there has been increased talk about hydrogen powered fuel cells replacing gasoline internal combustion engines . This sounds really good, but can any body tell me where we are supposed to get all that hydrogen gas from ? It’s true that hydrogen is the most common element in the universe , but very little of it is useable , being already oxydized .
Fuel cells (which are what is used most commonly in hydrogen powered cars) they can use alcohol, natural gas or propane among a variety of substances. A reformer strips the hydrogen out of these sources. Oxygen from the air is then combined with the hydrogen to produce electricity and water is the exhaust. (Vary basically speaking)
Separate water into Hydrogen and Oxygen in bulk; the power from this could come from fossil fuels or sustainable sources.
Converting in bulk like this has two benefits:
[ul][li]If you’re burning fossil fuels to do this, it means you have several large sources of pollution (power stations) rather than several million small ones(cars) - it should be easier and more efficient to deal with the pollutants on an industrial scale.[/li]In theory, the conversion process could be more efficient when carried out in bulk.[/ul]
Hydrogen is manufactured even today. Common source of hydrogen is by steam reforming Natural Gas or Naphtha
CxHy + H20 --> CO + H2 (Balance the equation)
Then the shift reaction
CO + H2O —> CO2 + H2
Hydrogen manufactured today is used for making ammonia (for fertilizers), Hydrodesulfurization (To separate Sulfur from Petroleum), A variety of Catalytic Reforming and Polymerization reactions.
Hydrogen can also be made from Bio-fuels.
Remember that storing hydrogen is a hassle. Much more dangerous than gasoline. Not to mention that you dodn’t see many hydrogen refueling stations available. Fuel cells would be much more efficient if given pure hydrogen to work with but these days I think fuel cells need the hydrogen manufactured on the spot (getting your hands on natural gas isn’t too hard).
Making local hydrogen is not easy either. NASA has been trying that for ages, instead of getting their hydrogen from Louisiana.
Mostly small hydrogen generators use alkali metals in a recycle loop.
The coolest proposal I’ve seen is to put a ring of CANDU nuclear reactors near Yucca mountain. You’d need something like 174 nuclear reactors to make enough hydrogen to replace gasoline in the U.S. auto fleet.
The CANDU has some specific advantages that make it perfect for this use. First, they use heavy water as a moderator and coolant. That’s useful because the heavy water is a byproduct of hydrogen production through electrolysis. So in making the hydrogen, the reactors also make their own coolant and moderator. The entire cycle is very efficient therefore. Also, a CANDU cannot melt down, because the coolant IS the moderator. If the coolant stops flowing, the reaction shuts down automatically.
CANDU reactors can also burn spent fuel from other reactors. So putting them near Yucca mountain means that they can also act as a reprocessing facility for spent fuel from other reactors, making the fuel cycle even more efficient. And since they are near Yucca, transporting their waste for storage is simple and safe. BTW, the waste from a CANDU reactor deays back to the same level of radioactivity as the ore it came from in about 400 years.
So… You’d have lake Mead feeding water into these reactors, and then huge pipelines piping the hydrogen around the country where it could be distributed by local distribution centers or burned directly in city power plants.
If nuclear power is used you can get hydrogen without CO2
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All sites referenced above are in pdf. format.
I thought fuel cells for cars do in fact make their own hydrogen. I will grant that the hydrogen produced may not be as clean as what NASA would like for its uses but nevertheless it is done. It scares me to think of cars driving around with hydrogen storage tanks on board. Puncture the tank and you have a good chance for a major exlposion (more serious than a punctured gasoline tank).
Actually, there’s some evidence that hydrogen is safer than gasoline. Leaking hydrogen tends to dissipate. Leaking gasoline forms pools, and so stays dangerous for a longer period. Also, gasoline vapor is easier to ignite (i.e., ignites at a much lower density and at a lower ignition temperature) than does hydrogen.
I also recall, a few years ago, seeing film of people shooting bullets at hydrogen and gasoline storage tanks. I can’t vouch for the integrity of those demonstrations, but I recall that one of the points made was that a hydrogen explosion tended to disperse the unburnt fuel. Gasoline explosions tended to throw burning gasoline around the site.
On the contrary, hydrogen required in fuel cells is more “refined”. While rockets can do with some CO in the fuel, Catalysts in Fuel Cells are easily posoned by Sulfur and CO, and the like.
You can make hydrogen from Nuclear power, but even cheaper is hydroelectric power. In fact lot of third world countries used hydroelectric power to electrolyze water to hydrogen to make ammonia and then urea and the like.
There are many methods to make hydrogen. The safest, in my opinion, for H2 in fuel cell cars would be hydrogen adsorbed in suitable sintered metals.
I’m not sure about that.
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- I agree with the OP: “running everything off clean-burning hydrogen” is a dream; lots of people seem to miss the observation that if pure hydrogen was that easy to get in large quantities, we’d be using it already. There simply isn’t any other liquid or gas fuel that is as abundant and easy to obtain as petroleum.
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- Another good one is that “it costs more, but pollutes less”—uh, no. The cost of anything is typically liked very heavily to the amount of resources required to obtain it. So if a fuel-cell (or electric) car costs more to purchase and operate than a gasoline vehicle, then the fuel-cell/electric probably requires more resources to construct, and is very likely causing more pollution to be produced in the process.
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Not necessarily. There are dozens of factors that determine cost and not all are linked to the amount of resources necessary to manufacture it.
For instance, this is a new technology and the resources put into R&D to devlop it need to be recouped. Internal combustion and drilling for oil are old, established technologies. Fuel cells are new and getting the hydrogen necessary to run them is difficult. Imagine what it will take to put hydrogen refuelling stations on every corner in the US (not to mention the rest of the world). If not hydrogen then natural gas or whatever you use for fuel.
There’s also such a thing as economy of scale. If I ask you to build ONE widget for me it will cost a lot compared to having you build me a million widgets (that is, the cost per unit will decrease dramatically). If fuel cells become a viable technology that makes its way into every automobile built you will see the price drop big time.
NO, THEY ARE NOT. The first working fuel cell was made way before an IC engine. First Fuel Cell 1838 First IC Engine 1859
And about the Reformer. Its a very complex process system. A reformer is basically a furnace. You burn fuel through burners in a chamber (the burners can be on the side or the bottom) and use the heat directly on tubes carrying hydrocarbon/steam mixture to reform them. The reforming reaction takes place in the radiation zone with temp in the range of 1000deg. C. The convection zone is used to preheat the mixture. And there is a heat recovery zone to make steam an/or preheat the air going to the burner.
Its not a simple thing to build or operate. Just to start up the reformer takes a few days to a week (because of the thermal expansion of the tubes/supports in the radiation zone). Same time for shutdown. Also, the burners are special.
So if you have a reformer on a car, you’ll still end up giving off fumes.