that the car is running on water. Without radiator fluid a traditional car wouldn’t be able to function, but we don’t take the cheapest fluid in a traditional car and say it is “running” on that. In the same way, the aluminium compound is the reagent (or “gas”) in this supposed water car. Without the aluminium compound reagent the water is an inert nothing. It is . . . water.
The water is being split (for the hydrogen) and recombined (in the combustion process taking oxygen from air) to form water again. I imagine if the process was perfected you would never have to add more water to your car–you could have a perpetually cycling water system. At that point it would be obvious: the “gas” being used is the reagent–it is what gets consumed and needs to be replaced, not the water.
In this manner we can see that the car isn’t running on water–it is really running on the reagent.
And we are left with the question: Is the reagent cheaper than other “gas”?
Time well tell.
If all you are trying to point out is that it takes more energy to cause water to enter a state of combustion then the combustion of water provides, you are correct. That was the whole point of R2’s post.
But you are incorrect if you think the reagent is the equivalent of gasoline in a more typical combustion engine.
To achieve combustion in any material that is stable you need an energy input. Thus, a gasoline engine needs a spark. The second you lose spark (because your battery connection came lose or whatever) gasoline ceases to combust.
In the same manner, a diesel needs the energy provided by compression to combust. With out the compression diesel will not combust.
In the case of water, it takes chemical energy in the form a a reagent to cause it to combust. But that does not change the fact that it is the water that is combusting, not the reagent.
By way of analogue, imagine that it took more electrical energy to cause gasoline to combust then was provided by the combustion of gasoline. It would be silly in that case to make an engine that ran on gasoline instead of electricity. But it would not change the fact it was the gasoline that was combusting, and not electrical spark.
Your analogy between hydrogen being refined from water and gasoline being refined from oil is false because it is not comparing like to like. It is the hydrogen in gasoline (and all other fuels that we use) that makes it so combustible (carbon can combust on its own in some forms, but it takes a lot more energy hydrogen). That is what I was trying to point you to when I said that it was not for nothing that oil was called a hydrocarbon.
For what it is worth here is Wikipedia’s explanation of the combustion of hydrocarbons…
Combustion of hydrocarbons is thought to be initiated by the abstraction of a hydride radical (H) from the fuel to oxygen, to give a hydroperoxide radical (HOO). This reacts further to give hydroperoxides, which break up to give hydroxyl radicals. There are a great variety of these processes that produce fuel radicals and oxidizing radicals. Oxidizing species include singlet oxygen, hydroperoxide, hydroxyl, monatomic oxygen, and hydroperoxyl (OH2). Such intermediates are short-lived and cannot be isolated. However, non-radical intermediates are stable and are produced in incomplete combustion. An example is acetaldehyde produced in the combustion of ethanol. An intermediate in the combustion of carbon and hydrocarbons, carbon monoxide, is of special importance because it is a poisonous gas.
If we take your reasoning to its logical conclusion, we would have to say that hydrogen is the only real fuel.
In fact, hydrogen is the best fuel there is. That is why the Hindenburg burned up so fast. That is why hydrogen is used to power rockets for that reason. The sun is mostly hydrogen.
But that does not change the fact that we refer to material that is combusting as the fuel. Following convention then, if you are combusting water, it is the fuel.
Also my understanding of how things work leads me to believe you are wrong in saying that that if it was done perfectly you could keep recycling the same water over and over again. But that is neither here nor there. The bottom line is that water is combusting and so it is traditional to refer to it as the fuel.
It seems you are missing my point, but from what you have just said it seems you are misunderstanding what is even going on in this “water car”. I will start with the latter point.
Going to the source (http://www.fuelcelltoday.com/online/news/articles/2008-06/Genepax-unveils-water-energy-fuel-cell) it says:
It is claimed the Water Energy System (WES) developed by Genepax can generate power by supplying water and air to the fuel and air electrodes. The basic power generation mechanism of the system is similar to that of a standard fuel cell. The main feature of the new system is that it uses a membrane electrode assembly (MEA), which contains a material that breaks down the water to hydrogen and oxygen.
Though the company did not reveal any more detail the company president said that they had “succeeded in adopting a well-known process to produce hydrogen from water to the MEA”, similar to the mechanism that produces hydrogen by a reaction of metal hydride and water. However the company claims that compared with the existing method, the new process produces hydrogen from water for a longer time.
Note that it is said that “The basic power generation mechanism of the system is similar to that of a standard fuel cell.”
