Is Hydrogen Economy Viable Without Fusion Energy?

[russ_watters]

Here's some work that focuses on hydrogen supplementation via a plasmatron gas reformer developed by researchers at MIT. There are some pretty outrageous claims for efficiency improvements in the pdf file.

http://www.psfc.mit.edu/research/plasma_tech/PDF/dan_cps.pdf

Now that's interesting. It says that by using hydrogen injection, you can increase the effective octane number. This does nothing whatsoever for an existing car engine, but it would allow the use of higher compression ratio engines, which is the key to higher thermodynamic efficiency. I don't know why they mention turbochargers, though - those are an efficiency improvement you can already bolt to just about any car.

 

[buffordboy23]

I don't know why they mention turbochargers, though - those are an efficiency improvement you can already bolt to just about any car.

The turbocharger would likely permit the car to run ultralean. The hydrogen would protect the engine due to its influence on combustion properties. Efficiency will increase.

The NASA article posted by RMForbes actually looked at hydrogen being used to extend the lean operating limit of an engine.

 

[RMForbes]

You threw a lot of scientific words around in previous posts, but this paragraph shows you really have no idea what thermodynamics even is...Gas engines are thermodynamic engines...You really need to get onboard with this concept. If you don't understand why it is, you need to learn...No, RC. Now you're dealing with both crackpottery and conspiracy theory. There is no mass production vehicle in any country that utilizes hydrogen generation/injection.

You are right, I'm not a scientist. I'm a technician by profession. I take ideas from the researchers, designs from the engineers, and make them work. I may not have the terminology correct but I understand the concepts. I know these technologies are real by hands-on experience. I have done several experiments, some successes and some failures. I installed one of my successes on my personal vehicle almost a year ago. It still works great. Through experimentation is where real knowledge is gained. Dismissing ideas, no matter how far out they seem to you without experimenting, is not good science. I cannot remember any major innovation that was not called a crackpot idea by the people of the day. I happened onto a website the other day that listed just about every technology in common use today and the reactions by the respected people of that time as they demeaned the technologies. It was enlightening.

I suggest you review the MIT link again. Do you really think they are the only facility researching this technology or developing similar products?

I can understand your comment about conspiracies, but just because I think they are out to get us, doesn't mean they aren't.
Do I believe that the Oil industry has too much power? aaaaaaaaa yes!
Do I believe that they have used their power to stifle new technologies that threaten their market dominance? Guilty.
Have their lobbyists written most of the current legislation regulating their industry? Without a doubt.

 

[russ_watters]

I may not have the terminology correct but I understand the concepts.

No, you clearly do not.

Dismissing ideas, no matter how far out they seem to you without experimenting, is not good science. I cannot remember any major innovation that was not called a crackpot idea by the people of the day.

Those are common crackpot fallacies about science. They just plain aren't true. First, a good experiment is based on pre-existing science. Second, good science is recognized by scientists virtually instantly. Common [wrong] examples often thrown around on that are Einstein's Relativity (it really was recognized quickly) and breaking the sound barrier (scientists did not think it was impossible).

I happened onto a website the other day that listed just about every technology in common use today and the reactions by the respected people of that time as they demeaned the technologies. It was enlightening.

I really would be curious to see it.

 

[vanesch]

I happened onto a website the other day that listed just about every technology in common use today and the reactions by the respected people of that time as they demeaned the technologies. It was enlightening.

People can make mistakes... in both directions. Here's a funny museum of great inventions that didn't work:
http://www.lhup.edu/~dsimanek/museum/unwork.htm

(now that I think of it, I think it was Russ who showed it to me first )

Read especially http://www.lhup.edu/~dsimanek/museum/impossible.htm

Now, I know we're not talking about perpetuum mobile here, but the ideas apply all the same.

 

[buffordboy23]

Here is a wikipedia link that discusses hydrogen fuel-enhancement. There are a lot of cited sources that discuss both positive and negative results.

http://en.wikipedia.org/wiki/Hydrogen_Fuel_Injection

 

[russ_watters]

I thought someone said earlier you could produce hydrogen via steam reforming of water. Part of the reason I didn't comment on that before is I hadn't heard of it and didn't know how it worked. The Wiki talks about steam reforming of methane. No doubt, you can increase the gasoline fuel efficiency of a car by adding a second ready-to-burn fuel to it. I guess the real question would be does the hydrogen provide more of a benefit than if you had just injected the methane itself into the engine. Methane is already quite a good fuel.

 

[RMForbes]

No, you clearly do not.

