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Moosh! · Guest

A recent study warns of the danger of releasing hydrogen itself into
the atmosphere. Los Alamos researcher Thom Rahn led a team of
scientists from California universities and the National Center for
Atmospheric Research in Boulder, Colo. Their study of the natural
cycle of atmospheric hydrogen was recently published in the British
science journal Nature, and finds that substantially increased
hydrogen production has the potential to damage the upper atmosphere.

Escaped hydrogen could build up, depleting the ozone layer near the
North and South poles and triggering an increase in global warming.
The study also warns that hydrogen may further contribute to global
warming by aiding other chemicals in producing increased amounts of
water vapor in the upper atmosphere.

"It is impossible to manufacture, store and transport hydrogen without
at least some fractional loss (to the atmosphere)," Rahn said.

Researchers from the California Institute of Technology estimate that
leaked hydrogen in a hydrogen economy could cause as much as a 10
percent decrease in the stratospheric zone. If hydrogen replaces
fossil fuels as the world>s main energy source, the researchers
believe that each year 60 trillion to 120 trillion grams of hydrogen
could be released into the atmosphere. This is four to eight times the
amount that is currently released.

From:

http://www.pbs.org/newshour/science/hydrogen/environment.html

Cyril Meynier · Guest

Retrouvons en direct Moosh! <less@even.less>, notre envoyé(e)
spécial(e) sur sci.energy.hydrogen:

[quote]
Researchers from the California Institute of Technology estimate that
leaked hydrogen in a hydrogen economy could cause as much as a 10
percent decrease in the stratospheric zone.
[/quote]
These are present-day statistic.

However, if the "hydrogen economy" ever becomes a reality, H2 will be
handled much better than now. Technology will be improved while
hydrogen gets more and more used. Similarly, now that natural gas is
extensively used, it is handled much better, with much less leaks than
is the early years of its use.

If hydrogen economy does not become a reality, there is no such
problem either.

I have long been surprised by the tone of hydrogen debate. It is
almost a ideological fight.

Some people are absolutely sure that H2 will become the main energy
source. Well, of course, it is not a source, it is a vector, that is
manufactured somewhere using some primary source, to be used elsewhere
by a final custumer. So is electricity, after all.

These hydrogen-bug people seems to believe that hydrogen will be used
and produce everywhere, sometimes against obvious economical logic :
they believe that some electricity plants will run on hydrogen
produced by fuel gasification, while some factories will produce
hydrogen from electricity (electrolisys). Nonsense : electrolisys
would be used if H2 is more expensive than electricity, H2-fed power
plants would be used in the opposite case.

Other people totally refuse to believe that H2 could be used anywhere,
even for stationnary apoplications - while it is already extensivily
used in various industries.

In fact, nobody can say, and for now we must rely on R&D, that will
say wether, for instance, an hydrogen car is possible.

If not, methanol is an alternative. Like hydrogen, it can be produced
from various primary sources, and be used in fuel cells (but with
lower efficency).

--
"Die Naturwissenschaft ohne Religion ist lahm, die Religion ohne Naturwissenschaft ist blind. "
Einstein

Don Lancaster · Guest

Cyril Meynier wrote:
[quote]

If hydrogen economy does not become a reality, there is no such
problem either.

[/quote]
"hydrogen economy" is an oxymoron that ain>t gonna happen.
See http://www.tinaja.com/glib/energfun.pdf

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com fax 847-574-1462

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

Dan Bloomquist · Guest

Cyril Meynier wrote:
[quote]
I have long been surprised by the tone of hydrogen debate. It is
almost a ideological fight.

Not for me. It is a simple crunching of the numbers. Unless the _source_[/quote]
of energy is green, hydrogen will create far more CO2 than the direct
use of hydrocarbons or coal.

[quote]Some people are absolutely sure that H2 will become the main energy
source. Well, of course, it is not a source, it is a vector, that is
manufactured somewhere using some primary source, to be used elsewhere
by a final custumer. So is electricity, after all.

