Is Hydrogen Economy Viable Without Fusion Energy?

[mheslep]

...I've been musing that perhaps a solar/wind/grid based local roadside H2 station might start to make sense.

It turns out that the paper by Bossel "www.efcf.com/reports/E21.pdf"[/URL], 2006, dedicated a section to just this subject so I'm revisiting this post to compare. Bossel demolishes transportation of H2 and then logically turns to on-site production:
[QUOTE=Bossel 2006]I. On-Site Generation of Hydrogen One option for providing hydrogen at filling stations and dispersed depots is on-site generation of the gas by electrolysis. Again, the energy needed to generate and compress hydrogen by this scheme is compared to the HHV energy content of the hydrogen transferred to cars. Natural gas reforming is not a sustainable solution and thus not considered for the reasons stated earlier...[/QUOTE]
Vanesch will like the next:
[QUOTE=Bossel 2006]Consider a filling station now pumping [B]60 000 L[/B][15850 gallons] of fuel (gasoline or diesel) into 1000 cars, trucks, or buses per day. This number is typical for service areas along [B]European[/B] freeways. In most parts of the [B]United States, many smaller[/B] filling stations are located roadside at freeway exits.[/QUOTE]60000L/day! Must have an on-site refinery! I had used 2000g/day for our 'smaller' stations.

Then on the efficiency of H2 vs gas fueled ICS vehicles, Bossel downrates my 3x efficiency advantage estimate to 1.5:
[QUOTE=Bossel 2006]...However, hydrogen vehicles are assumed to have a 1.5 times higher tank-to-wheel efficiency than IC engine cars [29]. [B]The frequently cited number of 2.5 cannot be justified any longer[/B] in light of the high efficiency of diesel or hybrid vehicles. In fact, the well-to-wheel studies of 2002 [8], [9] are based on lower heating values, optimistic assumptions of fuel cells, and disregard of the efficiency potentials of
diesel engines and hybrid systems. The shortcoming of LHV analyses is discussed in [30]. Furthermore, more recent well-to-wheel studies appropriately based on the higher heating values [10] do not identify hydrogen-fuelcell cars as the best transportation option. In fact, the efficiency of all-electric cars is three times better than for hydrogen-fuel-cell vehicles [31].[/QUOTE]I have not run down these references yet, no doubt some mention of variable displacement ICE and the like. Bossel does use the term 'potential' regarding high efficiency ICE, but point taken.

More:
[QUOTE=Bossel, 2006]Under the favorable assumption of a 1.5 advantage of hydrogen versus gasoline, 60 000 liters of fuel will be replaced by 12 000 kg of hydrogen per day. The
electrolyzer efficiency may be 75%. Also, losses occur in the ac–dc power conversion. Making 12 000 kg of hydrogen per day by electrolysis requires 25 MW of continuous power and 108 000 liters of water must be pumped and demineralized. Compression power is needed for storing the hydrogen to 10 MPa and for transfer at 40 MPa to vehicle tanks at 35 MPa. In all, to generate and store 12 000 kg of hydrogen per day, the filling station must be supplied with continuous electric power of about [B]28 MW[/B]. There are many sites in arid regions where neither the electricity nor the water is available for hydrogen production.[/QUOTE]My assumptions (vs Bossel): 3x better vehicle efficiency (vs 1.5), 90% MIT/Nocera electrolysis (vs 75%), no AC/DC conversion of DC on-site solar (vs 95%). Using my assumptions we have a 10.3MW (Euro size) fuel station. I only quarrel with his 1.5x vs 3x assumption at the front end: the numbers of Bossels on highly efficient ICE are beside the point, the 60000L/day figure must be [U]today's[/U] consumption figure using '1x' cars of ~30mi/gal, not tomorrows better ICE, so the H2 converted fuel station, still serving '1000 cars', 90mi/gal equivalent, would only have to pump the equivalent of only 20000L, not 40000L. So Bossel's grid driven traditional electrolysis station should actually require 14MW.

Regardless, the large power connection drives home the point about the difficulty of connecting to the grid further adds to the case for doing solar on-site. I hadn't considered the water load which is substantial.

 

[Kasper_NYC]

This article is really interesting:

The Economics of Small to Medium Liquid Hydrogen Facilities

http://www.rmwsolutions.net/pub3.pdf

Otherwise I don't see easy at all to keep the hydrogen liquefied in a tank in ours cars... and just compressed doesn't make too much sense to me either. I guess we are going to keep seeing hydrocarbons in our car for long more time.

