How much hydrogen is needed for an average fuel cell car, to run for say a week?
How much hydrogen is needed for an average fuel cell car, to run for say a week?I understand that the Enthalpy of Hydrogen is about three times that of petrol. You would need about one third of the mass of Hydrogen, compared with the equivalent mass of petrol. That only offsets, by a tiny amount, the overhead involved with storing hydrogen in a stable form. The best that has been achieved has been about 6% by mass. That means you would still need to carry around about four times the extra mass of the (very expensive) storage medium. This compares badly with the mass of a petrol tank. The medium can be easily contaminated by an impure hydrogen supply. Also, I should imagine that re-charging would take a lot longer than just pouring 40litres of petrol into your tank.
I understand that the Enthalpy of Hydrogen is about three times that of petrol. You would need about one third of the mass of Hydrogen, compared with the equivalent mass of petrol. That only offsets, by a tiny amount, the overhead involved with storing hydrogen in a stable form. The best that has been achieved has been about 6% by mass. That means you would still need to carry around about four times the extra mass of the (very expensive) storage medium. This compares badly with the mass of a petrol tank. The medium can be easily contaminated by an impure hydrogen supply. Also, I should imagine that re-charging would take a lot longer than just pouring 40litres of petrol into your tank.
We have some way to go, yet but, when it can be made to work, it will be very clean - but not a free energy resource.
In energy storage applications, the energy density relates the mass of an energy store to its stored energy. The higher the energy density, the more energy may be stored or transported for the same amount of mass. In the context of fuel selection, that energy density of a fuel is also called the specific energy of that fuel, though in general an engine using that fuel will yield less energy due to inefficiencies and thermodynamic considerations—hence the specific fuel consumption of an engine will be greater than the reciprocal of the specific energy of the fuel. And in general, specific energy and energy density are at odds due to charge screening.
Gravimetric and volumetric energy density of some fuels and storage technologies (modified from the Gasoline article):(Notes: Some values may not be precise because of isomers or other irregularities. See Heating value for a comprehensive table of specific energies of important fuels. The symbol ** indicates the item is an energy carrier, not an energy source.)
**mass-energy equivalence 89,876,000,000 **binding energy of helium nucleus 675,000,000 8.57x1024 nuclear fusion of hydrogen (energy from the sun) 300,000,000 423,000,000 nuclear fission (of U-235) (Used in Nuclear Power Plants) 77,000,000 1,500,000,000 30% 50% **liquid hydrogen 143 10.1 **compressed gaseous hydrogen at 700 bar 143 4.7 **gaseous hydrogen at room temperature 143 0.01079 beryllium (toxic) (burned in air) 67.6 125.1 lithium borohydride (burned in air) 65.2 43.4 boron (burned in air) 58.9 137.8 compressed natural gas at 200 bar 53.6 10 gasoline 46.9 34.6 diesel fuel/residential heating oil 45.8 38.7 polyethylene plastic 46.3 42.6 polypropylene plastic 46.3 41.7 gasohol (10% ethanol 90% gasoline) 43.54 28.06 lithium (burned in air) 43.1 23.0 Jet A aviation fuel 42.8 33 biodiesel oil (vegetable oil) 42.20 30.53 DMF (2,5-dimethylfuran) 42 37.8 crude oil (according to the definition of ton of oil equivalent) 41.87 37 polystyrene plastic 41.4 43.5 body fat metabolism 38 35 22-26% butanol 36.6 29.2 LPG 34.39 22.16 **specific orbital energy of Low Earth orbit 33 (approx.) graphite (burned in air) 32.7 72.9 anthracite coal 32.5 72.4 36% silicon (burned in air) 32.2 75.1 aluminum (burned in air) 31.0 83.8 ethanol 30 24 polyester plastic 26.0 35.6 magnesium (burned in air) 24.7 43.0 bituminous coal 24 20 PET pop bottle plastic ?23.5 