A standard fuel cell operates thus: “A fuel cell converts the chemicals hydrogen and oxygen into water, and in the process it produces electricity.”
See: http://www.howstuffworks.com/fuel-cell.htm
and: http://en.wikipedia.org/wiki/Fuel_cell
Thus you are mistaken to say in this case that water is being combusted. It isn’t. The hydrogen and oxygen are being split apart so that the full cell can use the hydrogen to generate electricity. The reaction with the water is only a first (pre)step in the fuel cell process. And if you look at the links supplied you will see the electricity produced by a fuell cell is not produced by combustion.
I think you were lead astray by R2’s second post which is a little astray from Genepax’s methodology as he is speaking about reactivity in general. In the first post he focuses more on what precisely they are doing.
So, as I understand how a fuel cell works, and what Genepax says, they are splitting water into oxygen and hydrogen using a metal hydride so that the hydrogen can be used by the fuel cell to create electricity to run the car with the biproduct of . . . water.
Regarding my statement that, “The water is being split (for the hydrogen) and recombined (in the combustion process taking oxygen from air) to form water again. I imagine if the process was perfected you would never have to add more water to your car–you could have a perpetually cycling water system.”
I believe it is true–except that I should not have used the term combustion since the process is taking place in a fuel cell, not a combustion engine.
Let me explain. Take Robert’s example:
NaH + H2O → H2 (gas) + NaOH
The sodium hydride interacts with the water to create hydrogen and sodium hydroxide (lye). Then in a full cell (see the links I provided above) the hydrogen is combined with oxygen from the air (not the original water) to produce water again.
Thus you end up with as much H20 in the end as you began with, and also the NaOH (lye)
So, the water is not being combusted, it is being chemically split. Hydrogen could be combusted (see http://en.wikipedia.org/wiki/Hydrogen_vehicle ) but if hydrogen is being burned it is not being used in a fuel cell–they are two different methods of using hydrogen. Genepax claims they have a variation on fuel cell, so there is no combustion.
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Now on to my point. If you don’t like my analogy about refining–fine. I didn’t claim it was perfect analogy, but you seem to have missed my point in any case. Your analogy about the spark is no better because gas can sustain its own combustion. Yes, you need one teeny spark to begin the reaction but–contrary to your assertion–you don’t need a battery to continue the combustion reaction. A gas combustion engine can feed itself–as is witnessed in the many battery-less gas powered pieces of equipment that are used every day.
The same is not true for the water. A teeny bit of NaH would not make water start a self-sustaining combustion. If it were to combust, it would be a teeny bit of combustion . . . as much as NaH was supplied. NaH is a fuel for the reactive process, (And, as I already pointed out above, in the case of Genepax we’re not talking about combustion anyhow–it is a reactive split, but not a violently combustive one.)
Here is a better analogy:
It would be better to observe that in an gas combustion engine the fuels required are both gas and air. Without air, the gas won’t combust. After the initial spark is provide, gas and air will continue to react until one or the other is consumed/reacted. That is exactly what is going on with H2O and NaH. The two react until one or the other is completely consumed/reacted into the new state of H2 or NaOH respectively.
In a gas combustion engine both the oxygen and gas are consumed/changed. Chemically, they are both “fuel” for the reaction. However, in the vernacular we only call gas the fuel in a combustion engine. Why? Once could say it is because the gas is the more volatile of the two compounds, or whatever. But if gas is the more chemically reactive component in the gas-air combustion engine, then the NaH is clearly the more reactive in the NaH-H20 reaction. Thus, by the very attribute that makes gas the “fuel” in the one case, makes NaH the “fuel” in the second case. (Though I will again point out that chemically in both instances both agents are truly fuel for the reaction)
This finally brings us back to my initial assertion in my first comment that a water car is still a myth and deception.
If this invention is a car that “runs on water”, then the gas combustion engine is a car that “runs on air.” We’ve already done one better.
It is obvious that the second statement is a fantastical myth–but, of course, being true at the same time. Without air, a gas combustion engine won’t work–so it runs on air, right?
But such a claim about the gas combustion engine “running on air” is a myth and deception by nature of omission, as is this “water car.” For a gas combustion engine one needs air plus the (far far more expensive) gas, and for this “water car” one needs water plus the (far far more expensive) metal hydride.
What is good for the goose is good for the gander. If someone tells me they have a car that runs on water, I’ll tell them I have a car that runs on air.