Electricity from coal nets 35% of the heat value. The electrolysis route[/quote]
is popular here. Then you would be lucky to see 7% of the heat value of
that coal make it to the wheels of an auto.

In the case of methane, (which we already import), it can be used
directly as a fuel. Why suffer the losses by using the hydrogen vector?

[quote]These hydrogen-bug people seems to believe that hydrogen will be used
and produce everywhere, sometimes against obvious economical logic :
they believe that some electricity plants will run on hydrogen
produced by fuel gasification, while some factories will produce
hydrogen from electricity (electrolisys). Nonsense : electrolisys
would be used if H2 is more expensive than electricity, H2-fed power
plants would be used in the opposite case.

The numbers are what count. (Pun?) It doesn>t matter if someone thinks[/quote]
hydrogen is a good thing or not. If the numbers say you are better
served by using other methods, well...

[quote]
Other people totally refuse to believe that H2 could be used anywhere,
even for stationnary apoplications - while it is already extensivily
used in various industries.

It shouldn>t be about beliefs. Until and unless energy sources are green[/quote]
and abundant, there are better ways. If we want to use electricity for
autos, an EV commuter will be 2 to 3 times more efficient than a
hydrogen fueled vehicle. As well as cheaper.

[quote]
In fact, nobody can say, and for now we must rely on R&D, that will
say wether, for instance, an hydrogen car is possible.

R&D is not going to make the hydrogen vector much more efficient. And it[/quote]
would take some major breakthroughs to bring the cost down.

If this is about being kinder to the environment or conserving fossils,
folks should start at home. Stop commuting, one person at a time, in
bumper to bumper traffic, in three ton vehicles.

[quote]If not, methanol is an alternative. Like hydrogen, it can be produced
from various primary sources, and be used in fuel cells (but with
lower efficency).

Alternatives make no sense until the source of energy is something other[/quote]
than fossils.

[quote]
--
"Die Naturwissenschaft ohne Religion ist lahm, die Religion ohne Naturwissenschaft ist blind. "
Einstein
[/quote]
Best, Dan.

--
http://lakeweb.net
http://ReserveAnalyst.com
dbAtLakewebDotCom

Cyril Meynier · Guest

Retrouvons en direct Dan Bloomquist <lakeweb@citlink.net>, notre
envoyé(e) spécial(e) sur sci.energy.hydrogen:

[quote]I have long been surprised by the tone of hydrogen debate. It is
almost a ideological fight.

Not for me. It is a simple crunching of the numbers. Unless the _source_
of energy is green, hydrogen will create far more CO2 than the direct
use of hydrocarbons or coal
[/quote]
Nobody denied that.

Their may be a escape way : carbon sequestration in geological
reservoirs. Bush seems to believe in this way (he just launched the
futuregen program).

But Sequestration will likely be very costly. I doubt there is really
an large-scale industrial future for such technology.

And it seems to be some kind of policital justification. It is only a
small (275 Mw), long term (2015) project. For now, the reality is that
he allowed several old, polluting coal-fired plants to be reactivated.

[quote]Electricity from coal nets 35% of the heat value. The electrolysis route
is popular here. Then you would be lucky to see 7% of the heat value of
that coal make it to the wheels of an auto.

In the case of methane, (which we already import), it can be used
directly as a fuel. Why suffer the losses by using the hydrogen vector?
[/quote]
Both coal and methane can be turned directly to hydrogen.

from coal :
C + 2H2O ->2H2 + CO2
in fact :
C + H2O -> C0 + H2 (syngas)
A reaction that has been used for decades. It was used around
1900 to produce city gas from coal. Some French build "gazogenes",
devices that used this reaction to run a car using coal or wood during
WWII. Several modern coal-fired plants (IGCC) uses thius reaction and
burn syngas in turbines.
Then :
CO + H2O -> CO2 + H2

for natural gaz
CH4 + H H2O -> 4H2 + CO2
also i two steps. This is known as reforming.

