So you’re asking if you can get more energy out than you put in? That’s what is being claimed in the ads.
It sounds like you understand the immutable laws of thermodynamics. Are you being misled by the hype into thinking this isn’t a factor?
If you were going to break water up into hydrogen and oxygen (a no win proposition) why would you only use the hydrogen for combustion? Based on limited information about the use of hydrogen as fuel it seems like you might do better improving the combustion with the oxygen if you had to pick just one of the elements.
But then the oxygen will use up all the hydrogen, and you’re back where you started!
This was on the dope many years ago and I think it made the news. The basic idea was that the speed of detonation was much faster in hydrogen then the other fuels (gas or diesle) so the hydrogen would carry the combustion more evenly in the cylinder and improve efficiency. This improved efficiency would offset the energy input in creating the hydrogen.
How about if you put a big solar panel on the roof of your car and used sunlight to break water into Oxygen and Hydrogen? Why waste all that free solar energy? (Might make the inside of your car a little cooler, too…)
I suspect the issue is practicality - if you break the water as you get power from the panel, you have to store the hydrogen, which probably means a compressor etc.
If you store the power, you need a battery, adding weight.
And the amount of power they currently generate is pretty tiny, which is why you see those massive solar powered cars weighing as much as a feather in order to generate motor power directly, so they’d probably struggle to generate enough hydrogen anyhow. You’d need a pretty big benefit to make the cost and complexity worth it.
Otara
Well, duh. They’d change the water for gasoline.
Mythbusters did a segment on all of these miracle fuel systems (including hydrogen) and found they were all scams. None of them improved efficiency at all. The best of them had no effect; some lowered fuel efficiency; and some wouldn’t run the car at all.
Weight issues. The extra weight will offset any gain. Mind you a solar panel trailer thing next to a parked car, charging it, can work.
In other words, P.T. Barnum was right.
This is just about the only sort of claim that makes sense in this scenario - that maybe the hydrogen does something to the process of combustion - not necessarily making it more complete, but maybe altering the rapidity or even-ness, however:
It seems unlikely that this would just coincidentally happen to be the case in an engine where it was never considered in the design, and in any case the practical conversion losses involved (thermodynamics aside) make it unlikely that this could ever be a winning proposition.
That is, Hydogen would have to effect a really extraordinary change to the way that petroleum burns in an engine, in order to offset the losses in converting mechanical to electrical energy and the losses in using electricity to split water.
For a given fuel, yes, the modern internal combustion engine is just about as efficient as it can get, and yes, combustion efficiency (the % of fuel converted to exhaust products) is upwards of 98%. The only way to improve efficiency is to reduce the amount of heat being dumped out the exhaust and/or out the radiator.
But efficiency can be improved by adulterating the ordinary gasoline fuel mixture with a small quantity of hydrogen and making some modifications to the engine:
-hydrogen adulteration increases resistance to knock, so you the compression ratio can be increased.
-hydrogen adulteration increases flame speed, enabling reliable combustion of lean mixtures and also releasing more of the fuel’s energy near TDC instead of later in the expansion stroke. Lean mixture burn cooler, losing less heat to the combustion chamber walls and leaving more to be converted to mechanical work.
While hydrogen adulteration does have the potential to improve fuel economy, aftermarket systems like the one referenced by the OP won’t make a difference:
-changing the compression ratio requires removal of the cylinder head so that a thin layer of metal can be removed from the bottom, reducing combustion chamber volume. Racers/gearheads do this from time to time, but it’s not an easy/cheap modification for the average car owner.
-switching to lean mixtures requires an aftermarket programmable ECU in order to fiddle with the fuel map.
-taking advantage of the faster combustion requires a similar degree of fiddling to optimize spark timing.
optimizing fueling and spark timing requires a significant investment of time and expertise in an engine test cell. By the time a buyer of an aftermarket hydrogen system has done all this work, his car will be more efficient, but it won’t be possible to drive it far enough to recover all of that expense.