In the comments on R2’s first post he later mentions,
I can’t find a cost for sodium hydride, but the metal hydrides are generally very expensive; something like $100/lb. The reason is that it is very energy intensive, and difficult to produce and handle them. Thus, the dream of throwing some cheap substance into the tank that can turn water into hydrogen remains elusive.[ . . .] Ah, forget to add that for that $100, you get a range of only around 50 miles.
A range of 50 miles for $100 worth of hydride reactant!
Further comments on the post are informative and worth reading. It should be noted that the NaH that R2 uses is only a possible metal hydride example and Genepax may be using a different hydride that may be more cost effective–but nonetheless significantly under performs against the combustion engine–but I also suspect it under preforms against other electric batteries. And, in the end, that is what the Genepax system comes down to–a glorified battery with the electrical energy stored in the NaH.
I hope that helps clarify things.
Eeek!
You are right. I was mislead by R2 second post. I am aware that fuel cells don’t use combustion, I just did not realize that was what the water powered car was using. I saw a clip of water burning on R2 second post and I did not understand from anything that he wrote that the hydrogen was being turned into electricity instead of being burned.
I was not really interested in the car so I did not bother to check the original source. What fascinated me was watching water combust on the Youtube clips.
Since I understood you to be arguing that since the hydrogen was what was being burned so it was incorrect to refer to the water as being fuel, I saw no reason to go back to the source article. That is what comes from being in hurry (and being arrogant to boot).
I am still confused by how you are referring to gasoline combustion engines however. Or I am confusing you, I am not sure which.
You say…
Your analogy about the spark is no better because gas can sustain its own combustion. Yes, you need one teeny spark to begin the reaction but–contrary to your assertion–you don’t need a battery to continue the combustion reaction. A gas combustion engine can feed itself–as is witnessed in the many battery-less gas powered pieces of equipment that are used every day.
Either I am misunderstanding you again, or you have a very misguided understanding of combustion. If all you are trying to say is that the combustion of gas provides enough energy to keep the process going you are correct. But if you are trying to say it only takes one spark to start the process you are very wrong.
You need a lot more then one teeny spark. You need continues sparking for a gasoline engine run. The moment you lose spark is the moment that the engine stops running.
Of course you do not need a battery to run a gasoline engine. I never said that you did. All I said was….
Thus, a gasoline engine needs a spark. The second you lose spark (because your battery connection came lose or whatever) gasoline ceases to combust.
The mention of the battery was just an example of how you could lose spark. I just through in that in to appeal to what I thought was common knowledge. I could have just as easily said that that if you pull the off the spark plug wire on your chain saw while it is running it will cease to run.
I am sure you realize this, but just in case you don’t: All gasoline engines are constantly generating electrical current. Some store this current in battery, others don’t.
In the case of a two cycle engine this power typically comes from a little flywheel. In the case of a car this comes from an alternator. In any case, you must have spark if a gasoline engine is to run (as I am sure you know). This is because a gasoline engine is a series of controlled explosions of an air fuel mixture. That mixture must constantly be set off with a spark. (If it was self sustaining with out the spark, it would not be controlled.)
This principle applies to all combustion. Take a simple bonfire for example. If you took all the heat out of the fire, it would stop even if all other elements of combustion were still there. The heat energy is necessary to combustion.
It does not have to be heat that overcomes the energy barrier. It can also be chemical reaction. But in any case, the presence of fuel and air is not enough for combustion. Something must overcome the energy barrier to start combustion.
Now a bonfire will obviously sustain itself because the combustions of wood generally creates more energy then it consumes, but that does not change the fact that it takes energy to cause combustion. If the the combustion produces less energy then it takes create it, it will not be self sustaining. But it will still be combustion.
And because I am a nerd and a know it all, I will point out that it is not technically correct to equate air and fuel the way you do. Technically, combustion always takes place between a fuel and a oxidant. Oxygen is generally the oxidant, but it is not the only oxidant.
This is why some rocket engines have a tank of oxygen and a tank of hydrogen.
In any case, you were right. I saw R2 post titled fire from water and thought the combustion on the youtube clips was what was running those cars.
“If all you are trying to say is that the combustion of gas provides enough energy to keep the process going you are correct.”
Yes.
“I will point out that it is not technically correct to equate air and fuel the way you do. Technically, combustion always takes place between a fuel and a oxidant. Oxygen is generally the oxidant, but it is not the only oxidant.”
I don’t claim to be perfect in my use of terminology, but what you are saying here only illustrates the analogy I was trying to make.
Another way my analogy could be phrased is “As oxygen is the oxidant in gas-air combustion so is water the ‘oxidant’ in the NaH-water ‘combustion'”