Both reactions are endothermic, efficinecy is somewhere in the 70-80 %
range. Much more that using electricity as an intermediate step.

Methane could be reformed using another heat source (solar, nuclear).

But CO2 emissions remains an issue. With a 50% efficient fuel cell, an
hydrogen car using H2 produced from natural gas would emit
(indirectly) somewhat less co2 than a gasoline car, but this is not a
huge differency.

IMHO, the big issue is whether the iodine-sulfur cycle, a catalytic
process expected to allow hydrogen production from heat (nuclear or
solar), with some 50% efficiency, will be a technical success.

[quote]If this is about being kinder to the environment or conserving fossils,
folks should start at home. Stop commuting, one person at a time, in
bumper to bumper traffic, in three ton vehicles.
[/quote]
Of course.

best
--
"Die Naturwissenschaft ohne Religion ist lahm, die Religion ohne Naturwissenschaft ist blind. "
Einstein

Dan Bloomquist · Guest

Cyril Meynier wrote:

[quote]In the case of methane, (which we already import), it can be used
directly as a fuel. Why suffer the losses by using the hydrogen vector?

Both coal and methane can be turned directly to hydrogen.

from coal :
C + 2H2O ->2H2 + CO2
in fact :
C + H2O -> C0 + H2 (syngas)
A reaction that has been used for decades. It was used around
1900 to produce city gas from coal. Some French build "gazogenes",
devices that used this reaction to run a car using coal or wood during
WWII. Several modern coal-fired plants (IGCC) uses thius reaction and
burn syngas in turbines.
Then :
CO + H2O -> CO2 + H2

for natural gaz
CH4 + H H2O -> 4H2 + CO2
also i two steps. This is known as reforming.

Both reactions are endothermic, efficinecy is somewhere in the 70-80 %
range. Much more that using electricity as an intermediate step.

[/quote]
This is true for C + 2H2O ->2H2 + CO2? I don>t have the numbers.
And while were at it, we could synthesize hydrocarbons from coal. Much
easier to handle than hydrogen.

[quote]Methane could be reformed using another heat source (solar, nuclear).

But CO2 emissions remains an issue. With a 50% efficient fuel cell, an
hydrogen car using H2 produced from natural gas would emit
(indirectly) somewhat less co2 than a gasoline car, but this is not a
huge differency.

[/quote]
50% is rather optimistic I think. Low temp fuel cells net more like 40%.
And the losses for handling hydrogen, whether compressed or cryogenic.

On the other hand, SOFCs and methane will get you 55% or more directly,
without bottom cycling. (80% with.) You don>t get power on demand from
SOFCs but not a big deal in a hybrid. And a power density of 2kwh/liter
at a much lower cost.

[quote]IMHO, the big issue is whether the iodine-sulfur cycle, a catalytic
process expected to allow hydrogen production from heat (nuclear or
solar), with some 50% efficiency, will be a technical success.

If this is about being kinder to the environment or conserving fossils,
folks should start at home. Stop commuting, one person at a time, in
bumper to bumper traffic, in three ton vehicles.

Of course.

As so many of our fleet miles are done in commutes, EVs would make the[/quote]
most sense. At least two times the efficiency of hydrogen and cheaper too.

[quote]
best
--
"Die Naturwissenschaft ohne Religion ist lahm, die Religion ohne Naturwissenschaft ist blind. "
Einstein
[/quote]
Best, Dan.

--
http://lakeweb.net
http://ReserveAnalyst.com
dbAtLakewebDotCom

Roland Paterson-Jones · Guest

"Dan Bloomquist" <lakeweb@citlink.net> wrote in message
news:3F9D7B3B.3090807@citlink.net...
[quote]Cyril Meynier wrote:

I have long been surprised by the tone of hydrogen debate. It is
almost a ideological fight.

Some people are absolutely sure that H2 will become the main energy
source. Well, of course, it is not a source, it is a vector, that is
manufactured somewhere using some primary source, to be used elsewhere
by a final custumer. So is electricity, after all.