Please, instruct me to which concept I don't understand. At least, I am willing to admit when I don't get it exactly right. Or are you calling the guys at MIT crackpots too? This technology is far too important to be dismissed out of hand. We have the opportunity to drastically reduce emissions and end our countries dependence on foreign oil within just two to five years with a concentrated focused effort. But first people like you must stop ignoring the proof and help us work out the details. We have to start working together.

Those are common crackpot fallacies about science. They just plain aren't true. First, a good experiment is based on pre-existing science. Second, good science is recognized by scientists virtually instantly. Common [wrong] examples often thrown around on that are Einstein's Relativity (it really was recognized quickly) and breaking the sound barrier (scientists did not think it was impossible). I really would be curious to see it.

I understand what you are saying, but that is not exactly what I was taught in college. However, that was quite a few years ago now and things may have changed. I thought you first observed a process in nature then designed an experiment so that the processes can be revealed. We were taught that preconceptions usually taint the experiment. Designing a good experiment so that all is revealed, is actually an art form. I guess they now teach that there is no need to experiment if you are sure that the observed process can't possibly work.

http://www.null-hypothesis.co.uk/science/strange-but-true/item/invention_failure_never_work_disaster

I especially like the last one. "X-rays are a Hoax" Lord Kelvin ca. 1900

 

[vanesch]

Please, instruct me to which concept I don't understand.

I think Russ is pointing you to the Carnot efficiency of a thermal engine.

 

[Topher925]

I think Russ is pointing you to the Carnot efficiency of a thermal engine.

And this the Gibbs free energy for thermodynamic efficiency.

Can we get back to battery vs. hydrogen economy yet? I've seen this same conversation on at least 5 other forums.

http://coreygilmore.com/blog/wp-content/uploads/2007/08/beating_a_dead_horse.jpg

 

[RMForbes]

I think Russ is pointing you to the Carnot efficiency of a thermal engine.

While I agree that mathematical models are very useful but these two do not allow combustion speed to be a variable. Do you have a model where combustion speeds can be varied to show the effect on efficiency? This would be useful.

By the way, I just received an email from the CEO of Dutchman Enterprises. They have announced a partnership with Ford Motor Company to supply their HAFC (hydrogen assist fuel cell) and PICC (Pre Ignition Catalytic Converter) for their SUV and truck lines. At least someone is starting to take this seriously.

 

[russ_watters]

Please, instruct me to which concept I don't understand.

There are several, but the biggest are that you don't understand the different measures/types of efficiency and how they are arrived at. Ie, you have said you think there is a lot of combustion efficiency to be gained (when, in fact, it is already well in excess of 90%) and that there is a lot of thermodynamic efficiency to be gained (when, in fact, it has a real, hard limit of around 50%).

Or are you calling the guys at MIT crackpots too?

No. You are just reading things in these papers that aren't there.

This technology is far too important to be dismissed out of hand. We have the opportunity to drastically reduce emissions and end our countries dependence on foreign oil within just two to five years with a concentrated focused effort.

No, we don't.

But first people like you must stop ignoring the proof and help us work out the details. We have to start working together.

You need to learn the science that will tell you where the boundaries of technology are. The "proof" does not say what you think it says. I have explained quite succinctly (and you have completely ignored) what the papers actually say.

http://www.null-hypothesis.co.uk/science/strange-but-true/item/invention_failure_never_work_disaster

I especially like the last one. "X-rays are a Hoax" Lord Kelvin ca. 1900

Though that site is great fodder for crackpots, the vast majority of the quotes do not come from scientists and those that do are more about viability than possibility.

While I agree that mathematical models are very useful but these two do not allow combustion speed to be a variable. Do you have a model where combustion speeds can be varied to show the effect on efficiency? This would be useful.

An "ideal" model assumes perfection in everything including combustion speed. Thus it provides an upper boundary based on the assumption that every possible source of inefficiency, including improper timing of the combustion, can be overcome. By comparing the ideal to the actual, you can determine exactly how much room there is for technology to improve a thermodynamic device.

 

[Ivan Seeking]

RMForbes, no one here is being overly negative. These concepts are well understood and have been for over a century. The fact is that if this was truly a viable technology, there would be no need to argue for it.

Hydrogen is a great energy carrier - one that is relatively easy to make. But we do have to make it, so it is not an energy source. There is no mystery here.

 

[vanesch]

While I agree that mathematical models are very useful but these two do not allow combustion speed to be a variable. Do you have a model where combustion speeds can be varied to show the effect on efficiency? This would be useful.