impure ? methanol 19.7 15.6 **hydrazine (toxic) combusted to N2+H2O 19.5 19.3 **liquid ammonia (combusted to N2+H2O) 18.6 11.5 PVC plastic (improper combustion toxic) 18.0 25.2 sugars, carbohydrates & proteins metabolism 17 26.2(dextrose) 22-26% Cl2O7 + CH4 - computed 17.4 lignite coal 14-19 calcium (burned in air) 15.9 24.6 dry cowdung and cameldung 15.5 wood 6–17 1.8–3.2 **liquid hydrogen + oxygen (as oxidizer) (1:8 (w/w), 14.1:7.0 (v/v)) 13.333 5.7 sodium (burned to wet sodium hydroxide) 13.3 12.8 Cl2O7 decomposition - computed 12.2 nitromethane 11.3 12.9 household waste 8-11 sodium (burned to dry sodium oxide) 9.1 8.8 iron (burned to iron(III) oxide) 7.4 57.9 Octanitrocubane explosive - computed 7.4 ammonal (Al+NH4NO3 oxidizer) 6.9 12.7 Tetranitromethane + hydrazine explosive - computed 6.6 Hexanitrobenzene explosive - computed 6.5 zinc (burned in air) 5.3 38.0 Teflon plastic (combustion toxic, but flame retardant) 5.1 11.2 iron (burned to iron(II) oxide) 4.9 38.2 **TNT 4.184 6.92 Copper Thermite (Al + CuO as oxidizer) 4.13 20.9 Thermite (powder Al + Fe2O3 as oxidizer) 4.00 18.4 **compressed air at 300 bar 4 0.14 ? ANFO 3.88 hydrogen peroxide decomposition (as monopropellant) 2.7 3.8 Lithium Thionyl Chloride Battery 2.5 Regenerative Fuel Cell 1.62 **hydrazine(toxic) decomposition (as monopropellant) 1.6 1.6 **ammonium nitrate decomposition (as monopropellant) 1.4 2.5 Molecular spring ~1 **sodium-sulfur battery ? 1.23 ? 85% **liquid nitrogen 0.77 0.62 **lithium ion battery 0.54–0.72 0.9–1.9 95% **lithium sulphur battery 0.54-1.44 ? kinetic energy penetrator 1.9-3.4 30-54 5.56 × 45 mm NATO bullet 0.4-0.8 3.2-6.4 **Zn-air batteries 0.40 to 0.72 ? ? ? **flywheel 0.5 ? ? 81-94% melting ice 0.335 0.335 **zinc-bromine flow battery 0.27–0.306 **compressed air at 20 bar 0.27 ? 64% **NiMH Battery 0.22 0.36 ? 60% **NiCd Battery 0.14-0.22 ? ? 80% **lead acid battery 0.09–0.11 0.14–0.17 ? 75-85% **commercial lead acid battery pack 0.072-0.079 ? ? ? **vanadium redox battery .09 .1188 ? 70-75% **vanadium bromide redox battery .18 .252 ? 81% **ultracapacitor 0.0206 ? ? ? **ultracapacitor by EEStor (claimed capacity) 1.0 ? ? ? **supercapacitor 0.01 ? 98.5% 90% **capacitor 0.002 ? ? ? water at 100 m dam height 0.001 0.001 ? 85-90% **spring power (clock spring), torsion spring 0.0003 0.0006 ? zero point energy 0 0
There has been a new fuel cell technology developed. It uses a hydrogen compound that is liquid at room temperature and doesn't require the expensive platinum catalyst. I don't recall the details.
With a hydrogen fuel cell, the chemicals are hydrogen and oxygen, and they are continually fed to the fuel cell, so they do not run out (or, if your tanks run dry, you just fill up with more hydrogen, but you don't need to throw away the fuel cell).
So oxygen is used as well?Yes, it is crucial, but oxygen is readily available from the air, so you don't need to tank up on it.
It's a hydrogen oxygen liquid fuel mix?
Could you not also used liquid helium, or nitrogen? With transfer of electons, surely any Gas atom could be used.
Is this the silly season for nakedscientist forums?
Doesn't anyone read books before starting to post here?
So oxygen is used as well?Yes, it is crucial, but oxygen is readily available from the air, so you don't need to tank up on it.It's a hydrogen oxygen liquid fuel mix?
The hydrogen and oxygen are stored separately. To premix them would have a dangerously explosive mix, and would anyway have to be separated when entering the fuel cell. In any case, as I said, for most applications, you don't need to carry your own oxygen (it is normally available from the air around you - unless you are looking for applications in space, or submarine applications).
As for whether the hydrogen is liquid - cryogenically stored liquid hydrogen is one choice, so is high pressure gas storage, and so is gas absorption in some solid matrix. Each solution has its own problems.Could you not also used liquid helium, or nitrogen? With transfer of electons, surely any Gas atom could be used.
