Re: H2 burner

On Jun 6, 10:20 pm, Eeyore <rabbitsfriendsandrelati...@xxxxxxxxxxx>
wrote:
Williamknowsbest wrote:
Harry

While we agree on the importance of marginal value we disagree on the
marginal value of hydrogen and its aafety.  Hydrogen is perfectly safe
as a fuel if handled properly.   Hydrogen using a sufficiently low
cost solar power system may be made available at costs competitive
with existing fuels.

A ton of hydrogen has the same heat value of 6.2 tons of coal.

And the volume of these at STP is ?

Graham

That is a singularly dumbass question. To see why this is so, lets
go over some of the basics of volumetric and gravimetric energy
density.

Volumetric energy density is how much energy you get per unit
volume.
Gravimetric energy density is how much energy you get per unit weight.

Standard Temperature and Pressure doesn't impact the volume of coal.
The specific gravity of bituminous coal is 1.32 - so, 1 cubic meter
contains 1.32 metric tons. Ground into a powder, its lower. So,
the volumetric energy density of coal is typically less than 30
gigajoules per cubic meter. Lignite which can be 60% water and 30%
carbon can have volumetric densities of 12 gigajoules per cubic meter.

STP doesn't impact oil either. Crude oil has a specific gravity of
0.76 to 0.83 depending on where its drawn from. Crude oil contains
41.7 Gigajoules per metric ton, so a cubic meter of oil is typically
less than 32 gigajoules per cubic meter.

STP doesn't impact methanol. Methanol has a specific gavity of 0.79
and a gravimetric energy density of 19.7 gigajoules per metric ton, so
it has a volumetric energy density of 15.6 gigajoules per cubic
meter. At STP methanol is a liquid. Howaver at 64.7C methanol boils,
and becomes a vapor. At that temperature it around 2 kg per cubic
meter - 500 cubic meters are needed to contain a ton at that
temperature and atmospheric pressure - so, a cubic meter of methanol
vapor contains 0.394 gigajoules of energy.

So, we can see gases are a different story. So, lets look at that
since hydrogen is a gas at STP.

STP is a valuable reference point,when tallking about gases, but tells
us nothing about how to use a gas efficiently.

Natural gas and hydrogen gas are interesting to compare for this
reason.

Natural gas has an energy density 53.6 gigajoules per metric ton, and
at STP contains 0.05 gigajoules per cubic meter - more than methanol
vapor at its boiling point - since 1072 cubic meters are needed to
contain a ton at STP. Even though the density of natural gas at STP
is less than methanol vapor at methanol's boiling point and both at
the same pressure -natural gas contains more energy per unit volume
than methanol.

Of course, natural gas is more typically used at 200x atmospheric
pressure 10 gigajoules per cubic meter iare achieved - which is
sufficient to provide efficient distribution and storage of the gas
and approaches 1/3 the volumetric energy density of crude oil and 2/3
the volumetric energy density of methanol in liquid state..

Hydrogen is even less dense than natural gas - but is more
compressible. Hydrogen gas has an energy density of 143 gigajoules
per metric ton. At STP a metric ton of hydrogen occupies a whopping
8,576 cubic meters - so hydrogen's energy denisty at STP is only 0.017
gigajoules per cubic meter of the gas.

Obviously, as with natural gas, hydrogen is stored and transmitted
only in a highly compressed state.

At the pressures established by the American Society of Mechanical
Engineers for hydrogen, 4.3 gigajoules per cubic meter are achieved.
Hydrogen's lower viscosity, means that the same sort of pipeline and
storage infrastructure efficiently transmits the gas to stationary
users on a national scale.

http://www.mac.doc.gov/china/Breakout%20D%20-%20Frikkin.pdf

In liquid form hydrogen achieves energy densities of 10 gigajoules per
cubic meter equal to that of natural gas and 2/3 that of methanol.
Which makes this liquid ideally suited for mobile applications where
clean exhaust is desired.

Gelled and slush mixtures of solid/liquid hydrogen can provide further
density increases.to 12.5 gigajoules per cubic meter - nearly half
that of crude oil and nearly that of methanol.

http://www-formal.stanford.edu/jmc/progress/hydrogen.html
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V1T-3YDG9GM-K&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=286b3f03487980b07fadd6d2ee4ec623

Which is why major manufacturers are building experimental vehicles
that burn liquid and gaseous hydrogen

http://www.bmw.com/com/en/insights/technology/efficient_dynamics/phase_2/clean_energy/bmw_hydrogen_7.html
http://www.flug-revue.rotor.com/FRheft/FRH9809/FR9809k.htm
http://www.sfu.ca/casr/ft-hdwpr.htm

The efficient storage, transmission and use of hydrogen in both
stationary and mobile applications has been solved. Clearly anyone
claiming otherwise is a throwback to an earlier time who is painfully
ignorant of recent advances and current technical art on the
subject.

The only issue facing humanity today is the efficient production of
hydrogen gas. This involves two paths;

(1) the use of regenerative systems and low cost sources of
renewable or nuclear electric power
(2) the low cost production of hydrogen from water using renewable
or nuclear power
(a) thermochemical
(b) electrochemical
(c) combinations

http://www1.eere.energy.gov/hydrogenandfuelcells/production/water_splitting.html


Table of volumetric energy densities of typical fuels

Jet A Fuel 33.0 GJ/m3
Crude Oil 31.7 GJ/m3
Bit. Coal 30.0 GJ/m3
Methanol 15.6 GJ/m3
Gel H2 12.5 GJ/m3
Lignite 12.0 GJ/m3
Liq. H2 10.0 GJ/m3
Nat Gas 10.0 GJ/m3 -at typical pressure
H2 Gas 4.3 GJ/m3 -at typical pressure
Meth Vap 0.39 GJ/m3 - at methanol boiling point
Nat Gas 0.05 GJ/m3 - at STP
H2 Gas 0.017 GJ/m3 - at STP

Obviously, hydrogen at STP is the lowest volumetric energy density on
the list. Clearly anyone who argues from this fact that hydrogen is
useless as an energy carrier is a fool. Hydrogen as a gel, as a
liquid, and as a compressed gas, fares well against other energetic
gases and liquids, and given the fact that its storage, transportation
and use has been all but resolved, any talk suggesting this is not so
is obviously ludicrous.

My solar panels produce hydrogen for $110 per metric ton - and using
ASME standard infrastructure that hydrogen is delivered anywhere in a
continental area on demand, for less than $200 per metric ton - making
it competitive with all other primary sources of energy.

.

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