Electricity from coal nets 35% of the heat value. The electrolysis route
is popular here. Then you would be lucky to see 7% of the heat value of
that coal make it to the wheels of an auto.
[/quote]
Dan, just to be a pain, that>s only a factor of 2 poorer than the conversion
of gasoline to auto wheels.

Roland

--
Roland and Lisa Paterson-Jones
Forest Lodge, Stirrup Lane, Hout Bay
http://www.rolandpj.com/forest-lodge
mobile: +27 72 386 8045
e-mail: forest-lodge@rolandpj.com

Roland Paterson-Jones · Guest

"Cyril Meynier" <meynier.cyril@//non_aus_pam//wanadoo.fr> wrote in message
news:i8vqpv06kgt3s33j3ipa169kbpgoftft6j@4ax.com...
[quote]Retrouvons en direct Dan Bloomquist <lakeweb@citlink.net>, notre
envoyé(e) spécial(e) sur sci.energy.hydrogen:

I have long been surprised by the tone of hydrogen debate. It is
almost a ideological fight.

Not for me. It is a simple crunching of the numbers. Unless the _source_
of energy is green, hydrogen will create far more CO2 than the direct
use of hydrocarbons or coal

Nobody denied that.

Their may be a escape way : carbon sequestration in geological
reservoirs. Bush seems to believe in this way (he just launched the
futuregen program).
[/quote]
Sequestration runs deeper than that, as covered by the Kyoto protocol (with
many caveats).

Aforestation (or reforestation), for example, can be achieved at a
geographically and economically removed location.

More trees = more sequestration of CO2, which will balance additional
coal-fired plants, for example.

Roland

--
Roland and Lisa Paterson-Jones
Forest Lodge, Stirrup Lane, Hout Bay
http://www.rolandpj.com/forest-lodge
mobile: +27 72 386 8045
e-mail: forest-lodge@rolandpj.com

Roland Paterson-Jones · Guest

Moosh, if you>d researched your sources, you would have found:

http://www.nature.com/nature/links/030821/030821-4.html

"High-precision measurements of the deuterium content of H2 in the
stratosphere now reveal that it becomes remarkably deuterium-rich owing to
the production of molecular hydrogen from methane oxidation"

The problem is not H2 but methane, which is an evil green-house gas already.

Roland

p.s. Nice wind-up dude!

--
Roland and Lisa Paterson-Jones
Forest Lodge, Stirrup Lane, Hout Bay
http://www.rolandpj.com/forest-lodge
mobile: +27 72 386 8045
e-mail: forest-lodge@rolandpj.com

"Moosh!" <less@even.less> wrote in message
news:5lv9pv8kofl9kunsk21kcdbli1j7a15coe@4ax.com...
[quote]A recent study warns of the danger of releasing hydrogen itself into
the atmosphere. Los Alamos researcher Thom Rahn led a team of
scientists from California universities and the National Center for
Atmospheric Research in Boulder, Colo. Their study of the natural
cycle of atmospheric hydrogen was recently published in the British
science journal Nature, and finds that substantially increased
hydrogen production has the potential to damage the upper atmosphere.

Escaped hydrogen could build up, depleting the ozone layer near the
North and South poles and triggering an increase in global warming.
The study also warns that hydrogen may further contribute to global
warming by aiding other chemicals in producing increased amounts of
water vapor in the upper atmosphere.

"It is impossible to manufacture, store and transport hydrogen without
at least some fractional loss (to the atmosphere)," Rahn said.

Researchers from the California Institute of Technology estimate that
leaked hydrogen in a hydrogen economy could cause as much as a 10
percent decrease in the stratospheric zone. If hydrogen replaces
fossil fuels as the world>s main energy source, the researchers
believe that each year 60 trillion to 120 trillion grams of hydrogen
could be released into the atmosphere. This is four to eight times the
amount that is currently released.

