Sure, it had a hairy reentry/recovery, but it certainly recovered samples from the inner Solar System. These were likely attributable to the Sun or were of interstellar origin.
http://en.wikipedia.org/wiki/Yavin...I mean, in the litany of famous gas-giants, this one certainly rates. Not much else could get between the rebels and the first Death Star.
Well, your comment is undoubtedly going to be a common one.
I was almost inspired to begin "Oh, please...", but I have to admit: I'm a technocrat at heart, and it's just a knee-jerk reaction.
Regarding Stern's Op-Ed, note that he was in SMD (Science Mission Directorate), a portion of NASA that routinely suffers cutbacks that reward "...the guilty" and punish "...the innocent," to borrow his phraseology, mostly in favor of the Manned Space Program.
The issue facing MSL is, indeed, endemic within the ranks of advanced "marquee" missions; furthermore, one cannot ignore the fact that it is easily the most advanced planetary surface mission conceived to date. It's likely some mismatch of management and planning has occurred.
The action to delay MSL's launch until the 2011 window, though, is a choice between following through on a bad bet vs. saving an good investment. It must be seen in light of what it represents: a decision to maximize a return on an already large investment of spent money instead of wasting it unwisely on unnecessary risk.
I'd like to second Colonel Korn on this one (I've certainly never written THAT before); the concept of reusable hydrogen storage materials is not a new one. It's devilishly difficult, of course, but not new. Check out http://hydrogen.energy.gov/ to see what's been done so far.
Buckyballs, like carbon nanotubes (CNTs) before them, store hydrogen by physisorption, whereby hydrogen molecules (not atoms, usually) "stick" to the near-surface via van der Waals forces (or equivalent). The issue with CNTs, of course, is that they really didn't do it as well as folks had hoped (or originally thought; there was some controversy over this). Overall, physisorption systems (the AD- vs. AB-sorption that the parent was referring to) don't do as well as chemisorption systems like metallic hydrides, though. The peak capacities are something like 3-6% vs. 12-15%, respectively.
But let's not mince words here; the real key issue in this case is that the nice folks at Rice have RUN A MODEL. They haven't done any empirical work to determine whether this actually works. If you've been keeping score here, that's where the rubber meets the road. Personally, I'm not holding my breath on the claimed 8% number.
After working in this field for a while, I've noticed that these kinds of claims appear at regular intervals (usually from universities with good media departments) regarding "miracle materials" that store tons of hydrogen. Don't get me wrong; any active thinking is progress - but let's be productively skeptical, eh?
To Rice's PR department: good show, but I don't buy it. Sorry for the cynicism.
I'd like to hope that the "geniuses" comment featured in the article post, but I honestly can't tell. I think some of the previous posts point out, better than I can, how unseemly sarcasm would be in this case.
For information on how successful the Ulysses mission has actually been, including its recent historic third pass over the north solar pole, Please refer to the Ulysses home page at JPL:
In any case, I'd like, perhaps, to suggest that the article post could either have been written, or otherwise reviewed, with more editorial skill. Then again, maybe that's asking too much. And that statement was not intended to be sarcastic.
I'll make the same pitch again for folks to drill down on the.gov hydrogen site; there's a lot of useful info there.
There are definitely more than one promising solid hydrogen carrier; hydride materials come in easily dozens of chemical families, about 5-10 of which are under considerable investigation.
There aren't as many options for a liquid carrier; there are (or rather, were) two general approaches if I recall correctly - one, an organic (i.e., carbon-based) carrier solution (a slurry, really) in which hydrogen would be soluble; the other, something like ammonia-borane or other N-B-H compounds, also liquid. The latter is, obviously, inorganic - but not trivial, since it might tend to release ammonia or borane products, both very bad things for fuel cells (not to mention people).
I think there's a lot of development in this area, but unfortunately I'm not terribly familiar with the chemistry, technically speaking.
If you're interested in this technology area, you can definitely start by following the.gov link in my post. Much of the published data produced by groups under the DOE funding can eventually be found there; there are annual reports and other such summaries.