From this Document: http://www.dotynmr.com/PDF/Doty_H2Price.pdf

"... A common 120-gallon compressed-air tank, which can store 0.57 kg of hydrogen at 15 atm., costs $730 [31]. At $1300/kg, this is 85 times as expensive as the diesel tank per energy storage, and it is 40 times more massive and over 200 times larger. Fifty (very large) 3000 psi aluminum scuba tanks could provide 10 kg of H2 storage for under $14,000 and only 750 kg [32]. Pricing data from the high-volume production of these tanks suggest high-volume production of 5000-10,000 psi tanks for storage of 3-8 kg of H2 might cost $600/kg of H2, which is about 30% less than suggested in an earlier study..."

Best.

 

[Topher925]

You have to look at the big picture when it comes to hydrogen storage. The tank itself might be cheaper for gasoline or diesel but you also need to include the fuel delivery system, including filters and a pump that operates at 100% output when ever the engine is running. Fuel pumps are known to fail along with being very inefficient and on many models fuel filters need replacing. A compressed tank of H2 should be a one time purchase with little or no maintenance through out its life. And while the tank may be heavier, the fuel it is carrying is definitely not. I don't have time to crunch the numbers but 50kwh of H2 will weigh a lot less than 50kwh of gasoline, including the tanks.

Honda has already shown that using compressed H2 can be done practically. Although a better method of storage is certainly welcome.

 

[mheslep]

You have to look at the big picture when it comes to hydrogen storage.

We have been.

And while the tank may be heavier, the fuel it is carrying is definitely not. I don't have time to crunch the numbers but 50kwh of H2 will weigh a lot less than 50kwh of gasoline, including the tanks.

No, in a road vehicle using steel tanks the H2 system will weigh a little more. Carbon fiber tanks can remedy that but they are $$$. More importantly, the compressed H2 tank volume is several times greater regardless of material, at least 3X at 10,000PSI assuming the vehicle needs only 1/3 the energy; if you want the same energy content as a tank of gasoline its ~7X more volume, i.e, a fuel tank with wheels.

Honda has already shown that using compressed H2 can be done practically. Although a better method of storage is certainly welcome.

I'd say they've shown it can be done, period. Honda's cost to make the car is >$200k last I read. For reasons discussed above, one needs to stay close to the one or two H2 stations in your area if you have such a car, and the stations are not practical either. I also suspect the long term reliability of the fuel cell and its operation in cold climates is still an open question.

 

[gmax137]

Well, you might be surprised, but most french nuclear power stations can follow load, they are not only working in baseload. They can ramp at 5% of nominal power per minute, as long as they stay between 30% and 100% of nominal capacity (below 30%, there are problems with Xe poisoning). They can even handle up to 10% "immediate" load change from their working point.

The US nuclear units were also designed for daily load follow. They aren't operated that way, because once built, they provide the cheapest source of power. The fuel is almost free, compared to oil, gas, or even coal. So the power companies minimize their cost by running the nuclear units at full power, 24 x 7.

 

[RMForbes]

Why store hydrogen? Steam Reforming systems and even simple electrolysis systems are already available that can produce adequate hydrogen on-demand. Most of the energy consumption to produce compressed hydrogen gas is used to separate, purify and compress the gas for storage. If the goal is to produce a clean more efficient vehicle there is no need to separate the hydrogen out. Just produce it on board.

 

[Mech_Engineer]

Why store hydrogen? Steam Reforming systems and even simple electrolysis systems are already available that can produce adequate hydrogen on-demand. Most of the energy consumption to produce compressed hydrogen gas is used to separate, purify and compress the gas for storage. If the goal is to produce a clean more efficient vehicle there is no need to separate the hydrogen out. Just produce it on board.

Perhaps you could tell us all where the energy comes from to produce the hydrogen on-board in the first place?

Be warned that if you say "from burning some of the hydrogen on-board" I may end up having a slight aneurysm.

 

[mgb_phys]

Why store hydrogen?...If the goal is to produce a clean more efficient vehicle there is no need to separate the hydrogen out.

The goal is also to use hydrogen as a storage and transport mechanism so that energy generated a long way from the customer, geothermal in Hawaii or solar in Arizona, or intermittently, such as wind, can be used economically. Hydrogen is really more of a battery than a fuel.

 

[mheslep]

Why store hydrogen? ...

Reforming CNG etc presupposes that CNG is your energy carrier. The idea behind the 'H economy' is that we get off fossil fuels and in that case how do we move energy around? It turns out fossil fuels are great energy carriers in BTU/lb and BTU/gal. Certainly electric power is a big part of that answer, but then 1) how do you handle variable electric power from wind, solar, etc., and 2) how do you store energy on anything disconnected from the grid e.g. vehicles.? As Greenspan said, the electric utilities 'have no inventory'.