No, it depends on the structure of the electrons around an atom. All atoms are naturally electrically neutral (i.e. the number of positively charged protons in an atom normally balances the number of negatively charged electrons), so there is good reason not to give away or accept another electron, since that would make them no longer electrically neutral. On the other hand, atoms also like to have certain specific configurations of electrons around them in preference to other configurations, and if they have too few or too many electrons for their ideal configuration, then they may give up or accept another electron in order to obtain an ideal configuration. When you get an atom that has too many electrons for its ideal configuration, and one that has too few electrons for its ideal configuration, then the one that has too many electrons will give away its electron, and the one that has too few will accept an electron, and between them you will get a stable chemical compound (that, in a nutshell, is the basis of all chemistry).
The first rule is that electrons like to go around in pairs. Normal helium has exactly two electrons, and so for it, that is an ideal number of electrons, and so it will have great difficulty either accepting another electron or giving up an electron.
For oxygen, it naturally has 8 electrons, but the ideal number of electrons for an atom of about oxygen's size is 10 electrons. Neon is slightly heavier than oxygen, and has 10 electrons, and so, like helium, neon is very difficult to make chemical compounds with.
Hydrogen would really like to have 2 electrons (like helium, its heavier cousin), but it will just as readily give up its one electron, so it has no electrons.
If you then have two hydrogen atoms, each willing to give up one electron, and one oxygen desperately seeking to get two more electrons, you can see they are in a strong position to make a swap - and between them make a chemical compound of two hydrogen atoms and one oxygen atom - this compound is water.
Could you not give helium an extra electron? Or is that what helium 3 is?
So the trick really is to make a electron full store of hydrogen to put in your car. Could you not, return the hydrogen to the fuel cell after use, by running it through a coil where it could pick up more electrons?
As you say, both of these feedstocks contain carbon, and so will produce carbon dioxide, but since both can (and often are) created from plant matter, thus the carbon dioxide created is from carbon dioxide taken from the atmosphere (true, the same can be argued for mineral oil combustion, but in the case of mineral oil, the counter argument is that it was taken from the atmosphere millions of years ago, whereas boifuel sources of methenol or methane could be take from the atmosphere with the preceding 12 months).
The arguments about efficiency are far more complex that that stated.Naturally it is. I'm not saying that you can achieve 90% net efficiency and comparing this to 20% efficiency in a diesel engine. I'm just saying, that the potential of a fuel cell powered vehicle exceeds that of a diesel powered vehicle. But both methanol and diesel synthesis/refining requires energy, so you'd have to do an extensive energy calculation to find the pro's and con's. My point in the efficiency is therefore only referred to the engine (as i do not have the results from that calculation) And one thing, that you can not get around is, that the efficiency of a combustion engine is limited by the fact that it is a Carnot engine (and there limited by its operating temperature and surroundings temperatures), whereas the fuel cell is only limited by the free energy of the fuel (which is about 90% of the total enthalpy in the hydrogen). Naturally you have to account for the electric motor as well, which i do not have confirmed figures for, but a quick google search tells me, that a 100 hp electrical engine is able to do +90%. Mechanical resistance can be assumed to be the same for the two vehicles (though I'd expect a combution powered vehicle to be even more inefficient due to shafts etc etc.)
I don't really get the it takes energy to produce it arguement, it takes a huge amount of energy to produce petrol surely.
And helium as a fuel, could be, or would be, highly volitile?
Hydrazine hydrate—a compound of nitrogen, hydrogen, and water—is liquid, which makes it easier to store and deliver than gas. And it contains no carbon, so cars using it would still be environment-friendly. But perhaps the main advantage of the new fuel cell is simply that it's cheaper.
I don't really get the it takes energy to produce it arguement, it takes a huge amount of energy to produce petrol surely.
As SJoeberg has mentioned, it is all about how much you spend for how much you get.
Think of energy as money (very much, energy is the currency of science).
If you spend £1 million, and get £2 millions back, you are in profit, and it is a good deal. If you spend £1 millions pounds, and get only £1 million back, you have achieved nothing, and by the time you have paid your brokers commission (because all real life processes have inefficiencies that lose energy beyond the theoretical ideal), you will actually have made a small loss - certainly not the kind of deal you want to make.
Yes, it does take a huge amount of energy you have to put in when processing petrol; but in that particular case, the amount you get back exceeds what you put in, so you are in profit.
Hi all, been reading this forum for a while. Decided to register and post.
I have been reading a lot about hydrogen electrolysis and maybe some people here could provide some additional input. I have plans to build a gas-saving device for my car.
