Na + H2O2 (50%) -> H2?

[Tony Bryer]

The web alone.
Not to mention memory under microcents per bit are two of the most
significant developments of all time.

Yes, but that was my point. These things (in one form or another) were
known when I was born. What has happened in my lifetime is them
becoming universal.

 

[David Harper]

My father was born just before the Wright brothers first flight and
lived through 15 years of Concorde (RIP) flight. In my 51 years I don't
see changes of this significance

(SNIP)

If you're 51 years old, then when you were born, the highest and
fastest a human had ever gone was about 15 miles up and about Mach 2.5
(about 800 meters/sec).

Now we have a spacecraft swinging around Saturn, probes outside the
solar system (over 12.5 *BILLION* miles away), people that have swung
around the moon and returned at over 11.1 km per second, spacecraft
that have exceed 68 km/s, and thousands of satellites in every orbital
plane you can imagine. And that's just advances in aerospace. You
don't think that's significant?

Also consider the advances made with the advent of computers,
medicine, etc.

Dave

 

[Thiophilus]

(SNIP)

If you're 51 years old, then when you were born, the highest and
fastest a human had ever gone was about 15 miles up and about Mach 2.5
(about 800 meters/sec).

Now we have a spacecraft swinging around Saturn, probes outside the
solar system (over 12.5 *BILLION* miles away), people that have swung
around the moon and returned at over 11.1 km per second, spacecraft
that have exceed 68 km/s, and thousands of satellites in every orbital
plane you can imagine. And that's just advances in aerospace. You
don't think that's significant?

Also consider the advances made with the advent of computers,
medicine, etc.

Fifty years ago daily life was much as it was today -- they had cars,
radio, TV, electric fridges, airplanes, comic books, and so on.

One hundred years ago it was much different. No radio or TV, no
airplanes (not even the Wright bros had an operable one then),
virtually no cars. No comic books. Maybe ice boxes instead of fridges.

That's not to say that there hasn't been tremendous advances in
science and engineering in the last 50 years. Obviously there has
been, and it's unprecedented. But daily life has not changed that much
in the last half-century compared to a whole century ago.

 

[David Harper]

...

Interesting dichotomy. Physics is understood, but the engineering is not
there yet. In this case, the physics is a couple of simple equations of
motion.

In terms of orbital mechanics? Yes. Although, I wouldn't call them
too simple. They're pretty complex differential equations.

In terms of heat transfer, fluid mechanics, etc? Not so much. Alot
of research to better understand these areas was conducted to actually
figure out what was going on before we attempted spaceflight, much
less a trip to the moon.

The engineering is a million little physics problems, some of which
are not solvable, but enough of which could be worked around to actually go
to the moon.

Interesting you say that. Alot of formulas used in fluid dynamics and
heat transfer are emperical, and not based on derivation alone. Two
days ago I had to review a CFD drag analysis by Boeing that took
something like 1000+ CPU hours (I believe they have several CPUs
working in parallel though), and alot of those emperical equations can
still be found in their software.

The idea that understanding the equations of flying to the
moon, if you can build the space craft, if you can reenter, is all the
understanding needed for the problem is simply mistaken. The whole real
physical problem of going was so complex that there was a lot of uncertainty
on those first launches.

Less uncertainty than there could have been, thanks to planes like the
X-15, X-2, etc...

Dave

 

[daestrom]

Much worse than what?

Sodium aluminum hydride:

NaAlH4 + 2 H2O --> NaAlO2 + 4 H2

Note that you produce 8 Kg of hydrogen for each 54 Kg of Alanate.

Okay, so check my math here....

For 90 kg of reactants (54kg of NaAlH4 and 36kg of H2O), you get 8kg of H2.
For each 1kg of H2 you can expect about 141.9 MJ of energy. That works out
to about 12.6 MJ per kg of reactants. If you don't carry the 2H2O, then it
would be 21 MJ per kg of NaAlH4.

And gasoline carries about 43.8 MJ/kg when reacted with air.

So, explain again how 12.6 MJ per kg is so competitive with 43.8 MJ/kg????

For the above example, 8 Kg of hydrogen are produced from each 23 Kg
of Lithium Borohydride.

Re-working for LiAlH4, I get 38kg for every 8kg of H produced, not 23kg
(7+27+4*1). But add on the 36kg of water and we have 74kg of reactants for
8kg of H. That works out to about 15.3 MJ per kg of reactants. Excluding
the water, we get about 29.87 MJ per kg of LiAlH4. Better, but not
tremendously so.