Most of the posts in this thread discuss proposals and problems w/ either 1) or 2)

 

[Mech_Engineer]

It turns out fossil fuels are great energy carriers in BTU/lb and BTU/gal.

More important than the fact that fossil fuels have large amounts of energy per volume, is that the energy has already been captured and stored in them. If we manufacture Hydrogen for energy storage and transport purposes, we have to get that energy from somewhere.

Hydrogen : Oil :: Empty Gas Tank : Full Gas Tank

Hydrogen can be used to store and ship energy yes, but that energy has to be acquired and put into the Hydrogen first.

 

[mheslep]

More important than the fact that fossil fuels have large amounts of energy per volume, is that the energy has already been captured and stored in them. If we manufacture Hydrogen for energy storage and transport purposes, we have to get that energy from somewhere.

Hydrogen : Oil :: Empty Gas Tank : Full Gas Tank

Hydrogen can be used to store and ship energy yes, but that energy has to be acquired and put into the Hydrogen first.

Yeah we need a sticky or something to say H2 is carrier, it has to be produced just like a battery has to be charged, then we just say that is a given and get on to the practical problem of how best to store and dispatch energy in a world where fossil fuel is unusable or too expensive.

 

[RMForbes]

First of all, I don't want anyone to have an aneurysm. Waste heat from the exhaust is a perfect source for energy recycling. Steam reformers use the heat energy directly to generate hydrogen and convert existing fuels to a cleaner burning more efficient fuel. TEG’s can be used to convert the waste heat energy into electricity. Some of this electrical energy can be used to produce hydrogen and oxygen gas through electrolysis. With millions of internal combustion engines already in use, doesn’t it make more sense to focus on modifying those first, before we create a whole new technology that requires a huge infrastructure that will take several years to develop. Don’t get me wrong, I am not saying we should stop developing hydrogen fuel cells. Just that there are huge gains that can be made much faster by increasing fuel economy on these existing engines while we are producing and developing new technologies.

Yes, hydrogen can be used as an energy storage and transfer mechanism but when injected into an internal combustion engine the combustion characteristics are changed. “Adding small amounts of hydrogen to gasoline produced efficient lean operation by increasing the apparent flame speed and reducing ignition lag” (ref 1977 NASA study). The stored energy of the hydrogen is not the mechanism that is responsible for this increase in efficiency. Hydrogen ignites much easier and burns many times faster than the gasoline or diesel. As it burns it ignites the primary fuel much faster and completely. The resulting combustion starts sooner and burns faster, so all the fuel is consumed long before the end of the power stroke. This is no unburnt fuel to be recycled by the EGR system or incinerated by the catalytic converter. The piston has more time and travel to absorb the energy of the resulting pressure wave and converting this energy into torque. Considerably less energy is lost as heat out the exhaust. By utilizing closed loop control systems and steam fuel reforming systems fuel efficiencies can be optimized by controlling the timing and concentrating full combustion to just a few degrees after top dead center of the power stroke.

 

[Coin]

First of all, I don't anyone to have an aneurysm. Waste heat from the exhaust is a perfect source for energy recycling...

So... this doesn't seem to really be addressing the idea of hydrogen at all? Hydrogen is being proposed as a method of getting energy into car engines, in response you are proposing a generalized method for making car engines more efficient period. While maybe more efficient engines are desirable, surely this is orthogonal to whether the engine is fueled by fossil fuels, hydrogen, or batteries...

Moreover if there is a method for making engines more efficient, I do not think the car companies need any specific extra inducement to use it? Better fuel efficiency is already not only a strong selling point for cars, but mandated by current law and stricter laws to come...

Yes, hydrogen can be used as an energy storage and transfer mechanism but when injected into an internal combustion engine the combustion characteristics are changed. “Adding small amounts of hydrogen to gasoline produced efficient lean operation by increasing the apparent flame speed and reducing ignition lag” (ref 1977 NASA study). The stored energy of the hydrogen is not the mechanism that is responsible for this increase in efficiency. Hydrogen ignites much easier and burns many times faster than the gasoline or diesel. As it burns it ignites the primary fuel much faster and completely. The resulting combustion starts sooner and burns faster, so all the fuel is consumed long before the end of the power stroke. This is no unburnt fuel to be recycled by the EGR system or incinerated by the catalytic converter. The piston has more time and travel to absorb the energy of the resulting pressure wave and converted to torque. Considerably less energy is lost as heat out the exhaust. By utilizing closed loop control systems and steam fuel reforming systems fuel efficiencies can be optimized by controlling the timing and concentrating full combustion to just a few degrees after top dead center of the power stroke.