Some pretty hard-core (but still interesting) stuff is at this link, for example; tech publications and such:
As for the idea of hydrogen dissolved in solid material, that technology area refers to "metal hydrides", which are metallic alloys and related compounds that - among other behaviors - can literally "soak up" gaseous hydrogen like a sponge. And many can do this at room temperature, at or under atmospheric pressure (read: relatively inert/safe).
You know nickel-metal-hydride (NiMH) batteries? Although this rechargeable technology is on the way out as Li-ion batteries mature, they contain exactly these kinds of materials. Metal hydride technology isn't so new, actually; the chemical effect has been known for, I don't know; something like 75 years or so. As a useful technology, though, it was the arms race (i.e., nuclear weapon research) that pushed the envelope in the 50s and 60s.
Hope that helps. As for "odorizing" the hydrogen, it's probably more preferable to employ sensitive detectors that will warn folks of an H2 leak long before their noses can. Never can tell, though.
Another Hindenburg reference. Great fricking Caesar's Ghost.
Seriously, though - and on a tangent for a sec - he's got a point. No, not about a hydrogen-fueled car ACTUALLY bursting into flames a'la the great Lakehurst weenie roast (that's why he used a smiley-face, I guess) but - unwittingly - about the public's perception of the implications of having hydrogen on-board a road vehicle.
The truth is, technology wants to go in a safer direction. The US DOE is spending a lot of money - well-spent, in my opinion - on developing components of an automotive approach to hydrogen fuels, including infrastructure, end-to-end efficiency and cost, and of course materials science and engineering.
The long and the short of it is this: the current standard is to store compressed hydrogen on-board in 5000 psig tanks; the tech maturation for this approach is to up the ante to 10000 psig. Yikes; no wonder the public has the wrong idea - that's a lot of mechanical energy stored up in there. Some of the more interesting (but not new) technology DOE is funding is for "absorptive" storage, both liquid- and solid-state, wherein the hydrogen isn't at high levels of compression - rather, it's safely (for the most part) tucked away inside the molecular structure of a parent "carrier" substance. At fairly low pressures (~15-150 psig), for the most part.
Okay, tangent over. In the interest of full disclosure, I am a hydrogen materials engineer. And I'm WAY more frightened of gasoline vapors than I am of hydrogen in any form.
Cheers - I thought I was the ONLY person who read all those books. Trying to explain them to most folks is a losing proposition; thanks goodness for Wikipedia. Poor Danny and his friends never had the clout of, say, the Hardy Boys.
But as far as I'm concerned, Irene Miller could beat the $#@! out of Nancy Drew.
The submitter makes it sound like a boast but in reality it's simply saying that enthusiasts will appreciate the reference.
You realize, of course, that my portrayal of Mr. Clarke's message said nothing about the monolith or his choice of Iapetus as its location. I was merely referring to the fact that, as is evidenced by the text of "2001", his physical description of Iapetus is eerily accurate for the time, all things considered. Believe me, that fact has given rise to more than one website's claim of conspiracy...
As for the perceived transitive nature of the verb "reminded"...actually, that's not how I meant it at all. I suppose I intended more to imply that the audience was reminded by inference, but in my excitement probably failed to make that clear. My bad.
I'm also with the poster that suggests that Clarke is due a little ego-stroking now and then...
Technically, the Mars Sample Return http://mars.jpl.nasa.gov/technology/samplereturn/i ndex.html is a precursor mission (i.e., before manned landings) that's been "on the books", so to speak, for a while. It's a developmental mission model, having been bounced back-and-forth between front and back burners for a while, now, but the technology is all there. It's very expensive, as you can imagine, so that's part of the reason why it's not "ready" yet. Other reasons have to do with local infrastructure - we'd like to have a handle on good surface communications on Mars - and the fact that the science community can't really decide on a reasonable surface target. That's being helped by MER, and will really get a good kick in the pants by the Mars Science Laboratory (MSL), which will be launching in 2009.
Of course, the public have very varied opinions about this...for example,when you Google "Mars Sample Return" you still get http://www.icamsr.org/ as your first hit. Sheesh.