Don often points out how how energy dense gasoline is as if it is the
ultimate energy storage medium. It isn't. He may be a proponent of
gasoline but the SCIENCE is straightforward. Lithium Borohydride and
other hydrides contain more energy by mass AND VOLUME than gasoline.

Hmm, the above shows that LiAlH4 carries *less* energy per kg than gasoline.

And you seem to be forgetting about carrying the water needed. Gasoline at
least has the advantage that the other reactant can be taken directly from
the atmosphere. Getting these amounts of H2O directly from the atmosphere
is *not* as simple.

This is verifiable scientific fact.

Unless I made an error in my calculations, the 'scientific fact' would be
that hydrides still carry less energy per kg than gasoline.

Claiming that gasoline contains more energy than hydrides like lithium
aluminum hydride are contradictory to scientific fact.

Oh? Please show me the error in my calculations that shows 38kg LiAlH4
liberates 8kg of H for an energy of 8*141.9 = 1135.2 MJ from 38kg of 'fuel'.
And that is 1135.2/38 = 29.87MJ/kg. While gasoline contains ~43.8MJ/kg.
And that is *assuming* the water reactant doesn't have to be carried.

daestrom
P.S. Energy values for hydrogen and gasoline taken from...
http://www.uvi.edu/Physics/SCI3xxWeb/Energy/GasolineFAQ.html

 

[daestrom]

Well, if it were not for Microsoft and your use of outlook, the thread
may not have been mangled. I take the responsibility as I'm the one
who replied. I've often dropped a microsoft mangled thread because it is
not worth the effort. You may want to look into using netscape if only
for your newsreader.

But, to answer your question, no. AI, I believe, (as I don't have enough
knowledge under my belt), is unobtainable because the human physique
doesn't fit in the rules of a turing machine. There may be quantum
computing...

Best, Dan.

I think you'll find it isn't the news-reader that 'mangles' such threads.
It is the posting thru different news-servers. Such as I, that post via a
time-warner RR server. The messages don't get forwarded to all other
news-servers instantly. So someone reading/posting on another news-server
will see things out of order.

Blame it on the speed of conversation and that not all news-servers are
synchronized.

daestrom

 

[pragmatist]

My aim is to get H2 from H2O2 solution at room tempertaure using Na or
Ca at room temp, then heat H2O2 to O2 to do H2 combustion work.

If energy from H2O2 is the goal, why not just use the O2 from
catalytic decomposition of the peroxide, (there is also energy
produced), combined with an easier to obtain reducing agent than
alkalai metals?
There are no free lunches.
H2O2 is an oxygen source.
As reducing agents Na or Ca are more expensive than other fuels.
You have to use energy to split off the Hydrogen to act as a reducing
agent so why not simply supply a reducing agent in a more economical
way?

The energy cost of H2O2 is high as are the energy costs of Na or Ca.
What you propose makes little sense unless for a very special
application.
As others point out, the reactions are likely to be violent.
What are you up to?

As a side note, H2O2 was once used with alcohol as torpedo fuel, (WW
I IIRC), but this was a special case where oxygen had to be provided
to run a compact, isolated, high energy system with technology that
was primitive compared to what is now available.

Pragmatist -"Somedays it's just not worth chewing through the
Restraints."

 

[Dan Bloomquist]

...


understood.

^^^ note the dangling 'understood' generated by outlook....

Dan. Suppose that black powder were still the only fuel available. As you
know, you cannot get to the moon even on a mountain of black powder.

You have the physics to understand that.

You
would then have this wonderful physics to get to the moon, understand the
orbital mechanics in detail, but not be able to get there.

Yes, you have the physics to understand that.

The real physics
of going to the moon includes such disparate issues as making a reliable
engine. Finding a fuel that we can afford, that we can store (monatomic
hydrogen would make a great fuel), that will give us the performance we
need.

This describes technological advancement that would have to be evolved.
In 1965 we knew we would have pentium computers by now, but we couldn't
build them in 1965. The only physical surprise we have seen since 65 in
the field that I know of deals with magnetic domains. Lucky for us or we
would not have such powerfully dense and cheap hard drives.

Best, Dan.

 

[Dan Bloomquist]

I think you'll find it isn't the news-reader that 'mangles' such threads.
It is the posting thru different news-servers. Such as I, that post via a
time-warner RR server. The messages don't get forwarded to all other
news-servers instantly. So someone reading/posting on another news-server
will see things out of order.

Blame it on the speed of conversation and that not all news-servers are
synchronized.