So I'm not sure I understand what you're suggesting... I think hydrogen is not usually used in an internal combustion engine, my understanding was that hydrogen cars run on fuel cells. I know internal-combustion cars that use hydrogen instead of gasoline have been produced but I think they're mostly gimmicks.

However it sounds like what you're suggesting is a fossil fuel engine that also has a supply of hydrogen, it injects the hydrogen into the fossil fuels it burns, and this increases the performance above and beyond what a fossil fuel or hydrogen engine would be able to achieve on its own? Is this correct? Interesting...

 

[mheslep]

H2 boosting / electrolysis has been debunked on another thread:
https://www.physicsforums.com/showpost.php?p=1830195&postcount=12
https://www.physicsforums.com/showthread.php?p=1830195&highlight=waste#post1830195

 

[russ_watters]

So... this doesn't seem to really be addressing the idea of hydrogen at all? Hydrogen is being proposed as a method of getting energy into car engines, in response you are proposing a generalized method for making car engines more efficient period. While maybe more efficient engines are desirable, surely this is orthogonal to whether the engine is fueled by fossil fuels, hydrogen, or batteries...

Yes, and due to current technological hurdles, hydrogen production is not the most effective way to use that waste heat. Probably the best is an aft-end boiler to drive a turbine.

Of course, the turbine could turn a generator to make hydrogen, but it would probably be better to either connect the tubine to the drive shaft to boost mechanical power or produce energy to be stored in batteries, more like a conventional hybrid.

 

[russ_watters]

Yes, hydrogen can be used as an energy storage and transfer mechanism but when injected into an internal combustion engine the combustion characteristics are changed. “Adding small amounts of hydrogen to gasoline produced efficient lean operation by increasing the apparent flame speed and reducing ignition lag” (ref 1977 NASA study).

We've discussed that study before. It claims a 9% improvement in fuel efficiency with hydrogen injection, which works out to (iirc) roughly 3x more energy than is contained in the hydrogen. But that is not enough to cover the energy required to produce the hydrogen.

 

[RMForbes]

"However it sounds like what you're suggesting is a fossil fuel engine that also has a supply of hydrogen, it injects the hydrogen into the fossil fuels it burns, and this increases the performance above and beyond what a fossil fuel or hydrogen engine would be able to achieve on its own? Is this correct? Interesting... "

Yes, there are systems that are currently available like systems that use a modified catalytic converter to capture waste energy from the exhaust to reform the fuel just before intake. By reforming the fuel in this way fuel economy is greatly increased. Hydrogen is produced in much higher concentrations than with electrolysis plus the primary fuel is also reduced to smaller components so they ignite easier and burn faster. Much closer to optimum fuel economies are being realized. While most of these systems currently operate on gasoline, alternative fuels have been shown to work even better. Fuels that mix well with water actually work the best, which also has the added advantage of not requiring an additional storage/delivery system for water. It’s already in the fuel.
.

 

[misgfool]

Today's New York Times (http://www.nytimes.com/2008/08/27/business/27grid.html) had an interesting article about wind power that goes along the lines of mheslep's comment. Many wind farms have to shut down when the wind is too strong because they're generating too much energy for the power grid.

Here in Europe the wind monstrosities have to shut down at high wind speeds to prevent them from harming themselves. The new 6 MW designs have blade length of up to 90 m and peak height is almost 200 m!

 

[RMForbes]

We've discussed that study before. It claims a 9% improvement in fuel efficiency with hydrogen injection, which works out to (iirc) roughly 3x more energy than is contained in the hydrogen. But that is not enough to cover the energy required to produce the hydrogen.

Sorry I missed the discussion. I just reread the study again and I don't see where they concluded that more energy was required to produce the hydrogen than was gained in fuel efficiency. I did see where they found that up to 37% less energy was lost out the exhaust.

 

[russ_watters]

That sentence was my conclusion using some rough calculations of the energy efficiency of the processes. The 9% efficiency improvement was using bottled hydrogen, not hydrogen generated by the car.

1 Joule of hydrogen acts like 3 joules when injected... but then the car only uses it at about 30% efficiency, the alternator 90% efficiency, and the electrolysis device only 60% efficiency. Multiplied together, that's a 16% efficient cycle. 16*3= 48% efficient. In other words, even with the efficiency increase of the engine, producing 1 J of hydrogen requires 2 J of gas.

 

[RMForbes]

That sentence was my conclusion using some rough calculations of the energy efficiency of the processes. The 9% efficiency improvement was using bottled hydrogen, not hydrogen generated by the car.

1 Joule of hydrogen acts like 3 joules when injected... but then the car only uses it at about 30% efficiency, the alternator 90% efficiency, and the electrolysis device only 60% efficiency. Multiplied together, that's a 16% efficient cycle. 16*3= 48% efficient. In other words, even with the efficiency increase of the engine, producing 1 J of hydrogen requires 2 J of gas.