The Carnot efficiency is a maximal efficiency that is theoretically possible in the conversion of heat into useful work - it doesn't have anything to do with a specific process. It is pretty fundamental. So given the combustion temperature of the ideal fuel mixture, and the temperature of the environment, one can easily calculate what is the maximal fraction of the thermal energy that could, by an imaginary engine of just any type, be converted in mechanical work.

The formula is extremely simple: that fraction is equal to 1 - T2/T1, where T2 is the temperature of the environment (in Kelvin), and T1 is the temperature of the combustion temperature (also in Kelvin).

For instance, consider boiling water at 100 centigrade, or 373 K, and the environment at 300K. Well, no matter what kind of machine you build, it will not be able to convert more than 1 - 300/373 = 19.5% of the heat that makes the water boil, into mechanical work.

If one goes in somewhat more detail of the specific process at hand, such as using the ideal gas law, and a compression, burning and expansion stage, one can get sometimes more detailed estimates of what is *in principle* possible.

In our example, if you have a genuine working steam engine which converts, say, 17% of the heat into work, then you have a pretty good machine, and you will only be able to improve it with about 2% absolulte, or something like 10% relative percents.

 

[RMForbes]

RMForbes, no one here is being overly negative. These concepts are well understood and have been for over a century. The fact is that if this was truly a viable technology, there would be no need to argue for it.

Hydrogen is a great energy carrier - one that is relatively easy to make. But we do have to make it, so it is not an energy source. There is no mystery here.

Again, I agree these processes have been well understood for almost as long as the internal combustion engine itself. So have steam reforming systems and alternative fuels. And yes, hydrogen is an excellent energy transfer agent, but again that is not what makes hydrogen enrichment work. Hydrogen reduces ignition lag and speeds combustion which allows the conversion more energy to torque instead of heat. Now, that sounds like an increase in efficiency to me but you all disagree. So can we say it increases gasolines octane?

 

[RMForbes]

I thought someone said earlier you could produce hydrogen via steam reforming of water. Part of the reason I didn't comment on that before is I hadn't heard of it and didn't know how it worked. The Wiki talks about steam reforming of methane. No doubt, you can increase the gasoline fuel efficiency of a car by adding a second ready-to-burn fuel to it. I guess the real question would be does the hydrogen provide more of a benefit than if you had just injected the methane itself into the engine. Methane is already quite a good fuel.

I was referring to an article I read on a alternative fuels website. You misunderstood my point. Here is a short quote to make things more clear;

”The main problem with ethanol is that the majority of engines on the road today are not designed for it. The exception is the Saab 9-5 Biopower engine, which IS optimized for ethanol. It outperforms gasoline, getting 20% more power, 16% greater torque, and 10% better mileage. The Lotus Exige 265E “Flexi” gets 45 more horse power on E85 than it gets on gasoline. Within the next two years, Suzuki, Ford, GM and numerous other car makers will introduce engines which exploit the advantages of ethanol, for its high octane and compatibility with water. Our system of blending 15% gasoline into ethanol is not necessary. Ethanol can be denatured without using gasoline. That was how politicians created an incentive for oil companies to distribute ethanol, by giving them a 51 cent per gallon tax credit to blend it with gasoline. Problem is, ethanol performs better when it’s mixed with water rather than gasoline. This is called hydrous ethanol. Nothing new. In the 1920's, the model A Ford cars and trucks ran on 165 proof ethanol, 17.5% water and 82.5% ethanol. Recently, a Pratt Community College engine testing team lead by instructor Greg Bacon, mixed 20% water with pure ethanol, and efficiency in the combustion chamber doubled. When the ethanol explodes, the water instantly turns into additional power in the form of steam and also provides hydrogen and oxygen inside the cylinder. Next year, Ford is introducing the EcoBoost engine, which may also have advanced ethanol technology that doubles efficiency. Brazil has been using 4% hydrous ethanol for years. They laughed at us when we started mixing ethanol with gasoline. Phil Ratte, Mechanical Engineer, BME University of Minnesota said: “From 1981 to 1989, I worked with Herb Hansen, who had been an engineer on a WW II submarine, and a former captain of a nuclear submarine. We developed two prototype cars, a Ford Pinto Station Wagon and a Mitsubishi Sedan, that ran as well on 65 proof ethanol (2/3 water and 1/3 ethanol) as they did on unleaded regular gas.” What is the one thing that the big oil companies fear the most? Water. The State of Louisiana now has an experimental hydrous ethanol program that may also be replicated in other states. Dongfeng, a major Chinese auto maker is introducing a car this year, with a slightly modified fuel system, that runs on 65% ethanol and 35% water. They claim hydrogen is formed. Toyota also has a similar hydrous ethanol prototype that produces on board hydrogen. The BTU argument that ethanol is inferior to diesel and gasoline is not valid. Since ethanol is water soluble and high octane, with advanced engine technology, it can outperform gasoline 2 to 1 or better. Major automakers are scheduled to produce smaller, lighter, high compression, turbocharged ethanol optimized engines that are far more efficient than current gasoline and diesel engines. And the fuel will be cheaper. If you prefer an ethanol powered fuel cell, the Swift Direct Proton Fuel Cell developed by Purdue University’s Research Park in West Lafayette, Indiana is about $2,000, only 1/10 the price of a hydrogen fuel cell. Maybe that’s why Toyota is building ethanol plants in Brazil, and GM is investing in ethanol development in the U. S…They must know something we don’t know about ethanol. “