Actually, there's some body of work that describes a larger problem for Lunar explorers, although the Martian problem isn't anything to sneeze at, either. Pun intended.
As TFA points out, the lack of weathering processes on Luna leaves the dust/regolith mainly as sharp-edged grains, which actually gives them incredible abrasive power. This poses an enormous problem for mechanical assemblies that have any wear surfaces. The Apollo astronauts, IIRC, went through a couple pairs of suit gloves each simply from the wear of the dust on their metallic glove locking rings.
Martian dust might have a similar range of effects, but I hadn't heard of the "toxic dust" issue, yet; that's the interesting bit. Silicosis of the lungs and related disorders, yes; toxicity, no. Yikes.
Toxic dust makes me think of the blended iPhone. "Don't breathe this." Sorry, that's another article...
Absolutely true - I was going to mention the bond energy of water (460 kJ/mol, if anyone cares - or is still reading this). Other than that, yes, the hydrogen storage density of water is quite high. Trouble is, the instant you remove a single hydrogen atom, you get hydroxide, which generally doesn't do nice things to fluid systems. The trick is removing both H atoms. It gets easier for the second one, which is nice.
However (and I don't remember exactly how), there are catalysis effects that promote water dissociation without high temperatures, for example, or other non-ideal processing steps. Gotta achieve the bond energy, though; that's still thermodynamics. But platinum, palladium, and others can be used (I think) to selectively sweep the hydrogen from the feedstock. You can do "photo-dissociation" too, IIRC.
While we're on the subject, how about some passive solar power, doing nothing but cracking water 24/7? I mean, we're going to have to get all this hydrogen from someplace...yeah, I know - takes a LOT of panel area.
I agree that it would appear they could be talking about Alane (AlH3), which has a theoretical weight-density of about 10% hydrogen. Yes, 10% is good...but as folks in the hydrogen storage community would be quick to tell you, it's not unusual. For example, Lithium Borohydride (LiBH4) has a theoretical weight-density of almost 18.5% hydrogen! The key is simply to bind hydrogen with light elements in a stable configuration, right?
Wrong. That's not even the tip of the iceberg.
The real problem, as any hydride person would correctly point out, is not "theoretical storage fraction"; rather, it's REVERSIBLE storage fraction. It doesn't really matter, in the long run, if you can store 18%, or even 25% hydrogen by weight in a substance if the following are true:
1. it takes a LOT of energy to put it in (theormodynamically unfavorable hydrogenation reaction) 2. you can only get out a small fraction of what you put in under favorable conditions (non-reversibility) 3. the reaction doesn't move very quickly (unfavorable kinetics)
With these limitations, you face a severe energy penalty for trying to use the material as a hydrogen carrier, mostly because it's one-way. The keys to an inexpensive, efficient solid-state hydrogen storage material combine high storage fraction with a high level of reversibility: why bother using a material if you have to ship it back to the "refinery" when the hydrogen has been depleted? As an example, let me use the typical automotvie application to illustrate. (I know that TFA - which doesn't really say ANYthing, natch - doesn't explicitly state that their "revolutionary" material is for automotive applications, but that's where all the money is coming from these days.)
What I want to do is expose the dehydrogenated powder (it's usually a powder) to hydrogen gas at about 1 atmosphere (~15 psi), remove some heat of reaction (for later use, naturally) and go on with my business. Preferably at a "hydrogen filling station", whatever that ends up looking like. Oh, and refueling shouldn't take more than about 5 minutes. And once the tank is full, I should be able to drive 300 miles without filling up again.
Right now, there is NO material known on Earth that can fulfill these requirements and still be designed into a car.
The astute reader will notice immediately that I'm leaving out what might be the single-most crucial design driver: SAFETY. I don't know if everyone's been keeping up, but alane (and the alanate hydrides in general) are ROCKET FUELS. Personally, I don't want to drive around with 20kg of solid rocket fuel in my car's gas tank. In this case, safety will absolutely drive eventual adoption, even trumping reversible storage fraction.