While that may be the case, the study clearly showed that energy input was not the mechanism that created the increase in efficiency. The gain was made with less system loss on the back end. Less energy was lost out the exhaust, more energy from the combustion is captured by the piston and converted to torque. By reducing ignition lag and increasing flame speed the energy of combustion is concentrated closer to the beginning of the power stroke so the piston has more time and travel to convert more of this energy. Since nearly 85% of the energy produced by combustion is lost as heat out the exhaust, there is plenty of room for efficiency improvement here.

 

[mheslep]

That sentence was my conclusion using some rough calculations of the energy efficiency of the processes. The 9% efficiency improvement was using bottled hydrogen, not hydrogen generated by the car.

1 Joule of hydrogen acts like 3 joules when injected...

That much? Surprising. I was under the impression that the burn was already highly efficient and most of the loss was in the nature of the mechanically driven heat engine regardless of burn efficiency.

but then the car only uses it at about 30% efficiency, the alternator 90% efficiency, and the electrolysis device only 60% efficiency. Multiplied together, that's a 16% efficient cycle. 16*3= 48% efficient. In other words, even with the efficiency increase of the engine, producing 1 J of hydrogen requires 2 J of gas.

So that rules out on board generation but what if you bottle H2 locally? For instance: Some renewable source of energy, say solar -> electrolysis 75% (maybe 90 soon) -> compression to store 90% = 66% (81%); or cracking of methane and compress. From there I think an economic analysis is needed to justify the boosted gasoline-H2 efficiency.

 

[Topher925]

Propane makes a much better fuel additive then hydrogen. In ideal combustion, the hydrogen will never even be oxidized do to its hire ignition temperature.

Your efficiency doesn't come from burning hydrogen it comes from displacing nitrogen with oxygen. This means less losses at the throttle and less losses due to compression and heating of nitrogen gas which just absorbs heat.

 

[RMForbes]

Propane makes a much better fuel additive then hydrogen. In ideal combustion, the hydrogen will never even be oxidized do to its hire ignition temperature.

Your efficiency doesn't come from burning hydrogen it comes from displacing nitrogen with oxygen. This means less losses at the throttle and less losses due to compression and heating of nitrogen gas which just absorbs heat.

Actually propane is a better primary fuel source. It is already completely gaseous so it does not need extra time to be vaporized like liquid fuels. But nothing ignites easier or burns faster than hydrogen.. Hydrogen is the smallest, lightest, and most reactive element that is why it is at the top left side of the periodic chart of the elements. Hydrogen ignites easier and burns many times faster than any other element. Adding hydrogen to an internal combustion engine is like adding charcoal lighter fluid to your Bar-B-Q, it gets things started faster. This was the conclusion of the JPL and NASA studies from the 70's. Both studies concluded that adding small amounts of hydrogen reduces ignition lag and increases flame speed, which supports much leaner air/fuel mixtures. It does not have anything to do with adding or transferring additional energy to the combustion, the Second Law of Thermodynamics is therefore not being violated.

Without hydrogen injection gasoline is ignited by the spark plug several degrees before the beginning of the combustion/power stroke and is still burning when the piston reaches the bottom of this power stroke. The remaining unburnt fuel is then forced through the exhaust system to the EGR system to be recycled or to the catalytic converter to be incinerated (wasted). With hydrogen injection the combustion is much faster because the hydrogen burns quickly igniting the primary fuel from all sides at once. When proper engine timing and fuel mixture adjustments are made, the peak of the resulting pressure wave created by the combustion is higher (more energetic) and closer to the beginning of the power stroke because of this faster complete burn. Since most of the energy is released when the piston is near the top of the power stroke, more energy is able to be absorbed by the piston and converted to torque. Less energy is lost as heat through the exhaust. There is no unburnt fuel to be recycled by the EGR system or incinerated by the catalytic converter. A faster more efficient burn and less lost energy out the exhaust pipe means more power is converted to torque for power to the wheels, from equal amounts of energy input. This increase in over all system efficiency is the mechanism that creates increased fuel economy.

What the NASA study does show conclusively is that hydrogen injection does reduce ignition lag and increases flame speeds. Therefore, designing systems for optimum fuel efficiency requires the energy released from the combustion to be focused at the very beginning of the power stroke, where the piston has the maximum time and travel to absorb the energy of the resulting pressure wave. In their summary the NASA engineers concluded that this would be possible with fuel reforming systems controlled by a closed loop computerized control system. Unfortunately, they did not have these control systems readily available to them in 1977. But we have this type of technology in common use today. While, electrolysis based hydrogen injection may not be the answer to reach optimal fuel efficiencies, they are the easiest to produce and test. Significant fuel economy gains are being produced by individuals and companies around the world with well designed safe units. But, Steam reforming systems are where near optimal fuel efficiency gains are currently being realized.