From:

http://www.pbs.org/newshour/science/hydrogen/environment.html[/quote]

Dan Bloomquist · Guest

Roland Paterson-Jones wrote:
[quote]"Dan Bloomquist" <lakeweb@citlink.net> wrote in message
news:3F9D7B3B.3090807@citlink.net...

Cyril Meynier wrote:

I have long been surprised by the tone of hydrogen debate. It is
almost a ideological fight.

Some people are absolutely sure that H2 will become the main energy
source. Well, of course, it is not a source, it is a vector, that is
manufactured somewhere using some primary source, to be used elsewhere
by a final custumer. So is electricity, after all.

Electricity from coal nets 35% of the heat value. The electrolysis route
is popular here. Then you would be lucky to see 7% of the heat value of
that coal make it to the wheels of an auto.

Dan, just to be a pain, that>s only a factor of 2 poorer than the conversion
of gasoline to auto wheels.

[/quote]
Hi Roland,

I have been using the 20% which looks to be the popular number for our
current fleet heat to wheels. And figuring 5% - 7%
coal-electricity-hydrogen-wheels, that>s 3 to 4 times worse.

I>m waiting to hear what the C + 2H20 -> CO2 + 2H2 efficiency is. If
70%+, that changes things.

[quote]Roland

[/quote]
Best, Dan.

--
http://lakeweb.net
http://ReserveAnalyst.com
dbAtLakewebDotCom

Cyril Meynier · Guest

Retrouvons en direct Dan Bloomquist <lakeweb@citlink.net>, notre
envoyé(e) spécial(e) sur sci.energy.hydrogen:

[quote]I>m waiting to hear what the C + 2H20 -> CO2 + 2H2 efficiency is. If
70%+, that changes things.
[/quote]
According to Departement Of Energy (in Futuregen-related papers), it
is 75% efficient.

Apply a 0.9 propaganda factor, you get 67.5%. :-)

--
"Die Naturwissenschaft ohne Religion ist lahm, die Religion ohne Naturwissenschaft ist blind. "
Einstein

Harry Conover · Guest

Dan Bloomquist <lakeweb@citlink.net> wrote in message news:<3F9F0860.3040407@citlink.net>...

[quote]I>m waiting to hear what the C + 2H20 -> CO2 + 2H2 efficiency is. If
70%+, that changes things.
[/quote]
Hmmm... I though that this reaction was: C + H2O -> CO + H2, the old
gashouse "Water Gas" process used to produce manufactured illuminating
gas.

How do you modify/re-configure this classic reaction to produce CO2 +
H2 without a loss of energy?

The more perplexing question is that of how to compute efficiency. My
best guess is that one would take the energy yield produced the the
combustion of the CO and the H2, then divide it by the energy
equivalent of the heat of combusion of carbon, in which case I would
predict a thermodynamic efficiency of less than 25% with respect to
the product yield. (Worse still, if the CO is oxidized to CO2 in a
subsequent conversion step.)

Then too, perhaps I>m missing something important which, not being a
chemical engineer, is entirely possible.

Harry C.

Harry Conover · Guest

Cyril Meynier <meynier.cyril@//non_aus_pam//wanadoo.fr> wrote in message news:<i8vqpv06kgt3s33j3ipa169kbpgoftft6j@4ax.com>...

[quote]
Both coal and methane can be turned directly to hydrogen.

from coal :
C + 2H2O ->2H2 + CO2
in fact :
C + H2O -> C0 + H2 (syngas)
A reaction that has been used for decades. It was used around
1900 to produce city gas from coal. Some French build "gazogenes",
devices that used this reaction to run a car using coal or wood during
WWII. Several modern coal-fired plants (IGCC) uses thius reaction and
burn syngas in turbines.
Then :
CO + H2O -> CO2 + H2

for natural gaz
CH4 + H H2O -> 4H2 + CO2
also i two steps. This is known as reforming.

Both reactions are endothermic, efficinecy is somewhere in the 70-80 %
range. Much more that using electricity as an intermediate step.
[/quote]
Sorry Cyril, I missed reading your post and to an extent duplicated
what you had written. No offense intended.