For example, sodium alanate (NaAlH4) has a theoretical storage fraction of 5.6%, and the reversible fraction is starting to approach 4-5%, which is a very, very good track record. However, when it sees water (which it might, in a car accident) it EXPLODES. Well, deflagrates, but you get the point.
(rant on)
Don't get me wrong. I'm all about solid-state H2 storage, and the "H2 economy" in general, whatever that happens to be. I'm even a "real" materials engineer, working with hydrides. But I'm also all about reality, and hopefully trying to "drop the veil" of proprietary information wherever possible. We're working as a team, people. So, to the press folks at UNB: write better articles, publish some papers, or both.
Well, even if something like that did happen, I have the feeling nothing much would come of it down here. Each of THEMIS's probes (there are 5) is about the size of a largish television. Not very big; in fact, plenty small enough to mostly, if not completely, burn up on re-entry.
Besides which, they're also pretty light (i.e., low-mass). THEMIS was constructed out of low-magnetic susceptability materials (which, in this case, also happen to be low-mass) so that the probes wouldn't interfere with the local magnetic field. On-board sensors get higher sensitivity that way.
*disclaimer: I used to work for the folks that helped build THEMIS, so I guess I'm not impartial. Then again, $#@! happens.
Um...I may be from California, but even I know that it's Barbara BOXER.
Thanks, and good-night.
-joe.
Re:Some things I don't get about open source
on
Netscape Reborn?
·
· Score: 1
The challenge of Open Source - and I think the immediate parent hits it here, albeit tangentially - is the subtle difference between "the greatest freedom for the most folks" and "the greatest freedom for the most folks for the right reasons".
It's ironic - and the parent clearly communicates this (but, correct me if I'm wrong) - to comment that freedom is denied to some to "...use GPL'd code in our own, closed-source projects"; such freedom can only be given by stripping it from those further "down" the common social chain, those that would arguably (in some respects) exercise it the most, and for those "right reasons."
I realize, of course, that for many this argument is probably on shaky ground. But it only looks that way.
Hello, high voltage. It's one thing to put "phased array" antennas on naval vessels, but entirely another to put them in a house. Not to mention the voltage difference needed to generate the plasma.
Fluorescent bulbs use this sort of principle, too - surely our new gas-plasma antennas aren't to be made of glass?
You know, there is a subtle issue of "ownership" raised by the parent. In the case of a DVD rented from Blockbuster or a cable box leased from the cable company, I'd have to wonder if copyright/fair use doctrines extend all the way across the "use" of these systems.
I dunno; perhaps someone knows more about Fair Use and ownership than I do. The cable box and the rented DVD are not exactly in the public domain, either.
And it's not that I wouldn't hack at either one of them - I just wonder if this is the kind of detail that presents a loophole for the minions of the DMCA.
I feel I have to say that, in light of the many comments already concerning perpetual motion (and yes, I've read the $#@!ing article), I really think that it's pretty weird that my last comment on the Second Law of Thermodynamics was moderated "Offtopic."
[/rant]
Obviously, it's absurd that anything that relies only upon a gravitational potential energy exchange can stay airborne forever, especially a vehicle that relies on a dissipative medium (i.e. air) to provide lift.
This should have been obvious from my first comment, and so I think I need to moderate my moderator as "-1, Uneducated."
Idiot Filter, indeed. So go ahead, metamoderate me this time; see if I care. But first, just promise me that you'll read the article (and go to college) first.
Slashdot Mirror
Minor footnote: author Kim Stanley Robinson wrote presciently about this technology in his Mars trilogy (specifically, "Green Mars", I believe.)
--joe.
Uhh, don't forget Genesis:
http://genesismission.jpl.nasa.gov/
Sure, it had a hairy reentry/recovery, but it certainly recovered samples from the inner Solar System. These were likely attributable to the Sun or were of interstellar origin.
--joe.
...but I can summarize my eventual response regardless:
That is NOT evolution.
--joe.
http://en.wikipedia.org/wiki/Yavin ...I mean, in the litany of famous gas-giants, this one certainly rates. Not much else could get between the rebels and the first Death Star.
Delays and ballooning expenses: some reform at NASA is in order...
Well, your comment is undoubtedly going to be a common one.