Steam reforming systems utilize the waste heat from the exhaust system to produce hydrogen in higher concentrations than electrolysis and reform the gasoline (or any primary fuel) to smaller components that combust much faster. By using the hydrogen to reduce ignition lag to lowest possible time and reforming the fuel to be fully consumed in the shortest period possible, near optimal fuel efficiencies are being reached. At the same time greenhouse gas and hydrocarbon emissions are greatly reduced. While most of the steam reformer systems available are using gasoline, it has been shown that some alternative fuels work even better. Fuels that contain large amounts of water work the best, with the added advantage that they do not require any additional storage/delivery system for water. The water to produce hydrogen and steam for the reforming process is available directly from the fuel.

 

[russ_watters]

While that may be the case, the study clearly showed that energy input was not the mechanism that created the increase in efficiency.

I didn't say it did. In fact, I said nothing whatsoever about the mechanism. I only analyzed the resulting numbers. You missed my point completely.

The gain was made with less system loss on the back end. Less energy was lost out the exhaust, more energy from the combustion is captured by the piston and converted to torque. By reducing ignition lag and increasing flame speed the energy of combustion is concentrated closer to the beginning of the power stroke so the piston has more time and travel to convert more of this energy.

That's all quite true, but the numbers are still the numbers.

Since nearly 85% of the energy produced by combustion is lost as heat out the exhaust, there is plenty of room for efficiency improvement here.

No, there isn't. A quick look at the efficiency equations or calculator for ideal Otto cycle shows the maximum possible efficiency is around 55-60%. It isn't possible - even in theory - to exceed that. And that's before you take away even the mechanical losses.

Another way to look at it: billions and billions of dollars have been pumped into researching these engines over the past hundred years. It would be illogical to believe that there is a shortcut to a massive improvement in efficiency.

While, electrolysis based hydrogen injection may not be the answer to reach optimal fuel efficiencies, they are the easiest to produce and test. Significant fuel economy gains are being produced by individuals and companies around the world with well designed safe units. But, Steam reforming systems are where near optimal fuel efficiency gains are currently being realized.

Please keep the forum guidelines in mind when discussing this subject. I'm giving quite a bit of leeway here, but the reality is that there is no scientific controversy on this issue, but there is a ton of crackpottery. Claims such as those are not supported by the science of the issue. It is a crackpot claim and I will not allow discussion of a crackpot claim here.

 

[russ_watters]

That much? Surprising. I was under the impression that the burn was already highly efficient and most of the loss was in the nature of the mechanically driven heat engine regardless of burn efficiency.

Dunno, is 9% a lot? Keep in mind that when you add hydrogen, you are adding football rules to baseball. You can pour a billion dollars into a typical gas engine and only squeeze another percent or two efficiency out of it, but once you start playing with other fuels, you change the rules of the game somewhat. Since the 9% doesn't include the losses from generating the hydrogen or the cost of the generator, I don't consider 9% to be a lot.

So that rules out on board generation but what if you bottle H2 locally? For instance: Some renewable source of energy...

Once you bring up renewable energy, there isn't anything left to talk about: if the energy is free, the energy is free. You can use it however you want. If you have free hydrogen on hand, why bother with the gasoline at all?

 

[mheslep]

...Once you bring up renewable energy, there isn't anything left to talk about: if the energy is free, the energy is free. You can use it however you want. If you have free hydrogen on hand, why bother with the gasoline at all?

Well of course the energy is only 'free' in the sense that its never exhausted, it still has an economic cost and that can be compared to the $/bbl cost of fuel.

 

[RMForbes]

I didn't say it did. In fact, I said nothing whatsoever about the mechanism. I only analyzed the resulting numbers. You missed my point completely. That's all quite true, but the numbers are still the numbers. No, there isn't. A quick look at the efficiency equations or calculator for ideal Otto cycle shows the maximum possible efficiency is around 55-60%. It isn't possible - even in theory - to exceed that. And that's before you take away even the mechanical losses.

I guess I really don't understand. Are you saying that modern engines are already getting optimum fuel economy? It seems obvious to me that they aren't. Just the fact there is unburnt fuel left at the end that needs to be dealt with, is proof to me. Maybe I just don't get it.

