I will believe the Saudis don't see any upcoming problems with Ghawar when they cancel one of their projects due to low oil prices. If they continue to be full steam ahead with increasing their capacity then I think they are aware that Ghawar may not be as robust in 5 years time as they would like us to believe.
Posted: Wed Aug 18, 2004 6:15 am Post subject: [Hydrogen 6] Please help me if you can
Hi, First post, but I've been lurking for a few months.
I'm trying to do some serious calculations on why a transfer to hydrogen won't work, things like how much water will be needed, how much area for solar cells and so on.
Things I'm not interested in at this point is time, I'm only interested in what it would take, given that we have enough time, to transfer to a hydrogen based transportation system.
Trouble is I'm having a hard time finding solid numbers on a lot of things, so I'm asking you people, if you have good articles, or postings that I might not have seen (I have searched the archives, and read most post the last 2-3 months as they appeared).
The reason for this is partly because I want a better understanding of this myself, and partly because I have promised to provide such details at another board.
I think it's safe to say that I have read all the "usual" articles, Youngberg, FTW:s hydrogen fool-cells, "The Party's over" and so on, trouble being those don't really contain much in the sense of hard numbers, mostly just opinions. Which I myself find convincing, but I want more...
thanks in advance
Agren
Here's a good site that works out a lot of the implications and alternatives: link
He adresses the possibility of hydrogen in the "Energy Sources" chapter, near the botton. The relevant passages are this (sorry for the long post):
Hydrogen
The higher and lower calorific values of hydrogen are:-
Higher heating value (HHV) = 142 MJ/kg = 39.4 kWh/kg
Lower heating value (LHV) after latent heat is subtracted = 120 MJ/kg = 33.33 kWh/kg
The lower value is obtained by combustion in an engine. Hydrogen does not occur naturally and has to be extracted and processed before it can be used as a transport fuel.
There are four processes, viz.,
(i) Steam reforming of methane
(ii) Electrolysis of water
(iii) Compression
(iv) Cryogenic liquefaction.
These can be combined as: (i) and (iii) or (i) and (iv), or (ii) and (iii) or (ii) and (iv)
(i) Steam reforming of methane
Hydrogen can be extracted from methane by steam reforming in two stages.
2CH4 + 3H2O = CO + CO2 + 7H2 and CO + H2O = CO2+ H2
32 kg methane with 72 kg steam yields 16 kg H2 and releases 88 kg CO2, but the process is only 70%-90% efficient, so the yield is reduced to 12.8 kg. Assuming 80% efficiency, 2.5 kg methane (2.5 x 55 MJ = 137.5 MJ) is needed to yield 1 kg hydrogen (120MJ) while releasing 7 kg CO2. The 7 kg steam required contains 24 MJ total heat, bringing the input to 161.5 MJ/kg or 45 kWh/kg.
The equivalent power used to obtain the energy of 33.33 kWh/kg in the hydrogen is 45 kWh/kg and 7 kg of CO2 is released. Thus more energy is used to extract hydrogen from the methane than obtained in it.
While natural gas remains available it is more efficient to use methane direct and less carbon for the useful energy obtained would thereby be released. This does not appear to be a worthwhile option. A better option, if sufficient quantities of liquefied natural gas (LNG) will be imported, would be to transfer it directly from an ocean gas tankship to containers on road vehicles. This would avoid liquefying the gas a second time.
(ii) Electrolysis of water
Electrolysis can consume between 3.7 and 4.5 kWh/Nm3 of hydrogen, which taking the mean is gravimetrically 58.6 kWh/kg (Say 59)
(iii) Compression
The energy used to compress hydrogen to a suitable storage pressure is around 12% of the HHV or 0.12 x 142 MJ/3600 KJ = 4.7 kWh/kg (Say 5)
(iv) Liquefaction
For large scale plants the energy used to liquefy hydrogen is around 40% of the HHV or 0.40 x 142 MJ/3600 KJ = 15.8 kWh/kg (Say 16)
(ii) + (iii) 59 + 5 = 64 kWh/kg
(ii) + (iv) 59 + 16 = 75 kWh/kg
Equivalent quantity required for UK transport in 2002
Cars use compressed hydrogen (Honda) or liquefied hydrogen (BMW and GM) while aircraft will need to use liquefied hydrogen because of weight and space requirements.
An effective energy content of 120 MJ/kg H2, means that vehicle energy of 1600 PJ (equivalent to 38 million tonnes /annum of petrol and diesel) would require 13.33 x 109 kg H2/annum, while aircraft energy of 500 PJ (equivalent to 12 million tonnes of jet fuel) would require 4.16 x 109 kg H2/annum.
This works out at 13.33 x 64 x 109 = 853 TWh for compressed gas
and 13.33 x 75 x 109 = 1000 TWh for liquefied gas.
For aircraft it works out at 4.16 x 75 x 109 = 312 TWh
For the UK this means that to substitute for the current road and air transport fuel by hydrogen would require from 1165 TWh to 1312 TWh of electricity generation, compared to the total UK generation of 386 TWh in 2002.
While in the future a favoured minority will use hydrogen-propelled road vehicles, this would be such an inefficient use renewable electricity that road transport will be substituted by rail (which can use electricity directly in traction engines). The establishment of a global hydrogen infrastructure for air transport seems an impracticable prospect. A tripling of global air traffic envisaged by 2030 would require electricity generation of 7000 TWh to be able to substitute liquid hydrogen for 260 million tonnes of jet fuel, which by then will be unavailable in sufficient quantities.
Thanks!