 

[Topher925]

The BTU argument that ethanol is inferior to diesel and gasoline is not valid. Since ethanol is water soluble and high octane, with advanced engine technology, it can outperform gasoline 2 to 1 or better.

How can the BTU argument not be valid? So because a substance A has 85% of the internal energy of substance B, substance A can produce twice the energy as B because it has a higher octane rating? Do you even know what an octane rating (R+M test) means?

RMF, you really need to stop posting your propaganda and go read some books. Ethanol is not a viable energy source, its actually a very poor one. The only reason E85 and all its hype was created was because the US had a huge surplus of corn. Thats it. Not because it makes some "super duper" fuel source.

 

[RMForbes]

How can the BTU argument not be valid? So because a substance A has 85% of the internal energy of substance B, substance A can produce twice the energy as B because it has a higher octane rating? Do you even know what an octane rating (R+M test) means?

RMF, you really need to stop posting your propaganda and go read some books. Ethanol is not a viable energy source, its actually a very poor one. The only reason E85 and all its hype was created was because the US had a huge surplus of corn. Thats it. Not because it makes some "super duper" fuel source.

It's not my propaganda! This is a paragraph that I copied from a E-zine on the Green Fuels website. I made no value judgement on it, you did.

 

[Topher925]

It's not my propaganda! This is a paragraph that I copied from a E-zine on the Green Fuels website. I made no value judgement on it, you did.

Oh ok, it must be true then.

 

[RMForbes]

Oh ok, it must be true then.

I don't know. But they did give references that you could check out without much effort. Do you know how to do a Google search?

 

[Ivan Seeking]

Again, I agree these processes have been well understood for almost as long as the internal combustion engine itself. So have steam reforming systems and alternative fuels. And yes, hydrogen is an excellent energy transfer agent, but again that is not what makes hydrogen enrichment work. Hydrogen reduces ignition lag and speeds combustion which allows the conversion more energy to torque instead of heat. Now, that sounds like an increase in efficiency to me but you all disagree. So can we say it increases gasolines octane?

You keep missing the point. Let's assume hydrogen enrichment works, which it probably does. This does not speak to the complete efficiency of the process. There are more losses associated with producing the hydrogen than you will get back through increased efficiencies. The problem with hydrogen is producing the stuff.

Also, you can have whatever octane rating that you wish, but in the end you can't beat conservation of energy.

 

[Ivan Seeking]

As for Green Fuels, they make a lot of funny claims. For example, here they are discussing a particular interest of mine - biodiesel from algae:

The Vertigro Bio Reactor System has been designed to avoid both problems. Algae is grown within plastic bubbles hanging from racks in a greenhouse. Vertigro is a joint venture by and Global Green Solutions, a giant with offices in El Paso, Vancouver, London, Brussels and Johannesburg, and Valcent Products of Texas. During a 90-day continual production test, algae was being harvested at an average of one gram (dry weight) per liter, which the company estimates would equate to 33,000 gallons of algae oil per acre per year. Such an output is a third more than a pond system could produce, the team estimates.

http://www.greenfuelsforecast.com/ArticleDetails.php?articleID=481

It has been calculated that there is a net upper limit of about 10,000 gallons per acre-year based on the available energy input, which is absolute. The claim of 33,000 gallons is ridiculous.