Another way to look at it: billions and billions of dollars have been pumped into researching these engines over the past hundred years. It would be illogical to believe that there is a shortcut to a massive improvement in efficiency. Please keep the forum guidelines in mind when discussing this subject. I'm giving quite a bit of leeway here, but the reality is that there is no scientific controversy on this issue, but there is a ton of crackpottery. Claims such as those are not supported by the science of the issue. It is a crackpot claim and I will not allow discussion of a crackpot claim here.

Don't ask me to understand the motivations of the auto industry, it has never made sense to me. All I know is that these steam reforming systems have been in use for decades. The auto industry has purchased hundreds of patents for fuel reforming systems and sat on them. That is public record. Do you know why they have not developed any of these patents?

While I appreciate the leeway, I thought that this forum was about the hydrogen economy. I was not aware that because some people are exploiting the basic principles of hydrogen injection in ways that can only be considered scams, that all hydrogen based systems were automatically proven invalid. That sounds like throwing the baby out with the bath water, thinking to me. The facts are good people and good companies are already getting incredible results by developing these principles, saving millions of gallons of fossil fuels with real systems. They are nothing like the Water4Gas type junk. I hope you are referring to these MLM type websites, I really don't think you would call me a crackpot.

 

[russ_watters]

I guess I really don't understand. Are you saying that modern engines are already getting optimum fuel economy? It seems obvious to me that they aren't.

No, I'm not. Fuel economy and thermodynamic efficiency are two very different things. You can, for example, decrease the weight and drag coefficient of a car and see a huge gain in fuel economy. But the engine that drives that car will have roughly the same thermodynamic efficiency as any other. The thermodynamic efficiency is what is pretty close to optimal.

That's for an engine powered exclusively by the Otto cycle, which includes virtually all of the hydrogen injection info we see (the ones that use the alternator and electrolysis). Connect an aft-end boiler of some sort and you can improve overall thermodynamic efficiency by quite a bit by adding a completely separate, secondary thermodynamic cycle.

Just the fact there is unburnt fuel left at the end that needs to be dealt with, is proof to me. Maybe I just don't get it.

Now that's a third thing. Combustion efficiency is not the same as thermodynamic efficiency or fuel economy. Combustion efficiency of a modern car is on the order of 95% and can't get any higher. These devices do not affect the combustion efficiency, they effect the thermodynamic efficiency by changing where and how the energy is applied in the thermodynamic cycle, not by changing how much energy is expended in combustion. Combustion efficiency is a matter of chemistry: making sure you get all carbon dioxide and no carbon monoxide when you burn gas. And due to emissions regulations, the combustion process is very tightly computer controlled.

Do you know why they have not developed any of these patents?

They aren't technically/economically viable.

While I appreciate the leeway, I thought that this forum was about the hydrogen economy. I was not aware that because some people are exploiting the basic principles of hydrogen injection in ways that can only be considered scams, that all hydrogen based systems were automatically proven invalid. That sounds like throwing the baby out with the bath water, thinking to me. The facts are good people and good companies are already getting incredible results by developing these principles, saving millions of gallons of fossil fuels with real systems. They are nothing like the Water4Gas type junk. I hope you are referring to these MLM type websites, I really don't think you would call me a crackpot.

I was referring specifically to the electrolysis-based systems, which you cited in your claim. I don't know enough about the steam reforming ones to comment much, but it does have a similar smell to it.

 

[RMForbes]

Now that's a third thing. Combustion efficiency is not the same as thermodynamic efficiency or fuel economy. Combustion efficiency of a modern car is on the order of 95% and can't get any higher. These devices do not affect the combustion efficiency, they effect the thermodynamic efficiency by changing where and how the energy is applied in the thermodynamic cycle, not by changing how much energy is expended in combustion. Combustion efficiency is a matter of chemistry: making sure you get all carbon dioxide and no carbon monoxide when you burn gas. And due to emissions regulations, the combustion process is very tightly computer controlled.

I don’t want to belabor this point, but your suggestion that combustion efficiency is already near optimum is contrary to the conclusions of the NASA engineers. On the NASA channel early this week one of the NASA engineers was talking about engine efficiency in regards to an electric car they were testing. He stated that the electric car was about 85% efficient, all but 15% from the stored energy is converted to torque. He compared that to the gasoline engines, around 15% from the energy of combustion is converted to torque and 85% is lost as heat out the exhaust. He went on to say that diesel is only a couple points better than gasoline. In the 1977 study the NASA engineers found that adding hydrogen to gasoline reduced the energy lost as heat in the exhaust by as much as 37%. Some of that energy was lost to the cooling system but most was converted to torque. That sounds like a rather significant improvement in combustion efficiency to me, but I think we are just arguing symantics now.