I was almost inspired to begin "Oh, please...", but I have to admit: I'm a technocrat at heart, and it's just a knee-jerk reaction.
Regarding Stern's Op-Ed, note that he was in SMD (Science Mission Directorate), a portion of NASA that routinely suffers cutbacks that reward "...the guilty" and punish "...the innocent," to borrow his phraseology, mostly in favor of the Manned Space Program.
The issue facing MSL is, indeed, endemic within the ranks of advanced "marquee" missions; furthermore, one cannot ignore the fact that it is easily the most advanced planetary surface mission conceived to date. It's likely some mismatch of management and planning has occurred.
The action to delay MSL's launch until the 2011 window, though, is a choice between following through on a bad bet vs. saving an good investment. It must be seen in light of what it represents: a decision to maximize a return on an already large investment of spent money instead of wasting it unwisely on unnecessary risk.
Just 0.02.
Cheers,
--joe.
I'd like to second Colonel Korn on this one (I've certainly never written THAT before); the concept of reusable hydrogen storage materials is not a new one. It's devilishly difficult, of course, but not new. Check out http://hydrogen.energy.gov/ to see what's been done so far.
Buckyballs, like carbon nanotubes (CNTs) before them, store hydrogen by physisorption, whereby hydrogen molecules (not atoms, usually) "stick" to the near-surface via van der Waals forces (or equivalent). The issue with CNTs, of course, is that they really didn't do it as well as folks had hoped (or originally thought; there was some controversy over this). Overall, physisorption systems (the AD- vs. AB-sorption that the parent was referring to) don't do as well as chemisorption systems like metallic hydrides, though. The peak capacities are something like 3-6% vs. 12-15%, respectively.
But let's not mince words here; the real key issue in this case is that the nice folks at Rice have RUN A MODEL. They haven't done any empirical work to determine whether this actually works. If you've been keeping score here, that's where the rubber meets the road. Personally, I'm not holding my breath on the claimed 8% number.
After working in this field for a while, I've noticed that these kinds of claims appear at regular intervals (usually from universities with good media departments) regarding "miracle materials" that store tons of hydrogen. Don't get me wrong; any active thinking is progress - but let's be productively skeptical, eh?
To Rice's PR department: good show, but I don't buy it. Sorry for the cynicism.
Cheers,
--joe.
I'd like to hope that the "geniuses" comment featured in the article post, but I honestly can't tell. I think some of the previous posts point out, better than I can, how unseemly sarcasm would be in this case.
For information on how successful the Ulysses mission has actually been, including its recent historic third pass over the north solar pole, Please refer to the Ulysses home page at JPL:
http://ulysses.jpl.nasa.gov/
In any case, I'd like, perhaps, to suggest that the article post could either have been written, or otherwise reviewed, with more editorial skill. Then again, maybe that's asking too much. And that statement was not intended to be sarcastic.
Cheers,
--joe.
I'll make the same pitch again for folks to drill down on the .gov hydrogen site; there's a lot of useful info there.
There are definitely more than one promising solid hydrogen carrier; hydride materials come in easily dozens of chemical families, about 5-10 of which are under considerable investigation.
There aren't as many options for a liquid carrier; there are (or rather, were) two general approaches if I recall correctly - one, an organic (i.e., carbon-based) carrier solution (a slurry, really) in which hydrogen would be soluble; the other, something like ammonia-borane or other N-B-H compounds, also liquid. The latter is, obviously, inorganic - but not trivial, since it might tend to release ammonia or borane products, both very bad things for fuel cells (not to mention people).
I think there's a lot of development in this area, but unfortunately I'm not terribly familiar with the chemistry, technically speaking.
Cheers,
--joe.
If you're interested in this technology area, you can definitely start by following the .gov link in my post. Much of the published data produced by groups under the DOE funding can eventually be found there; there are annual reports and other such summaries.