Hi,
Please see the post where I point out the mangling of the position of
the word 'understood'. This is what I was speaking of.

daestrom

Best, Dan.

 

[Dan Bloomquist]

That was the main point of my entire response. One of the first
things I said was:



Was that unclear?

What kind of technological advance do you have in mind that doesn't
require the precursor of a new physics?

And the only "physical limitation" you cited was that it was not an
energy "source", but a "currency". I agreed with this in a later
post, when I understood exactly what you meant. Using it as a
currency eliminates the physical limitation you cited. This became a
non-issue.

Sources of energy are now a non issue? Sure, in that case, hydrogen
makes a wonderful fuel because now it is cheaper than fossils.

I'll repeat:
As hydrogen is not an energy source, the cost of the source is
compounded by the losses in the hydrogen vector. The limitation is
physical, and vision doesn't change that.

When I traced back, the drive behind most of my comments originated
from your following statement:


This statement assumes technological progress in other fields (i.e.
nanotech) won't become viable options first. That's when I questioned
your ability to foresee the future of technological innovation.

I'll repeat:
Probably science fiction for another 5 or 10 decades.

Perhaps our entire clash boils down to the fact that I'm more of an
optimist in terms of technological advances.

I'll repeat:
A new discovery in physics is rather unlikely and if/when it happens, it
won't just make hydrogen practical. As far as advancements go, they have
been very predictable. Look at Moore's Law for an example. Other than
the likes of high temperature superconductors, there have been no
surprises for going on a century.
---
Technological advancement is predictable based on known physics...

"The U.S. rocket program hit a wall in the late 1940's due to a lack
of understanding of supersonic physics."

http://zebu.uoregon.edu/~js/space/lectures/lec05.html

...(enter stage left) the X-15 program: to better understand
supersonic physics and figure out what was (and was not) possible.
But this is really a side point to our original discussion.

You can say the orbital mechanics was well understood. However, you
can't get to the moon with orbital mechanics alone. Other areas, such
as fluid mechanics, were also needed to get to the moon...and, as
mentioned before, the fluid dynamics of hypersonic flow was *NOT* well
understood. Two other major areas within the realm of physics that
had to be better understood to get to the moon include
super/hypersonic heat transfer (both in the engines and on re-entry
surfaces, also aided by the X-15 program) and solar physics/radiation
outside the Van Allen belts. There's plenty of others areas I'm sure
I'm forgetting or not aware of.

And all about evolving technology based on known physics. If they could
not have developed > mach 1 travel, it would have implied a new physics.

Dave

Best, Dan.

 

[Jed Checketts]

Okay, so check my math here....

For 90 kg of reactants (54kg of NaAlH4 and 36kg of H2O), you get 8kg of H2.
For each 1kg of H2 you can expect about 141.9 MJ of energy. That works out
to about 12.6 MJ per kg of reactants. If you don't carry the 2H2O, then it
would be 21 MJ per kg of NaAlH4.

And gasoline carries about 43.8 MJ/kg when reacted with air.

So, explain again how 12.6 MJ per kg is so competitive with 43.8 MJ/kg????

If we are talking about providing hydrogen to a fuel cell, the above
is already competitive from an overall energy density standpoint.
Remember, 43.8 MJ of energy in the form of gasoline will give you far
less energy than this in the form of hydrogen if a gasoline to
hydrogen reformer is used.

Hydrogen energy converted to electrical energy in a fuel cell is more
efficient than gasoline energy converted to mechanical energy via
pistons and a crankshaft. This efficiency greatly impacts the numbers
for overall energy density of the system including the fuel.
Likewise, if you are going to convert gasoline into hydrogen you need
a gasoline reformer which takes up space and is in many cases a large
component of the system. This must be factored into the energy
density numbers as it is part of an overall system.

Re-working for LiAlH4, I get 38kg for every 8kg of H produced, not 23kg
(7+27+4*1). But add on the 36kg of water and we have 74kg of reactants for
8kg of H. That works out to about 15.3 MJ per kg of reactants. Excluding
the water, we get about 29.87 MJ per kg of LiAlH4. Better, but not
tremendously so.

It should be (7+11+4) (I could be wrong about the 11 for Boron, it
could be 11.5 or something and I don't have this one memorized but 27
is for Aluminum). There is a big weight savings by substituting Boron
for Aluminum. However, when the entire system is considered, for a
variety of reasons including that the aluminate is easier to recycle
than the borate, my money is on Aluminum.

Hmm, the above shows that LiAlH4 carries *less* energy per kg than gasoline.