 

[buffordboy23]

Hydrogen enrichment does work for lean engine operation. This is a condition when there is more air than at stoichiometric. Hydrogen makes the air/fuel mixture more homogeneous, which permits a more efficient combustion of gasoline during such conditions and smooths out the large temperature gradients associated with localized fuel charges. By having more air in the combustion cylinder, more work on the piston can be done, especially at higher compression ratios, because less heat from combustion is transferred to cylinder walls.

As for hydrogen enrichment at stoichiometric conditions, this is extremely questionable. I haven't seen any peer-reviewed studies that address this specific question, so this suggests that it is not a viable option. A while ago, I remember reading an article that looked at this aspect during a combustion simulation. If I recall correctly, the thermal efficiency increased by 2% but I forget what the assumed hydrogen flow rate was during the simulation. This efficiency improvement does not appear to compensate for the energy needs to produce hydrogen. If I find the article, I will post the data.

Although your argument makes sense Ivan Seeking, I am not fully convinced. The reason why is because hydrogen addition will likely change the combustion products, which could affect sensor data. If sensor data is affected is such a way, then it may be possible to "trick" your car into running lean, which may increase fuel economy but yet could be damaging in the long-term to your engine. For example, if hydrogen addition causes more gasoline to be combusted, which would be no more than 1% since most fuel is combusted anyways, then there is a reduction of free oxygen in the exhaust products. As a consequence, the O2 sensor would measure that the car is running "rich" for some throttle position, which could cause the ECU to shorten the fuel pulse-width to obtain the required free-oxygen products. Thus the car is now operating lean, and it could be possible to obtain an improvement in fuel economy. This is a hypothesis that I plan to test in the upcoming months by using an OBD-II interface and laptop computer to measure sensor data.

In regards to the hydrogen economy, I see that it will not be feasible for a long time, since many breakthroughs are needed, like storage, production, infrastructure, etc. What does make sense to me is that gasoline-hydrogen automobile hybrids, with the appropriate engine modifications for lean operation and machinery for producing sufficient quantities of hydrogen on-board, could become common in the near future. Such vehicles would have improved fuel economy and reduced emissions.

 

[mheslep]

As for Green Fuels, they make a lot of funny claims. For example, here they are discussing a particular interest of mine - biodiesel from algae:


http://www.greenfuelsforecast.com/ArticleDetails.php?articleID=481

It has been calculated that there is a net upper limit of about 10,000 gallons per acre-year based on the available energy input, which is absolute. The claim of 33,000 gallons is ridiculous.

Unless they went vertical? Probably still ridiculous.

 

[RMForbes]

You keep missing the point. Let's assume hydrogen enrichment works, which it probably does. This does not speak to the complete efficiency of the process. There are more losses associated with producing the hydrogen than you will get back through increased efficiencies. The problem with hydrogen is producing the stuff.

Also, you can have whatever octane rating that you wish, but in the end you can't beat conservation of energy.

I don't think I'm the one missing the point, I think you guys are trying to pull a Sarah Palin on me. (Half joking) Where we are having an issue is how much hydrogen it takes to maintain lean engine operation. You like most of the researchers (until quite recently) have ASSUMED it would require a rather large amount. That is not the case; those of us that have been experimenting have found positive results with as little as 3 to 4 grams/hour. That amount of hydrogen can easily be produced by a 350 watt device. But if you insist that more hydrogen would be required, try using the waste heat from the exhaust to generate steam and then run that through a magnetic field or around charged plates to disassociate the hydrogen and oxygen gases. Much more hydrogen can be produced this way by using waste heat energy.

 

[Topher925]

Although your argument makes sense Ivan Seeking, I am not fully convinced. The reason why is because hydrogen addition will likely change the combustion products, which could affect sensor data. If sensor data is affected is such a way, then it may be possible to "trick" your car into running lean, which may increase fuel economy but yet could be damaging in the long-term to your engine. For example, if hydrogen addition causes more gasoline to be combusted, which would be no more than 1% since most fuel is combusted anyways, then there is a reduction of free oxygen in the exhaust products. As a consequence, the O2 sensor would measure that the car is running "rich" for some throttle position, which could cause the ECU to shorten the fuel pulse-width to obtain the required free-oxygen products. Thus the car is now operating lean, and it could be possible to obtain an improvement in fuel economy. This is a hypothesis that I plan to test in the upcoming months by using an OBD-II interface and laptop computer to measure sensor data.

This is actually the case for most hydrogen assisted do it yer-self kits. Not only does the ECU lean the engine due to bad sensor data but most kits actually come with a unit to emulate the air sensor past the throttle body causing the ECU to run the engine lean also. I haven't seen any results of this lean operating condition but I am sure that as more garage scientists put these things in their cars you will start seeing the longer term affects. Not to mention the affects of the metals in the engine becoming hydrides.