Here is link to NASA study for those not familar with it.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770016170_1977016170.pdf

They aren't technically/economically viable. I was referring specifically to the electrolysis-based systems, which you cited in your claim. I don't know enough about the steam reforming ones to comment much, but it does have a similar smell to it.

Actually not true, most of the patents had working models that were well documented. Many of these basic ideas are being used in Europe but cannot be imported to the U.S. because of our protectionist laws. Do some research on SAAB engine enhancements, you may be surprised.

 

[vanesch]

Here is link to NASA study for those not familar with it.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770016170_1977016170.pdf

If you look at figure 11 on p 32, you see that the thermal efficiency of the motor goes from something like 29% for gasoline to 32% for gasoline/hydrogen.

That's the marginal gain Russ was talking about. And note that this was with a monster engine of 7.4 liters of 1969

 

[russ_watters]

If you look at figure 11 on p 32, you see that the thermal efficiency of the motor goes from something like 29% for gasoline to 32% for gasoline/hydrogen. That's the marginal gain Russ was talking about.

Right: about 9%. With bottled hydrogen (not generated by the engine).

And note that this was with a monster engine of 7.4 liters of 1969

I didn't think about that - that's before computer control of the combustion process. The combusion efficiency today is considerably better than it was back then. Just throw a gigantic engine at the car and don't worry about how efficient it is. Even besides that, iirc, emissions of everything but carbon dioxide have dropped 90% since the 1970s due to technology forced by regulation.

And again, that 9% is not combustion efficiency, it is thermodynamic efficiency. Though, a lot of the thermodynamic efficiency gain in the paper probably comes from gains in combustion efficiency due to the poor combustion efficiency at the time (as vanesch pointed out). RC, you really need to start paying attention to the difference.

 

[mheslep]

I don’t want to belabor this point, but your suggestion that combustion efficiency is already near optimum is contrary to the conclusions of the NASA engineers. On the NASA channel early this week one of the NASA engineers was talking about engine efficiency in regards to an electric car they were testing. He stated that the electric car was about 85% efficient, all but 15% from the stored energy is converted to torque. He compared that to the gasoline engines, around 15% from the energy of combustion is converted to torque and 85% is lost as heat out the exhaust. He went on to say that diesel is only a couple points better than gasoline. In the 1977 study the NASA engineers found that adding hydrogen to gasoline reduced the energy lost as heat in the exhaust by as much as 37%.

A heat engine such as the internal combustion engine can never be as efficient as the electric drive train. The heat engine efficiency is limited by thermodynamics.

 

[buffordboy23]

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

http://web.mit.edu/newsoffice/2003/plasmatron.html

 

[russ_watters]

I don’t want to belabor this point, but your suggestion that combustion efficiency is already near optimum is contrary to the conclusions of the NASA engineers.

As I have demonstrated, no it isn't. Heck, my company has a combustion gas analyzer. If you want, I'll stick it up the tailpipe of my car (already done that when I learned to use it) and take a picture of the output!

On the NASA channel early this week one of the NASA engineers was talking about engine efficiency in regards to an electric car they were testing. He stated that the electric car was about 85% efficient, all but 15% from the stored energy is converted to torque. He compared that to the gasoline engines, around 15% from the energy of combustion is converted to torque and 85% is lost as heat out the exhaust.

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. Electric motors are not. Electric motors can be up to about 96% efficient at converting electrical energy to mechanical energy. But thermodynamic engines that use the Otto cycle can only be about 50% efficient at converting heat energy to mechanical energy. They are a completely different animal. You really need to get onboard with this concept. If you don't understand why it is, you need to learn.

He went on to say that diesel is only a couple points better than gasoline.

Yes, the Otto and diesel cycles are similar. The biggest difference is the way the fuel burns and what it allows to be done: higher compression ratios in diesels.

In the 1977 study the NASA engineers found that adding hydrogen to gasoline reduced the energy lost as heat in the exhaust by as much as 37%. Some of that energy was lost to the cooling system but most was converted to torque. That sounds like a rather significant improvement in combustion efficiency to me, but I think we are just arguing symantics now.

Here is link to NASA study for those not familar with it.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770016170_1977016170.pdf

As vanesch noted, you aren't properly analyzing the results. The drop in exhaust temp was largely due to running the engine lean, but that isn't directly translateable to thermodynamic efficiency (someone mentioned it before: less fire + more air = cooler exhaust, but not necessarily improved efficiency). Not to worry, though: Thermodynamic efficiency was specifically listed in the results.

Actually not true, most of the patents had working models that were well documented. Many of these basic ideas are being used in Europe but cannot be imported to the U.S. because of our protectionist laws. Do some research on SAAB engine enhancements, you may be surprised.

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.