And you seem to be forgetting about carrying the water needed. Gasoline at
least has the advantage that the other reactant can be taken directly from
the atmosphere. Getting these amounts of H2O directly from the atmosphere
is *not* as simple.


Unless I made an error in my calculations, the 'scientific fact' would be
that hydrides still carry less energy per kg than gasoline.


Oh? Please show me the error in my calculations that shows 38kg LiAlH4
liberates 8kg of H for an energy of 8*141.9 = 1135.2 MJ from 38kg of 'fuel'.
And that is 1135.2/38 = 29.87MJ/kg. While gasoline contains ~43.8MJ/kg.
And that is *assuming* the water reactant doesn't have to be carried.

daestrom
P.S. Energy values for hydrogen and gasoline taken from...
http://www.uvi.edu/Physics/SCI3xxWeb/Energy/GasolineFAQ.html

For Lithium Borohydride it would be 1135/22 (I'm assuming you are
correct on the 1135 number) This is 51.6 MJ/kg which is higher than
the 43.8 MJ/kg you report for gasoline. And the energy density
number for the lithium hydride is MUCH higher than gasoline than even
the 51:44 ratio once you factor in the efficiency difference between a
fuel cell and a combustion engine.

About the water issue: Assuming that water doesn't have to be carried
is reasonable since MORE water is produced by the fuel cell than what
the hydrolysis would need:

4 H2 + 2 O2 --> 4 H2O *FUEL CELL*

LiAlH4 + 2 H2O --> LiAlO2 + 4 H2 *HYDROGEN TANK*

(Note that 2 times more water is produced by the fuel cell than what
is needed, meaning that water recovery from the fuel cell only has to
be a sloppy 50%. The rest could be converted to pure drinking water.
Not such a bad byproduct.

Jed Checketts
Searles Lake, CA

 

[David Harper]

What kind of technological advance do you have in mind that doesn't
require the precursor of a new physics?

I liken this question to asking someone in 1950 "How in the world
would a spacecraft re-enter the atmosphere without burning up?" Just
because you can't see an immediately practical solution doesn't mean
one doesn't exist or won't exist in the future.

However, as discussed before, maybe nanotech... maybe just cheaper
ways to bottle solar using hydrogen as a currency.

Sources of energy are now a non issue? Sure, in that case, hydrogen
makes a wonderful fuel because now it is cheaper than fossils.

I'll repeat:
As hydrogen is not an energy source, the cost of the source is
compounded by the losses in the hydrogen vector. The limitation is
physical, and vision doesn't change that.

Fossil fuels do not provide a source of unlimited, already flowing,
almost-free energy. That's why you're so concerned with the "losses
in the hydrogen vector".

If you get hydrogen from a solar source, the losses in the hydrogen
vector aren't really an issue because you're just tapping already
released energy. As mentioned before, this is not the case with
fossil. Sure, going 100 miles on a tank of hydrogen might require
more energy than using current fossil fuels... but if it's coming from
an already tapped, much-cheaper, unlimited source, then efficiency
(assuming it's not ridiculously low) becomes a footnote.

I'll repeat:
Probably science fiction for another 5 or 10 decades.

Yes, probably. And I'll repeat: probably, but *possible*. You said
that hydrogen "would have to come from a nuclear driven thermochemical
processes". Now you say "probably". I guess you're conceeding your
original statement *might not* ultimately be correct?

I'll repeat:
A new discovery in physics is rather unlikely and if/when it happens, it
won't just make hydrogen practical. As far as advancements go, they have
been very predictable. Look at Moore's Law for an example. Other than
the likes of high temperature superconductors, there have been no
surprises for going on a century.
---
Technological advancement is predictable based on known physics...



And all about evolving technology based on known physics.

So you're stating that super/hypersonic flight was a "known physics"
in 1950? Maybe you should re-read the above quote:

"The U.S. rocket program hit a wall in the late 1940's due to a lack
of understanding of supersonic physics."

The physics of going to the moon was not a "known physics".
Technological evolution alone could not have gotten us to the moon in
1950. We had to learn more first via experiments, tests, etc.

Dave

 

[Don Lancaster]

If you get hydrogen from a solar source, the losses in the hydrogen
vector aren't really an issue because you're just tapping already
released energy.

Dave

There are three elements to an energy delivery system: (1) The cost of
the feedstock, (2) the cost of the infrastructure, and (3) the
amortization of the system.

(2) and (3) almost always dominate.

Hydrogen-anything is virtually certain to be noncompetitive with other
options. Because of unmanagable (2) and (3).

