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The Physics of the Hydrogen Economy
Spy der Mann writes "A Physics Today article entitled The Hydrogen Economy explores the possibility of using hydrogen as an energy source. The article explores the current methods, limitations, and the need for more research. For those wanting to point out the Hindenburg incident, the article doesn't talk about gaseous hydrogen only, but also about hydrogen fuel cells. My favorite quote: 'The natural world began forming its own hydrogen economy 3 billion years ago, when it developed photosynthesis to convert CO2, water, and sunlight into hydrogen and oxygen'. Interesting read for eco-fans."
A friend and coworker was describing a scene he witnessed at a plant that liquifies gasses. You figure out which one.
One of his coworkers was pushing a metal cart loaded with a test rig down an aisle. About halfway down there was a huge *whump* that echoed down the hall and the entire front half of the cart was in flames. The man wasn't seriously injured, even being so close to a tremendous fire.
A H2 pipeline had ruptured (H2 embrittlement I think he said) and was spewing a steady stream of the material in a jet across the walkway. Somehow it had caught fire and, since H2 burns colorless no one saw it.
Had that cart not been there.... ouch.
Hydrogen is an integral component of dihydrogen monoxide
Is it just me, or should there be a distinction between "energy source" and "fuel?" If you burn gasoline, hydrogen is still the component providing the energy. So talking about using pure hydrogen versus hydrogen bound up with carbon (and other atoms) is a difference in fuel makeup than the energy source.
Or so it seems to me...
The Spoon
Updated 6/28/2011
Hydrogen is energy storage and transfer medium, not a power source. At least not in what is generally called "hydrogen economy". It takes a lot of energy to make Hydrogen (H2) in large amounts, and only quita s small portion of that "original" power is regained when the Hydrogen is later used as fuel.
Of course fusion power would use Hydrogen as power source, but that's a totally different issue, and it happening is probably much farther in the future than "Hydrogen Economy"...
Hydrogen is a Boondoggle. The energy density is so low, that we might as well use batteries if we're going to power vehicles with it. (It may be good for stationary purposes.) If we really wanted to, we could convert all US vehicles to diesel, and run them all with Algae-Derived Biodiesel using sewage as a feedstock. Because of the greater efficiency of algae, supplying all of our vehicular needs is actually feasible.
This would alleviate both the global warming problem and our dependence on Middle-Eastern petroleum. The technology is available now, and because of the high energy density, no sacrifices on the part of automotive consumers are required in terms of range and performance. (We may need to invest in research into better catalytic converters and turbocharging technology.)
The article isn't about how wonderful the hydrogen economy will be etc. etc. Nor is it about the Hindenburg. It's about the immense basic science challenges that will likely prevent any commercial viability for decades...
Given that the article was directed at research physicists (readers of Physics Today), the intent was probably to motivate people to look into these challenges as basic science research areas for their labs.
The main reason they think there's any point at all is because of the energy conversion efficiency of fuel cells, and the natural link between fuel cell use and hydrogen. But as the original post implies, one of the best ways to store hydrogen is in the form of hydrocarbons:
Energy: time to change the picture.
OK Since I'm the one who submitted the article, please allow me to clarify some logical errors in your statements.
,insert the electrodes, add some acid as catalyst, and plug the wires into a battery. Voila! Oxygen in one, hydrogen in the other. Now Try making oil from wood with your chemistry kit.
So, in order to have a large-scale hydrogen "economy", you need an alternate power source to make all that hydrogen in the first place.
News for you. Hydrogen is not "made". It's extracted. OK, putting the word jokes aside, I understand that what you mean is that *PURE* hydrogen is not found *NATURALLY* on Earth.
So we need an ALTERNATIVE power source to obtain it. So what? Electricity is not energy either! It's a bunch of electrons and possitive ions waiting for us to mix them together. We use turbines in dams to produce it. (kynetic energy -> electrical energy). We need engines (kynetic->chemical) to take out the oil from the deposits below Earth.
Didn't you study physics in high school? Just climbing some stairs transforms the kinetic energy you use to move, into "potential energy". And by falling you turn it into kinetic energy, too. And guess what, we're made of protons,electrons and neutrons, and all of these are made of quantums, which are discrete packets of *energy*.
EVERYTHING's energy, dude! So what's the mystery if hydrogen needs some alternate energy to be extracted from water or other compounds? Don't forget your thermodynamics lessons from college. All engines do is transforming one form of energy into another. And since no engine is 100% efficient, then we have what is known as "entropy", which constantly is increased across the universe.
So, what power source can we have to extract pure H2 from other materials? Well, we can have, for example, solar power.
Hydrogen can be built *instantly* with some electrolysis (either chemically or solar powered). I did it myself at home when i was a kid. You put these water-filled tubes in a bucket (upside down)
The H2-generating process is sub-optimal right now (as was the vacuum tube in the 70's to act as a current switch), but technology always improves with time. And don't forget that big companies like Shell are investing millions of dollars into research.
The point with using hydrogen, is that:
a) It's combustible and can produce energy when reacting chemically with other elements/compounds.
b) Unlike fossil fuels, it doesn't require millions of years to be produced/extracted/whatever.
c) It's clean, it doesn't produce CO2 when burned.
Did you RTFA by the way? How do you think fossil fuels are made? Plants transformed H2O + CO2 + SOLAR POWER + nutrients into wood (and O2 as a byproduct). And these with time were transformed into hydrocarbons. Which consist of long hydrogen and carbon chains (not to be confused with carbohydrates - sugars -, which have oxygen in them).
The real energy in hydrocarbons is stored in the chemical bonds between the carbon and hydrogen atoms. By burning them, the combustion process releases these bonds. O2 + (long chains of C + H) ---> H2O + CO2. See? There's the hydrogen, and the C. What we're wanting to do, is get the carbon out of the equation. O2 + 2H2 ---> 2 H2O.
So, is hydrogen economy all that far-fetched? No, it isn't! We've been using hydrogen in our cars for a lot of time. The problem is that we're also using carbon.
Frankly, I'm amazed why your post was moderated as "insightful" (someone MOD it as overrated, please!). More mysterious than the universe is the human ignorance.
P.S. If this post is modded up, please do so as "informative".