This device supposedly injects hydrogen into the vehicle's intake manifold in order to allow for a decrease of gasoline consumption on some level or another. It does this by allowing the engine to burn hydrogen in the combustion chamber along with the existing gasoline and oxygen mixture. Supposedly, doing so will allow an engine to run at a max of 30:1 air/fuel ratio (hydrogen being included in the air part of the ratio). That's pretty lean. Supposedly it can double gas mileage. It's just an electrolysis device that creates hydrogen ions from water. I'm not exactly sure how much hydrogen must be electrolyzed, how existing fuel management must be modified, or how much energy it would take to do so, so have not been able to figure out if the task would be worthwhile. There are claims that it does work, such as this: http://waterpoweredcar.com/hydrobooster.html
What do you think?
You don't need to worry about trying to store hydrogen in gas form, using pellets made of an alloy of aluminium and gallium, you can just store a tank of water in your car, and add the water to these pellets which reacts and turns the aluminium into aluminium oxide, and produces hydrogen. This way you get hydrogen on demand, without storing anything at high pressure. Then once you've exhausted your aluminium you get some more, and recycle the aluminium oxide. The gallium is not used, it is just a catalyst, normally aluminium will not react with water because an oxide layer forms over the surface of the aluminium protecting the rest of it from oxidising, but this does not happen when alloyed with gallium.
read about it here http://www.physorg.com/news98556080.html
"Most people don't realize how energy intensive aluminum is," Woodall said. "For every pound of aluminum you get more than two kilowatt hours of energy in the form of hydrogen combustion and more than two kilowatt hours of heat from the reaction of aluminum with water. A midsize car with a full tank of aluminum-gallium pellets, which amounts to about 350 pounds of aluminum, could take a 350-mile trip and it would cost $60, assuming the alumina is converted back to aluminum on-site at a nuclear power plant.
"How does this compare with conventional technology? Well, if I put gasoline in a tank, I get six kilowatt hours per pound, or about two and a half times the energy than I get for a pound of aluminum. So I need about two and a half times the weight of aluminum to get the same energy output, but I eliminate gasoline entirely, and I am using a resource that is cheap and abundant in the United States. If only the energy of the generated hydrogen is used, then the aluminum-gallium alloy would require about the same space as a tank of gasoline, so no extra room would be needed, and the added weight would be the equivalent of an extra passenger, albeit a pretty large extra passenger."
Drastic times call for drastic measures man. We've done a hell of a lot to mess up the atmosphere, it makes sense we're going to have to put a hell of alot of energy into fixing it.
Burns hydrogen instead of oil. So you can fill your car up with water, and only oxygen comes out the back.
Actually, I saw a commercial for this on TV, they said water vapor comes out which I find hard to beileve cause I thought we were years away from these things.
Is this the silly season for nakedscientist forums?
Doesn't anyone read books before starting to post here?
Hi there,
I think this information may help you out
Have you ever heard of HHO fuel that has got to be the best way to save on gas prices.?
? Imagine the savings. It will cost you about $160, or two tanks of gas to install an HHO
conversion kit
<Hydrogen Car Kit - Save Money and Improve MPG Massively
Hydrogen car kit empowers your car to run on water and avoid oil as fuel. A vehicle however
will not be able to run on water alone. There needs to be a mixture of gasoline and water to
enable it to run smoothly.
Even the Water Fuel Conversion Kits - How Using Water As Fuel Helps Cut Your Gas Consumption
Recently,there is increased awareness among many drivers of a technology that uses plain
water tosupplement the cars' gasoline consumption. Called a water fuel conversion kit, it is
a simpleadd-on to your current car engine that uses your car battery to carry out an
electrolysis on water to produce Hydroxy gas (HHO). This Hydroxy gas is used to supplement
the burning ofgasoline in the car's engine.
Hydrogen generator kit for car can be better than gasoline or oil additives to raise gas
mileage. When you make or do it on your own, you can save money on gas but will save lots
of dollars on the kit and reproduce the system for other automobiles on your own.
saving money should be what everyonr thinks off and I have done this by using all ideas from
my free Ebook -******
I purchased the available eBooks that teach you how to run your car on water and installed
one on my "chevy 350 small block," it's pretty easy.
<******* This reads too much like an advert so I have removed the link. Hope you don't mind. People can send you a personal message if they want the booklet.
Mod>
Oh, by the way, Sophie, you have joined the ranks of the 'Big Oil Conspiracy'(according those who believe there is one) by editing that link.??? I just removed what looked to be an advert.
QuoteOh, by the way, Sophie, you have joined the ranks of the 'Big Oil Conspiracy'(according those who believe there is one) by editing that link.??? I just removed what looked to be an advert.
Of course there is, or has been, a 'Big Oil Conspiracy', just as there are Pharmaceutical, Political and Financial Conspiracies. But now the Energy system is changing there is money to be made elsewhere and there will probably be a 'Green Conspiracy'.