Especially if there is an electrical intermediary stage thus creating a
staggering loss of exergy.

See http://www.tinaja.com/glib/energfun.pdf for a detailed analysis.


--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Dan Bloomquist]

I liken this question to asking someone in 1950 "How in the world
would a spacecraft re-enter the atmosphere without burning up?" Just
because you can't see an immediately practical solution doesn't mean
one doesn't exist or won't exist in the future.

You didn't answer the question.

Instead, you seem to have created a 1950 question as if it were some
fundamental truth.

However, as discussed before, maybe nanotech... maybe just cheaper
ways to bottle solar using hydrogen as a currency.

And predictably, at least 5 decades off. At that, you still won't beat
back the physical limitation. With thermochemical processes running 60%
efficient, I fail to see how nanotech will revolutionize the use of
hydrogen.

Fossil fuels do not provide a source of unlimited, already flowing,
almost-free energy. That's why you're so concerned with the "losses
in the hydrogen vector".

You are claiming my concern?

If you get hydrogen from a solar source, the losses in the hydrogen
vector aren't really an issue because you're just tapping already
released energy. As mentioned before, this is not the case with
fossil. Sure, going 100 miles on a tank of hydrogen might require
more energy than using current fossil fuels... but if it's coming from
an already tapped, much-cheaper, unlimited source, then efficiency
(assuming it's not ridiculously low) becomes a footnote.

This has been beat to death on these threads. If you don't displace
fossil sources of energy with that solar, and produce hydrogen instead,
it does nothing but make some folks feel fuzzy good. This hydrogen has
the equivalent effect of getting 5 or 10 percent, (depending on the
technology), of the heating value of coal to the wheels of a vehicle.

The only way what you write can look good is to deny the real world
accounting of energy.

Yes, probably. And I'll repeat: probably, but *possible*. You said
that hydrogen "would have to come from a nuclear driven thermochemical
processes". Now you say "probably". I guess you're conceeding your
original statement *might not* ultimately be correct?

Do you know why I use the word 'probably'?
--circle one: yes, no --

And I'll repeat it again:
"Hydrogen as a 'fuel' has serious physical limitation." Technological
innovation does not defeat physical limitations.

The limitations are:
It is not an energy source.
It has a very poor energy density.
It suffers losses during handling at somewhat reasonable energy densities.

So you're stating that super/hypersonic flight was a "known physics"
in 1950? Maybe you should re-read the above quote:

"The U.S. rocket program hit a wall in the late 1940's due to a lack
of understanding of supersonic physics."

You seem to be hanging your hopes for hydrogen on this journalist's
words. Here is the timeline supersonic science:

http://history.nasa.gov/SP-4219/Chapter3.html

Notice that the fine tuning of Mach's work was done in the 30s. Now date
Mach...

The physics of going to the moon was not a "known physics".
Technological evolution alone could not have gotten us to the moon in
1950. We had to learn more first via experiments, tests, etc.

If you are going to make this claim, please cite the unknown physics of
going to the moon in 1950.

Dave

Best, Dan.

 

[David Harper]

Fine, further discussion of hydrogen as a fuel won't get us anywhere.
However, I can't let the following comments slide.

You seem to be hanging your hopes for hydrogen on this journalist's
words.

If you'd read the article, you'd realize he wasn't a journalist, but a
*professor* in physics.

Here is the timeline supersonic science:

http://history.nasa.gov/SP-4219/Chapter3.html

Notice that the fine tuning of Mach's work was done in the 30s. Now date
Mach...

This is another outlandish statement. If Mach's work had been "fine
tuned" in the 30's, the following would not have happened (by the way,
this is from the source *YOU* cited):

"The general aeronautics community was suddenly awakened to the
realities of the unknown flight regime in November 1941, when Lockheed
test pilot Ralph Virden could not pull the new, high-performance P-38
out of a high-speed dive, and crashed."

After this incident:
"Indeed, it was time for real airplanes to be used to probe the
mysteries of the unknown transonic gap. It was time for the high-speed
research airplane to become a reality."

(again, from your own source)

Mach did some groundbreaking work, but showing shock waves on a bullet
isn't all the info NASA needed on HYPERsonic flow to go to the moon.

