Driving to a Hydrogen Future

Hydrogen and Fuel Cell Day took place earlier this month (10/08), atomic weight H is 1.008.

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bloggs.fredbloggs.fred
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weight H is 1.008.

One of the charms of hydrogen is that it can be fitted into the existing en ergy distribution network, and shipped through natural gas pipe lines.

The down-side is that about 25% of the energy that you use to electrolyse w ater gets turned energy that can drive your car.

Battery-powered cars exploit about 85% of the energy used to charge the bat tery.

We'd need about 30% more generating capacity than we've got if we went over to battery driven electric cars, about twice as much generating capacity a s we've got if we went over to electrolysis-fed hydrogen-powered cars.

And the nice thing about hydrogen from the perspective of the tax collectin g authority, is that hydrogen is going to be sold at refueling stations and can be taxed a whole lot more heavily than the regular electricity that is supplied by the grid, and looks exactly the same to the supplier whether i t is being used to cook your dinner or charge your car.

This probably explains a lot of the official enthusiasm for the hydrogen ec onomy.

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Bill Sloman, Sydney
Reply to
bill.sloman

c weight H is 1.008.

energy distribution network, and shipped through natural gas pipe lines.

water gets turned energy that can drive your car.

attery.

er to battery driven electric cars, about twice as much generating capacity as we've got if we went over to electrolysis-fed hydrogen-powered cars.

ing authority, is that hydrogen is going to be sold at refueling stations a nd can be taxed a whole lot more heavily than the regular electricity that is supplied by the grid, and looks exactly the same to the supplier whether it is being used to cook your dinner or charge your car.

economy.

Industry and government are not exactly remaining idle in tackling the chal lenges impeding wide scale adoption of hydrogen fuel, which has twice the e nergy density of fossil fuel btw. The big lure of hydrogen is that so much of the existing infrastructure for fossil fuels can still be used. As for h ydrogen production, many options other than electrolysis are being develope d. Apparently, massive development of renewable energy brings with it massi ve surplus energy production that can be used for hydrogen production. Look s like steam reforming of methane produces the bulk of hydrogen used today.

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bloggs.fredbloggs.fred

The last one of those I went to in the UK - in Trafalgar Square was powered entirely by smelly noisy diesel electric generators whilst pristine fuel cell systems were being displayed on the stands. Not a one of the commercial fuel cell systems were actually running to make power. (and some were theoretically capable of running a phone exchange)

The only ones running were demo toy ones for educational use in schools.

Big snag with fuel cells is that they are expensive and have a very bad tendency to get the catalyst poisoned if the hydrogen isn't pure enough.

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Carbon monoxide is an all too common trace impurity in the air.

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Regards, 
Martin Brown
Reply to
Martin Brown

Sulfur is another one. Your cite is quite old, a lot of work has since been done to significantly mitigate the problem, it's no longer a deal breaker.

Reply to
bloggs.fredbloggs.fred

The fuel cell was invented in 1838. Of course a lot of work has since been done.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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John Larkin

Are you sure about that? You might want to read up on Hydrogen embrittlement of steel. They'd have to run very high pressure on a gas pipeline to get much Hydrogen delivered.

Also, not so sure the turbine compressors (that burn natural gas) can be run off Hydrogen.

Jon

Reply to
Jon Elson

Yes, the gasoline engine is much newer. It's only been improved because users will buy the better equipment, as in any industry. "Build it and they will come".

But the BEV is also improving greatly. It's already good enough to sell by the 100's of thousands and it won't be too long before it is sold in the millions.

Rick C.

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gnuarm.deletethisbit

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Transmission pipelines run at 200 to 1500psi - from 13 to 100 atmospheres - which isn't a very high pressure.

Hydrogen has a slightly lower calorific content per mole than methane, but you wouldn't need to up the pressure much to compensate - if you were allowed to compensate that way, which seems very improbable.

So they'd need to be reworked. Fuel cells are the preferred way to burn natural gas, but the economics of the transition are likely to be messy.

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Bill Sloman, Sydney
Reply to
bill.sloman

Does it flow faster at the same pressure differential due to lower density?

If hydrogen appoches the molar energy of methane it should produce the same mechanical power with a leaner charge as it needs much less oxgen per mole

--
  When I tried casting out nines I made a hash of it.
Reply to
Jasen Betts

Some reports of its atomic weight in the UK remarkably found it to be

8.10.

Terry, East Grinstead, UK

Reply to
Terry Pinnell

The viscosity of all gasses is much the same, and pretty much independent of pressure. Look up your universal gas theory.

So what.

You can look up the enthalpy of the reaction of hydrogen with oxygen to produce water, and for the reaction of methane with quite a lot more oxygen to produce two molecules of water and one molecule of carbon dioxide.

In a fuel cell that's what happens and you get most of the enthalpy out as electrical energy.

Burning hydrogen or methane means that you are stuck with the Carnot cycle, and you can't extract as much of the chemical energy as useful work.

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Bill Sloman, Sydney
Reply to
bill.sloman

Transmission pipelines run at 200 to 1500psi - from 13 to 100 atmospheres - which isn't a very high pressure.

Enough to allow hydrogen to diffuse into and through steel.

Hydrogen is about 20% lower friction than methane. Very probably the gas with the lowest dynamic friction of all (ie the smallest molecule).

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The big noble gas atoms have amongst the highest dynamic friction.

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Regards, 
Martin Brown
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Martin Brown

{ about hydrogen gas in pipelines]

Hydrogen viscosity is about half that of air. Hydrogen is a light molecule, with high drift velocity, and that does matter.

Reply to
whit3rd

:-)

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Clive
Reply to
Clive Arthur

But 80% of that of methane, which is the relevant comparison.

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gives lots of primary data.

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is more accessible.

Hydrogen being light, with a high drift velocity, is a feature it shares with helium. Oddly, the viscosity of hydrogen is 0.84 at zero Centigrade and helium. is 1.87.

Benzene, which is a much heavier molecule, has an even lower viscosity, 0.7.

The deviations from universal gas theory can be counter-intuitive.

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Bill Sloman, Sydney
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bill.sloman

shares with helium. Oddly, the viscosity of hydrogen is 0.84 at zero Centigrade and helium. is 1.87.

Maybe it is "odd" because hydrogen is a molecule (unless in a plasma) whereas helium is atomic, being "noble".

Mike.

Reply to
Mike Coon

There is actually quite an elaborate pile of theory that pulls all of this together. I haven't had to worry about it for some fifty year now, so my grasp of it is imperfect.

I was merely pointing out that whatever "theory" whit3rd had in mind it wasn't a good one. You snipped the line about benzene vapour (without marking the snip), and decided to introduce you own equally half-baked theory.

The noble gases Helium - 1.87, Neon - at 2.98 - Argon - 2.1 and Xenon - 2.12 present their own bizarre sequence.

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Bill Sloman, Sydney
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bill.sloman

Car and Driver is always fun.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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John Larkin

It's not very elaborate actually.

Temperature is a measure of average molecular kinetic energy involved in surface impacts.

Ke = 1/2 m v^2

So at a given temperature (Ke) a gas with a lighter (m) molecule has a higher v. That affects speed of sound, dispersion, etc.

The hydrogen molecule is half the mass of a helium molecule, so the velocity at the same temperature is about 1.4 times.

Note that molecules (except for single atoms) also carry kinetic energy in the form of angular momentum, and the particular shape and moments of the molecule determine how much that affects the surface impact energy (temperature). Thus different molecules behave differently under compression, related to the gamma of the gas. CO2 != H2O != H2 != He.

Clifford Heath.

Reply to
Clifford Heath

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