Some pretty hard-core (but still interesting) stuff is at this link, for example; tech publications and such:
http://www1.eere.energy.gov/hydrogenandfuelcells/hydrogen_publications.html#h2_storage
As for the idea of hydrogen dissolved in solid material, that technology area refers to "metal hydrides", which are metallic alloys and related compounds that - among other behaviors - can literally "soak up" gaseous hydrogen like a sponge. And many can do this at room temperature, at or under atmospheric pressure (read: relatively inert/safe).
You know nickel-metal-hydride (NiMH) batteries? Although this rechargeable technology is on the way out as Li-ion batteries mature, they contain exactly these kinds of materials. Metal hydride technology isn't so new, actually; the chemical effect has been known for, I don't know; something like 75 years or so. As a useful technology, though, it was the arms race (i.e., nuclear weapon research) that pushed the envelope in the 50s and 60s.
Hope that helps. As for "odorizing" the hydrogen, it's probably more preferable to employ sensitive detectors that will warn folks of an H2 leak long before their noses can. Never can tell, though.
Cheers,
--joe.
Another Hindenburg reference. Great fricking Caesar's Ghost.
Seriously, though - and on a tangent for a sec - he's got a point. No, not about a hydrogen-fueled car ACTUALLY bursting into flames a'la the great Lakehurst weenie roast (that's why he used a smiley-face, I guess) but - unwittingly - about the public's perception of the implications of having hydrogen on-board a road vehicle.
The truth is, technology wants to go in a safer direction. The US DOE is spending a lot of money - well-spent, in my opinion - on developing components of an automotive approach to hydrogen fuels, including infrastructure, end-to-end efficiency and cost, and of course materials science and engineering.
Check out http://hydrogen.energy.gov/
The long and the short of it is this: the current standard is to store compressed hydrogen on-board in 5000 psig tanks; the tech maturation for this approach is to up the ante to 10000 psig. Yikes; no wonder the public has the wrong idea - that's a lot of mechanical energy stored up in there. Some of the more interesting (but not new) technology DOE is funding is for "absorptive" storage, both liquid- and solid-state, wherein the hydrogen isn't at high levels of compression - rather, it's safely (for the most part) tucked away inside the molecular structure of a parent "carrier" substance. At fairly low pressures (~15-150 psig), for the most part.
Okay, tangent over. In the interest of full disclosure, I am a hydrogen materials engineer. And I'm WAY more frightened of gasoline vapors than I am of hydrogen in any form.
Cheers,
--joe.
Cheers - I thought I was the ONLY person who read all those books. Trying to explain them to most folks is a losing proposition; thanks goodness for Wikipedia. Poor Danny and his friends never had the clout of, say, the Hardy Boys.
But as far as I'm concerned, Irene Miller could beat the $#@! out of Nancy Drew.
--joe.
You realize, of course, that my portrayal of Mr. Clarke's message said nothing about the monolith or his choice of Iapetus as its location. I was merely referring to the fact that, as is evidenced by the text of "2001", his physical description of Iapetus is eerily accurate for the time, all things considered. Believe me, that fact has given rise to more than one website's claim of conspiracy...
As for the perceived transitive nature of the verb "reminded"...actually, that's not how I meant it at all. I suppose I intended more to imply that the audience was reminded by inference, but in my excitement probably failed to make that clear. My bad.
I'm also with the poster that suggests that Clarke is due a little ego-stroking now and then...
Cheers,
--joe.
Technically, the Mars Sample Return http://mars.jpl.nasa.gov/technology/samplereturn/i ndex.html is a precursor mission (i.e., before manned landings) that's been "on the books", so to speak, for a while. It's a developmental mission model, having been bounced back-and-forth between front and back burners for a while, now, but the technology is all there. It's very expensive, as you can imagine, so that's part of the reason why it's not "ready" yet. Other reasons have to do with local infrastructure - we'd like to have a handle on good surface communications on Mars - and the fact that the science community can't really decide on a reasonable surface target. That's being helped by MER, and will really get a
good kick in the pants by the Mars Science Laboratory (MSL), which will be launching in 2009.
Of course, the public have very varied opinions about this...for example,when you Google "Mars Sample Return" you still get http://www.icamsr.org/ as your first hit. Sheesh.
Uphill battle, maybe.
--joe.