From *YOUR OWN* article:

"John Stack nicely summarized the situation in 1938:

The development of the knowledge of compressible-flow phenomena,
particularly as related to aeronautical applications, has been
attended by considerable difficulty. The complicated nature of the
phenomena has resulted in little theoretical progress, and, in
general, recourse to experiment has been necessary. Until recently the
most important experimental results have been obtained in connection
with the science of ballistics, but this information has been of
little value in aeronautical problems because the range of speeds for
which most ballistic experiments have been made extends from the speed
of sound upward; whereas the important region in aeronautics at the
present time extends from the speed of sound downward."

Also (from your own article):

"In order to learn about the aerodynamics of transonic flight, the
only recourse appeared to be a real airplane that would fly in that
regime."

If you are going to make this claim, please cite the unknown physics of
going to the moon in 1950.

See above. I think your article just did for me.

Dave

 

[Dan Bloomquist]

Fine, further discussion of hydrogen as a fuel won't get us anywhere.
However, I can't let the following comments slide.

Would you agree we should not put our hopes for energy solutions into
hydrogen?

If you'd read the article, you'd realize he wasn't a journalist, but a
*professor* in physics.

I did not see the name of an author at the beginning or end of the
article. So, I don't know why I should accept the quote blindly.

Here is the timeline supersonic science:



This is another outlandish statement. If Mach's work had been "fine
tuned" in the 30's, the following would not have happened (by the way,
this is from the source *YOU* cited):

"The general aeronautics community was suddenly awakened to the
realities of the unknown flight regime in November 1941, when Lockheed
test pilot Ralph Virden could not pull the new, high-performance P-38
out of a high-speed dive, and crashed."

After this incident:
"Indeed, it was time for real airplanes to be used to probe the
mysteries of the unknown transonic gap. It was time for the high-speed
research airplane to become a reality."

(again, from your own source)

Mach did some groundbreaking work, but showing shock waves on a bullet
isn't all the info NASA needed on HYPERsonic flow to go to the moon.

From *YOUR OWN* article:

"John Stack nicely summarized the situation in 1938:

The development of the knowledge of compressible-flow phenomena,
particularly as related to aeronautical applications, has been
attended by considerable difficulty. The complicated nature of the
phenomena has resulted in little theoretical progress, and, in
general, recourse to experiment has been necessary. Until recently the
most important experimental results have been obtained in connection
with the science of ballistics, but this information has been of
little value in aeronautical problems because the range of speeds for
which most ballistic experiments have been made extends from the speed
of sound upward; whereas the important region in aeronautics at the
present time extends from the speed of sound downward."

Also (from your own article):

"In order to learn about the aerodynamics of transonic flight, the
only recourse appeared to be a real airplane that would fly in that
regime."




See above. I think your article just did for me.

The Bell X-1 broke the 'sound barrier' in 1947 and it wasn't an
accident. It was not done with an unknown science.

So, back to the point. In 1950 it was understood that a rocket could get
a man to the moon. It was understood that there was no physical
limitation to stand in the way. They knew perfectly well it was only a
mater of developing the technology.

Hydrogen has physical limitations. It is not a matter of developing some
technology to make it a viable energy vector.

Dave

Best, Dan.

 

[daestrom]

If we are talking about providing hydrogen to a fuel cell, the above
is already competitive from an overall energy density standpoint.
Remember, 43.8 MJ of energy in the form of gasoline will give you far
less energy than this in the form of hydrogen if a gasoline to
hydrogen reformer is used.

Hydrogen energy converted to electrical energy in a fuel cell is more
efficient than gasoline energy converted to mechanical energy via
pistons and a crankshaft. This efficiency greatly impacts the numbers
for overall energy density of the system including the fuel.
Likewise, if you are going to convert gasoline into hydrogen you need
a gasoline reformer which takes up space and is in many cases a large
component of the system. This must be factored into the energy
density numbers as it is part of an overall system.




It should be (7+11+4) (I could be wrong about the 11 for Boron, it
could be 11.5 or something and I don't have this one memorized but 27
is for Aluminum). There is a big weight savings by substituting Boron
for Aluminum. However, when the entire system is considered, for a
variety of reasons including that the aluminate is easier to recycle
than the borate, my money is on Aluminum.

Yea, my bad. I saw the LiAlH4 formula, and the 23Kg and completely missed
where you switched to LiBH4.

For Lithium Borohydride it would be 1135/22 (I'm assuming you are
correct on the 1135 number) This is 51.6 MJ/kg which is higher than
the 43.8 MJ/kg you report for gasoline. And the energy density
number for the lithium hydride is MUCH higher than gasoline than even
the 51:44 ratio once you factor in the efficiency difference between a
fuel cell and a combustion engine.