The foolcells article i had read, the other ones were good, i remember looking at after-oil, but had forgotten about it...
If there is any interest I'll post my findings when i'm done, even though it will be like preaching to the choir...
This is no big news though, because anyone can build unmanned military toys. Only when manned H airplanes are built, big enough to carry hundreds of passangers, will we be interested again in hydrogen airplanes.
Joined: Mar 04, 2005 Posts: 2729 Location: New Zealand
Posted: Tue Jun 27, 2006 9:26 pm Post subject: A Hydrogen Suitcase
A Hydrogen Suitcase
Quote:
In the 21 June issue of Journal of the American Chemical Society, Angela Leuking, a chemical engineer in the Department of Energy and Geoenvironmental Engineering at Pennsylvania State University in State College, and colleagues, describe a new, one-step process to both produce and store hydrogen.
As a first step, they put coal in a mill along with some steel balls and a little cyclohexene as a lubricant. The mill spun the contents at 400 revolutions per minute, and the coal was gradually smashed into a powder by the steel balls. The researchers then put the powder in a thermogravimetric analyzer to let it release any contaminating gases that might have stuck to it before they added hydrogen, but they noticed something odd: The sample was losing a lot of mass. They sampled the gas it was giving off with a mass spectrometer and found, shockingly, that it was almost all hydrogen. When they examined the milled coal under a transmission electron microscope, they found little bits of diamond--a clue that hydrogen gas was present. (Hydrogen helps carbon turn to diamond at low pressures.) The team's best guess was that the pressure inside the mill had been high enough to force the cyclohexene to change chemically and give off hydrogen, which then was trapped by the coal.
sciencemag _________________ Human history becomes more and more a race between education and catastrophe. H. G. Wells.
Fatih Birol's motto: leave oil before it leaves us.
Posted: Sat Apr 28, 2007 6:50 am Post subject: THE Hydrogen Thread (merged) Part 2
tank cost will go down to at least 11$/kwh (if not 4-6$/kwh)
hydrogen cost will go down to 10ct/kwh (3,3$/kwh)
phone GE or Quantum if you don't believe it
and i will now begin my 3th holidays this year and burn 50liters of diesel + 500l of kerosin,
so that we see 5$/gasoline in USA soon
and step into a hydrogen world
your happy consumer
Joined: Apr 16, 2007 Posts: 218 Location: New Mexico
Posted: Sat Apr 28, 2007 7:34 am Post subject: Re: hydrogen will save the mobility
Harlequin wrote:
Isn't hydrogen energy negative? As in not a viable energy source?
Bingo. Hydrogen is a *system* energy source, where the car is the system. But it is by no means a global energy source, as are fossil fuels and nuclear fuel.
So, just as a battery must be charged from another source (at <100% EROI), so must the hydrogen used to fuel such a vehicle be generated using another source (again, at much less than 100% EROI).
Hydrogen is only a medium.
As are biofuel, compressed air, batteries, and ethanol.
So, take that fourth holiday, burn the petrol & kerosene. But then you have even less
Rather than looking for new technology for our automobile-driven society, maybe we should start thinking about societ will be without many automobiles. Think bikes, horses, and mules, sail power and railroads (coal, wood, and maybe electric, if we don't crash too hard.
Posted: Sat Apr 28, 2007 8:12 am Post subject: Re: hydrogen will save the mobility
its easy to produce hydrogen from salt water with renewable energy...
there are also other methods, like using solar energy concentrators
we likely get the 3$/kgr H2 with an GE electrolyzier
to make this all happen we haven to consume more,
we won't change the world, consuming less !
there is only one way:
to fight for grow !
now i am away
Last edited by bonjaski on Sat Apr 28, 2007 8:20 am; edited 1 time in total
Posted: Sat Apr 28, 2007 8:15 am Post subject: Re: hydrogen will save the mobility
Why are you killing Baby Jesus? _________________ "When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours." - Stephen F Roberts.
Joined: Apr 16, 2007 Posts: 218 Location: New Mexico
Posted: Sat Apr 28, 2007 8:43 am Post subject: Re: hydrogen will save the mobility
bonjaski wrote:
its easy to produce hydrogen from salt water with renewable energy...
there are also other methods, like using solar energy concentrators
we likely get the 3$/kgr H2 with an GE electrolyzier
to make this all happen we haven to consume more,
we won't change the world, consuming less !
there is only one way:
to fight for grow !
now i am away
Having worked for 12 years as a mechanical/project/thermal engineer building everyting from power systems to rockets to armor, to nuclear-powered ships, I know that the *only* thing that is "easy" about new technologies is mere act of saying they are. Talk is easy...the rest is full of tough battles and unforseen difficulties. And there are *always* unforseen difficulties.
Where does this "renewable energy" come from? How do we get it and feed it into out H20 Electrolyzers? How do we design, develop, and test these things.
Having worked on similar projects, I can tell you that *if* a large organization--not necessarily the whole nation, but at least a $100B/year org put its mind to it to create such an infrastructure, the H2 generators would take a minimum of three years to be at a technological readiness level to begin a low rate of initial production...to make sure they even work on a larger scale. Add five more years to begin scaling up production, and you are looking at 8 to ten years just to have an infrastructure for the hydrogen generation.
As for the "renewable energy"...well, that is little more than an invokation to a higher power. If you want to run hydrogen generators, you don't need feel-good, pollitically warm and fuzzy words. You need energy, any way you can get it, at an indefinitely sustainable level. In other words, sunlight and it's derivatives (wind, hydro, bio). And we do not have that energy infrastructure. So, if you want your hydro-car, you'd better get cracking!
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