Still, I must take exception to your efficiency figures, since their
implication is a degree of reaction heat capture that is far greater
than that achievable in coventional coal burning energy production
facilities (which are highly optimized).

My guess is that the best efficiency achievable in the Water Gas
formation process is something like 20%, which the reformation process
is likely to knock down to 10% or so. Secondary loss in thermodynamic
efficiency is due to the fact that the reformation process itself is
unlikely to achive much more than 50% thermal efficiency, hence will
reduce the Water Gas energy yield by a roughly a factor of 2:1.

Harry C.

Dan Bloomquist · Guest

Harry Conover wrote:
[quote]Dan Bloomquist <lakeweb@citlink.net> wrote in message news:<3F9F0860.3040407@citlink.net>...

I>m waiting to hear what the C + 2H20 -> CO2 + 2H2 efficiency is. If
70%+, that changes things.

Hmmm... I though that this reaction was: C + H2O -> CO + H2, the old
gashouse "Water Gas" process used to produce manufactured illuminating
gas.

How do you modify/re-configure this classic reaction to produce CO2 +
H2 without a loss of energy?

The more perplexing question is that of how to compute efficiency. My
best guess is that one would take the energy yield produced the the
combustion of the CO and the H2, then divide it by the energy
equivalent of the heat of combusion of carbon, in which case I would
predict a thermodynamic efficiency of less than 25% with respect to
the product yield. (Worse still, if the CO is oxidized to CO2 in a
subsequent conversion step.)

Then too, perhaps I>m missing something important which, not being a
chemical engineer, is entirely possible.

Harry C.
[/quote]
Thanks Harry,
I>m not the chemist. I would hope Graham chimes in, he does this best.

Dan.

--
http://lakeweb.net
http://ReserveAnalyst.com
dbAtLakewebDotCom

Cyril Meynier · Guest

Retrouvons en direct hhc314@yahoo.com (Harry Conover), notre envoyé(e)
spécial(e) sur sci.energy.hydrogen:

[quote]Secondary loss in thermodynamic
efficiency is due to the fact that the reformation process itself is
unlikely to achive much more than 50% thermal efficiency, hence will
reduce the Water Gas energy yield by a roughly a factor of 2:1.
[/quote]
Efficiency seems to be linked to primary fuel used on one hand (as in
other technologiues, it is harder to use efficiently biomass or
lignite than high-grade coal, because of higher mineral content), and
the size of the chemical reactor on the other hand : a smaller reactor
have more radient thermal losses.

A small biomass-to-hydrogen plant is been built in Germany, with a
thermal power of 2.5 MWth, using low-quality biomass. Efficency is
only in the 50-60% range:
http://www.hyweb.de/News/arcv298e.html#Biomass%20gasification%20project%20april%2098-e

Steam pressure seems to be a important parameter too, since some
laboraties are working on gasification of biomass with supercritical
water.

It is not said wether CO + H2O -> CO2 + H2 is used or CO is burnt
directly.

Departement Of Energy *pomises* a75% for coal-to-hydrogen conversion
in Vision21 plants (for advanced large-scale gasificators), so i am
likely to expect a real figure in the 65-70% range.

Efficiency in undoubtly somewhat higher using methane as fuel, at some
70+% right now (not in 2020).

In all cases, this is much more than with electrolysys (whatever is
the efficiency of the electrolyser) : a state-of-the-art supercritical
coal-fired plant can give a 45% efficiency at best.

Capital cost is likely inferior too. A multi-MW electrolyser would be
very expensive.

From an ecological point of view, producing hydrogen from solar heat
would be much better. A canadian company is building a prototype :
http://www.sheclabs.com/

However, their site offer few accurate figures, no effiency figure is
given.

--
"Die Naturwissenschaft ohne Religion ist lahm, die Religion ohne Naturwissenschaft ist blind. "
Einstein


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