About the water issue: Assuming that water doesn't have to be carried
is reasonable since MORE water is produced by the fuel cell than what
the hydrolysis would need:

4 H2 + 2 O2 --> 4 H2O *FUEL CELL*

Now it's getting interesting. By eliminating the need to carry 36kg of H2O
for every 22kg of 'fuel', it looks more promising.

What are you assuming for fuel-cell, controller, motor losses. An often
used number for gasoline to wheels is ~20%. Advanced electric motor can be
+90% and controllers of VFD often run in the 85% to 90% range. But which of
the *many* different numbers quoted efficiencies for fuel cells are you
assuming?

LiAlH4 + 2 H2O --> LiAlO2 + 4 H2 *HYDROGEN TANK*

What is the heat of formation/reduction of this reaction? Is it exothermic
or endothermic? If exo, is there any use for this energy on the vehicle or
is it a 'loss'? Since this fuel is manufactured, I presume that any energy
liberated in the above reaction must be supplied in the manufacture of the
fuel. And unless it can be recovered on the vehicle, it would be an
'infrastructure' loss. Not that gasoline doesn't have a lot of
'manufacture/infrastructure' losses, but it would be good to have some
comparitive information about this part of the fuel cycle.

daestrom

 

[Brett]

Would you agree we should not put our hopes for energy solutions into
hydrogen?


I did not see the name of an author at the beginning or end of the
article. So, I don't know why I should accept the quote blindly.


The Bell X-1 broke the 'sound barrier' in 1947 and it wasn't an
accident. It was not done with an unknown science.

So, back to the point. In 1950 it was understood that a rocket could get
a man to the moon. It was understood that there was no physical
limitation to stand in the way. They knew perfectly well it was only a
mater of developing the technology.

Hydrogen has physical limitations. It is not a matter of developing some
technology to make it a viable energy vector.


Best, Dan.

Fellas, please forgive me, even though I find this subject extremely
interesting, what does this have to do with electronics repair?

 

[David Harper]

Would you agree we should not put our hopes for energy solutions into
hydrogen?

Yes. If I had to bet, I wouldn't put hydrogen as a front-runner of
possible candidates to replace/supplement fossil (nor did I ever say I
think it was). However, I would not discount it either. It's
certainly possible. Only the future will tell.

I did not see the name of an author at the beginning or end of the
article. So, I don't know why I should accept the quote blindly.

But you assumed he was a journalist?

Go down a directory:
http://zebu.uoregon.edu/~js/

He's a professor.

The Bell X-1 broke the 'sound barrier' in 1947 and it wasn't an
accident. It was not done with an unknown science.

You're making one enormous assumption with this statement: that in
order for something to be accomplished, *everything* about it has to
be understood before hand. This is most certainly not true. If your
statement is correct, then explain the following:

1. Fact: the X-1's original contract called for it to be stable up to
only 0.8 Mach. Why didn't they design it for 1.0 Mach if they
understood supersonic flight? The fact is, they didn't know what kind
of effects they'd encounter over 0.8 Mach. That's why they did many,
many incremental flights slowly increasing in speed, and adjusting
things based on knowledge gained.

If they completely understood supersonic flight from the beginning,
why didn't they just break the sound barrier on the first flight?

2. The X-1 lost its elevator effectiveness when it first reached
about .94 Mach. This was not unexpected by the designers. If
supersonic flight was truely understood, then why was this allowed to
happen? (note the word "discovery" in the following quote):

"So important was this discovery that nearly every transonic and
supersonic aircraft since that time has had an all-movable horizontal
stabilizer..."

http://www.dfrc.nasa.gov/History/HistoricAircraft/X-1/techdata.html

3. The X-1 had straight wings. Look at every supersonic aircraft
after that. They have swept wings. Why? Because engineers didn't
fully understand the advantages of swept wings in terms of supersonic
flight. Or do you have another suggestion?

If you need some more quotes, here's a few:

[of the x-planes]
"Their sole purpose was to explore and document the unknown."

"The unusual part was that these aircraft had no obvious purpose other
than expanding our knowledge of aeronautics."

http://oea.larc.nasa.gov/PAIS/Supersonic.html

"Although the X-15 has provided much new knowledge about this
once-feared region, its return journey from there has proved even more
fruitful."

"...reentry flight has been mastered, and many previous unknowns no
longer remain."

http://www.hq.nasa.gov/office/pao/History/SP-60/ch-1.html

So, back to the point. In 1950 it was understood that a rocket could get
a man to the moon.

Actually, your original comment was:
"In 1950 the physics of going to the moon was well understood."