How can you expect any large organisation not to promote its own interests in any way that it can?
Thanks to the relative freedom of information, conspiracies are often exposed, tho'.
Was I just being dim there and failed to spot a joke?
There's one born every minute.
Yes but that assumes that they are all mugs (Barnum's(?) original quotation referred to mugs, I believe). Your calculation implies that one in six of us is a mug. Let's see - there's you and there's me - not mugs. . .It took many centuries to reach one billion, only one century for the next billion, and less than one century for the next five billion.
Now count the conspiracy theorists, on the other hand.
As one of "those skeptics", I must point out that many of us are perfectly willing to accept this theory if we could see a working model. There are endless numbers of "how-to" CDs, books, and E-books, but nobody willing to actually demonstrate that this technology is anything more than a scam publicly.
The concept of running water as fuel for cars has been something scientists and researchers have been attempting for quite some time. With the high fuel prices as well as the pollution being an ever-increasing concern, the idea of water grows in the minds of these scientists and researchers. As the process continues for them to successfully create fuel from water the exhausting fact that it just isn’t working has them somewhat baffled.
Although many experts claim that water can in fact be used there are those skeptics who believe it is impossible. However, in all fairness water does in fact contain hydrogen and hydrogen of course is a form of gas.
You can avail e-books on water fuel at
Interesting that this 'scientific miracle' has never been seen publicly. Everyone has a book, CD, or E-book on their website, but nobody in the auto or parts industries can recall ever seeing one.
One design I've looked at uses stacked stainless plates with power and ground attached every 5 to 6 plates, allowing a gradual voltage drop across each plate, and is reported to produce less heat. I"m cosidering one of these type units or using a step down transformer to reduce voltage and increase amperage.
My Land Rover is a V6, but I assume that you understand that an electrolyser will never make enough gas to run and ICE. The best I can hope for is it to act as a booster and improve the mpg and by what degree I would guess depends on how much gas I can produce.That's basicly what we are looking at this point. Except for 1.5 volts per plate you will have to add one. A fulling charged battery is 12.6 volts, but your alternator runs in the mid 13's, almost 14 1/2 volts at peak.From what I have read so far the most efficient splitting voltage per plate is 1.24 to 1.47 volts. We'll look in to it.
The thing is, a poorly designed electrolyser will make the alternator work harder than it has to in achieving a any given gas output.
Electrolysers are more efficient when running hot, but regulating the temperature is going to always pose a problem, as even at low power, in a confined space the unit is likely to eventually start simmering. I'd rather err on the cool side than it boiling off. If anything a temp sensor to cut-off power supply just before the unit starts boiling would be advisable, but surface water will start to evapourate more readily well before the bulk of it boils.QuoteOne design I've looked at uses stacked stainless plates with power and ground attached every 5 to 6 plates, allowing a gradual voltage drop across each plate, and is reported to produce less heat. I"m cosidering one of these type units or using a step down transformer to reduce voltage and increase amperage.
The key is to tailor you're design to fit the applied voltage. If you're using a 12V car battery then ideally you want a 1.5 volt drop across each individual set of plates. So you would want the ground 0v on the cathode (plate 1), with 7 floating plates in between, and finaly the 12v +ve attached to the anode (plate 9). The potential difference (voltage drop) across each two plates is always 1.5 volts, and from ground to 12v +ve, relative to ground, reads:
plate 1 (cathode) 0v, plate 2 = 1.5v, plate 3 = 3v, plate 4 = 4.5v, plate 5 = 6v, plate 6 = 7.5v, plate 7 = 9v, plate 8 = 10.5v, and plate 9 (anode) = 12v.
As transformers are not 100% efficient you will only waste energy taking that route and it is not necessary if you use the correct plate configuration. Using the plate configuration above really is the best way to make the most of your given supply voltage.
To further up the efficiency of my figure 8 cell, I really need to add another 2 outer ss tubes as I'm only effectively using 7, so my voltage drop across each pair of tubes is 2v. But then it was originally just a test cell.
The most inefficient designs will only have an anode and a cathode, with the full 12 volts drop across just these two electrodes. And don't confuse multiple plates for floating plates.
It doesn't matter what design of electrolyser you use, power dissipated (heat) will always be dictated by the current x the voltage (IxV). You might have a well designed 9 plate electrolyser dissipating exactly the same as a two electrode unit, let's say 150 watts, the difference being that the 9 plate electrolyser will be producing a lot more gas! 8 x more to be exact!!