 

[RMForbes]

This is actually the case for most hydrogen assisted do it yer-self kits. Not only does the ECU lean the engine due to bad sensor data but most kits actually come with a unit to emulate the air sensor past the throttle body causing the ECU to run the engine lean also. I haven't seen any results of this lean operating condition but I am sure that as more garage scientists put these things in their cars you will start seeing the longer term affects. Not to mention the affects of the metals in the engine becoming hydrides.

Wow, I thought they are storing H2 in metal tanks at 10k psi. Don't you think we should warn them before the metal turns to mush?

 

[Topher925]

Wow, I thought they are storing H2 in metal tanks at 10k psi. Don't you think we should warn them before the metal turns to mush?

The metal doesn't turn to "mush" the modules of elasticity still remains the same. The material just becomes much more brittle and less ductile.

 

[RMForbes]

The metal doesn't turn to "mush" the modules of elasticity still remains the same. The material just becomes much more brittle and less ductile.

The engine is already exposed to hydrogen during combustion, adding a little more will not effect any metal parts. To suggest it will is ridiculous.

 

[mheslep]

Wow, I thought they are storing H2 in metal tanks at 10k psi. Don't you think we should warn them before the metal turns to mush?

No they don't. Most tanks are 3K or 5K PSI, with a few 10k PSI tanks coming out now. The higher pressure tanks have sophisticated non metallic liners to prevent H2 permeating into the metal.

See issue on storage and transport of H2 here:
http://www.efcf.com/reports/E08.pdf

 

[mheslep]

The engine is already exposed to hydrogen during combustion, adding a little more will not effect any metal parts. To suggest it will is ridiculous.

I believe you want to check that too. I assume you are referring to some intermediate product of combustion that produces atomic or molecular hydrogen? If that exists at all, the amount of H2 in the piston from the suggested enrichment scheme (10%?) would be many orders or magnitude greater than any trace H2 found in standard hydrocarbon reactants or products.

Also see http://mechanicalplating.com/hydrogen.htm

 

[RMForbes]

I believe you want to check that too. I assume you are referring to some intermediate product of combustion that produces atomic or molecular hydrogen? If that exists at all, the amount of H2 in the piston from the suggested enrichment scheme (10%?) would be many orders or magnitude greater than any trace H2 found in standard hydrocarbon reactants or products.

Also see http://mechanicalplating.com/hydrogen.htm

Even if the levels needed are that high, which is not the case, all the hydrogen is consumed at the beginning of combustion. There is no chance for hydrogen to react with the metal anywhere.

 

[mheslep]

Even if the levels needed are that high, which is not the case, all the hydrogen is consumed at the beginning of combustion. There is no chance for hydrogen to react with the metal anywhere.

That statement doesn't make any sense. Of course the hydrogen is consumed by combustion, prior to that in a four stroke engine, during both he intake and compression strokes the air-fuel mixture is in contact with the cylinder.
http://media-2.web.britannica.com/eb-media/72/93572-034-26C16785.jpg

 

[RMForbes]

That statement doesn't make any sense. Of course the hydrogen is consumed by combustion, prior to that in a four stroke engine, during both he intake and compression strokes the air-fuel mixture is in contact with the cylinder.
http://media-2.web.britannica.com/eb-media/72/93572-034-26C16785.jpg

So you are saying that the hydrogen will be able to chemically alter the metal as it flows through the intake at high speed before it combusts. We are talking milli-seconds here, not weeks or months of storage at high pressures.

 

[mheslep]

So you are saying that the hydrogen will be able to chemically alter the metal as it flows through the intake at high speed before it combusts. We are talking milli-seconds here, not weeks or months of storage at high pressures.

The cylinder is exposed to hydrogen roughly half the time the engine is running, regardless of the cycle time, and at high temperature which accelerates embrittlement. I don't think embrittlement qualifies as chemical reaction; http://en.wikipedia.org/wiki/Hydrogen_embrittlement#Process" the process is due to the formation of molecular hydrogen inside flaws in the metal lattice, worsening them. Since all gas is removed during the evacuation stroke perhaps this slows the diffusion of H into the metal lattice vs the rate seen in a static container, but a same time evacuation cycle is not going to pull all of the atoms back out of the lattice.

No doubt some coating or lubricant can help protect the cylinder on an engine designed for H2, but I think it likely unprepared gasoline engines are likely to see damage with extensive H2 burning.