A couple of reasons you won’t see this on mass-produced vehicles:
-lean operation tends to produce more NOx, a regulated emission. Moreover, lean operation prevents the standard three-way catalytic converter from effectively converting that NOx back to its constituent oxygen and nitrogen. If NOx were not so tightly regulated, you probably would already have seen lean-burn engines (without hydrogen enrichment) on the market. (I am not arguing for relaxation of emissions rules here; I like having clean air to breathe.)
-most vehicle owners do not want the additional hassle of having to maintain a second consumable fluid on board the vehicle. They struggle just to keep an eye on the fuel gauge, and now they’re also supposed to keep an eye on the water gauge? Screw that; they’ll just buy a smaller car that has the MPG they want without the added hassle of keeping a water tank full.
Magical water-powered increases in fuel economy seem to be a pretty popular topic when fuel prices spike. Cecil covered the idea in his column, “Can you really get better gas mileage using your car’s engine to make ‘Brown’s gas?’” (September 12, 2008). In addition, some previous threads are here:
Hydrogen power in a car, no fuel cell (6/04)
Isn’t this a perpetual motion machine? (11/05)
Motors running on water (6/06)
Please Settle the Daniel Dingle Debate (10/06)
Any validity to this? (H2O–>HHO power) (11/06)
Cheap hydrogen generation… is this bunk? (10/07)
“Water Powered” cars (4/08)
water as fuel (6/08)
Can water as additonal auto fuel work efficiently? (6/08)
Can you really get better gas mileage using your alternator to make “Brown’s gas?” (9/08)
As multiple people have already said in this thread, there’s a nugget of real science here: use of hydrogen can change the combustion in the cylinder, and that could be enough of a change to increase efficiency to the point where the additional power produced offsets losses in the electrolysis system.
But that’s part of the problem: the nugget of real science pastes a thin veneer of plausibility over the “run your car on water” scams. There are multiple issues with marketing a retrofit kit for an existing car, many of which have also been mentioned above. In addition, the scam ads I’ve seen always claim an implausibly high mpg gain, cite completely bogus physics, or (usually) both. If you see any of the following statements:[ul][li]Claims of over 10% improvement in efficiency (even worse is 30%, or 50%)[/li][li]Claims that water is not the lowest energy state for H and O, and additional energy can be extracted from same.[/li][li]Statements that a large percentage of the fuel (like 30% to 50%) is never burned in the cylinder (and addition of hydrogen decreases this large percentage)[/ul][/li]…then it’s a sure bet the technology is bogus.
Also (too late to edit the previous post): from the link in the OP:
Sure sign of bogosity (not that there was any doubt anyway).
Have you read the research? Is the efficiency gain for the gasoline combustion actually enough to make up for the energy required to produce the hydrogen, and the extra weight of the hydrogen-producing/injecting apparatus?
I haven’t investigated it beyond the link I provided upthread - but a link on that page leads here, where they claim that by using a plasma reformer on hydrocarbon fuel (as opposed to electrolysis on water), they can produce hydrogen (and CO, another helpful adulterant) at a much lower energy cost. Upthread I forgot to mention one additional source of efficiency gain: reduced pumping losses (for a give power output, lean burn means you open the throttle more). They claim theoretical overall vehicle fuel economy gains of 20-30 percent. That was written in 2005; I don’t know whether they ever developed a working prototype.
What they describe seems plausible, but again, none of these gains will be realized by the OP or anyone else strapping an aftermarket system to their otherwise-stock vehicle.
Transportation companies measure fuel costs in pennies per mile. I’m sure if there was an advantage to installing a hydrogen injection system you’d see it in every commercial vehicle on the road.
more than that, the design of the combustion chamber itself as well as the bore and stroke of the engine all come into play. Burn rate is pretty well understood and the overall engine design has to account for the intended fuel. Same reason all cars can’t be flex-fuel even if the fuel system materials are compatible with ethanol.
A short correspondence:
And, predictably:
Heh.
Or! We could put a wind turbine on top of the car, so the faster you drive, the more energy you create!