They knew it might be "possible". Saying we KNEW it could be done in
1950 is false. What if solar radiation outside the Van Allen belts
had been 100,000 times what it really is? What if the X-15 had
experienced aerodynamic heating that heated the leading edges to 2200F
at only Mach 3.5 instead of 6.7? Hindsight's 20/20, and these were
unknowns in 1950.

It was understood that there was no physical
limitation to stand in the way.

See above comments. You're saying people in 1950 could predict the
future with 100% accuracy. Also, your forgetting an additional point
of mine was that it only took 20 years from 1950. Sure, alot of
people probably figured it might be possible to get to the moon (once
the knowledge AND technology developed), but how many people would
have thought it possible in only 20 years?

Dave

 

[Dan Bloomquist]

Would you agree we should not put our hopes for energy solutions into
hydrogen?

Yes. If I had to bet, I wouldn't put hydrogen as a front-runner of
possible candidates to replace/supplement fossil (nor did I ever say I
think it was). However, I would not discount it either. It's
certainly possible. Only the future will tell.

I did not see the name of an author at the beginning or end of the
article. So, I don't know why I should accept the quote blindly.

But you assumed he was a journalist?

Go down a directory:
http://zebu.uoregon.edu/~js/

He's a professor.

The Bell X-1 broke the 'sound barrier' in 1947 and it wasn't an
accident. It was not done with an unknown science.

You're making one enormous assumption with this statement: that in
order for something to be accomplished, *everything* about it has to
be understood before hand. This is most certainly not true. If your
statement is correct, then explain the following:

1. Fact: the X-1's original contract called for it to be stable up to
only 0.8 Mach. Why didn't they design it for 1.0 Mach if they
understood supersonic flight? The fact is, they didn't know what kind
of effects they'd encounter over 0.8 Mach. That's why they did many,
many incremental flights slowly increasing in speed, and adjusting
things based on knowledge gained.

If they completely understood supersonic flight from the beginning,
why didn't they just break the sound barrier on the first flight?

2. The X-1 lost its elevator effectiveness when it first reached
about .94 Mach. This was not unexpected by the designers. If
supersonic flight was truely understood, then why was this allowed to
happen? (note the word "discovery" in the following quote):

"So important was this discovery that nearly every transonic and
supersonic aircraft since that time has had an all-movable horizontal
stabilizer..."

http://www.dfrc.nasa.gov/History/HistoricAircraft/X-1/techdata.html

3. The X-1 had straight wings. Look at every supersonic aircraft
after that. They have swept wings. Why? Because engineers didn't
fully understand the advantages of swept wings in terms of supersonic
flight. Or do you have another suggestion?

If you need some more quotes, here's a few:

[of the x-planes]
"Their sole purpose was to explore and document the unknown."

"The unusual part was that these aircraft had no obvious purpose other
than expanding our knowledge of aeronautics."

http://oea.larc.nasa.gov/PAIS/Supersonic.html

"Although the X-15 has provided much new knowledge about this
once-feared region, its return journey from there has proved even more
fruitful."

"...reentry flight has been mastered, and many previous unknowns no
longer remain."

http://www.hq.nasa.gov/office/pao/History/SP-60/ch-1.html

So, back to the point. In 1950 it was understood that a rocket could get
a man to the moon.

Actually, your original comment was:
"In 1950 the physics of going to the moon was well understood."

They knew it might be "possible". Saying we KNEW it could be done in
1950 is false. What if solar radiation outside the Van Allen belts
had been 100,000 times what it really is? What if the X-15 had
experienced aerodynamic heating that heated the leading edges to 2200F
at only Mach 3.5 instead of 6.7? Hindsight's 20/20, and these were
unknowns in 1950.

It was understood that there was no physical
limitation to stand in the way.

See above comments. You're saying people in 1950 could predict the
future with 100% accuracy. Also, your forgetting an additional point
of mine was that it only took 20 years from 1950. Sure, alot of
people probably figured it might be possible to get to the moon (once
the knowledge AND technology developed), but how many people would
have thought it possible in only 20 years?

Hi Dave,
I'll concede. In the light of the information you have provided, my
original comment should be considered wrong.

But at the least, they had a science to grind on. What I don't see is a
hydrogen science with mysteries to solve. And I've been all over the
hydrogen thing. So, at least without new information, I don't believe
hydrogen can be made part of an energy solution. There may be some kind
of material science breakthrough to conquer the storage problem, but
that just a rather small 'if' from here.

Dave

Thanks, Dan.