Actually, there's some body of work that describes a larger problem for Lunar explorers, although the Martian problem isn't anything to sneeze at, either. Pun intended.
As TFA points out, the lack of weathering processes on Luna leaves the dust/regolith mainly as sharp-edged grains, which actually gives them incredible abrasive power. This poses an enormous problem for mechanical assemblies that have any wear surfaces. The Apollo astronauts, IIRC, went through a couple pairs of suit gloves each simply from the wear of the dust on their metallic glove locking rings.
Martian dust might have a similar range of effects, but I hadn't heard of the "toxic dust" issue, yet; that's the interesting bit. Silicosis of the lungs and related disorders, yes; toxicity, no. Yikes.
Toxic dust makes me think of the blended iPhone. "Don't breathe this." Sorry, that's another article...
-joe.
Absolutely true - I was going to mention the bond energy of water (460 kJ/mol, if anyone cares - or is still reading this). Other than that, yes, the hydrogen storage density of water is quite high. Trouble is, the instant you remove a single hydrogen atom, you get hydroxide, which generally doesn't do nice things to fluid systems. The trick is removing both H atoms. It gets easier for the second one, which is nice.
However (and I don't remember exactly how), there are catalysis effects that promote water dissociation without high temperatures, for example, or other non-ideal processing steps. Gotta achieve the bond energy, though; that's still thermodynamics. But platinum, palladium, and others can be used (I think) to selectively sweep the hydrogen from the feedstock. You can do "photo-dissociation" too, IIRC.
While we're on the subject, how about some passive solar power, doing nothing but cracking water 24/7? I mean, we're going to have to get all this hydrogen from someplace...yeah, I know - takes a LOT of panel area.
-joe.
I agree that it would appear they could be talking about Alane (AlH3), which has a theoretical weight-density of about 10% hydrogen. Yes, 10% is good...but as folks in the hydrogen storage community would be quick to tell you, it's not unusual. For example, Lithium Borohydride (LiBH4) has a theoretical weight-density of almost 18.5% hydrogen! The key is simply to bind hydrogen with light elements in a stable configuration, right?
Wrong. That's not even the tip of the iceberg.
The real problem, as any hydride person would correctly point out, is not "theoretical storage fraction"; rather, it's REVERSIBLE storage fraction. It doesn't really matter, in the long run, if you can store 18%, or even 25% hydrogen by weight in a substance if the following are true:
1. it takes a LOT of energy to put it in (theormodynamically unfavorable hydrogenation reaction)
2. you can only get out a small fraction of what you put in under favorable conditions (non-reversibility)
3. the reaction doesn't move very quickly (unfavorable kinetics)
With these limitations, you face a severe energy penalty for trying to use the material as a hydrogen carrier, mostly because it's one-way. The keys to an inexpensive, efficient solid-state hydrogen storage material combine high storage fraction with a high level of reversibility: why bother using a material if you have to ship it back to the "refinery" when the hydrogen has been depleted? As an example, let me use the typical automotvie application to illustrate. (I know that TFA - which doesn't really say ANYthing, natch - doesn't explicitly state that their "revolutionary" material is for automotive applications, but that's where all the money is coming from these days.)
What I want to do is expose the dehydrogenated powder (it's usually a powder) to hydrogen gas at about 1 atmosphere (~15 psi), remove some heat of reaction (for later use, naturally) and go on with my business. Preferably at a "hydrogen filling station", whatever that ends up looking like. Oh, and refueling shouldn't take more than about 5 minutes. And once the tank is full, I should be able to drive 300 miles without filling up again.
Right now, there is NO material known on Earth that can fulfill these requirements and still be designed into a car.
The astute reader will notice immediately that I'm leaving out what might be the single-most crucial design driver: SAFETY. I don't know if everyone's been keeping up, but alane (and the alanate hydrides in general) are ROCKET FUELS. Personally, I don't want to drive around with 20kg of solid rocket fuel in my car's gas tank. In this case, safety will absolutely drive eventual adoption, even trumping reversible storage fraction.
For example, sodium alanate (NaAlH4) has a theoretical storage fraction of 5.6%, and the reversible fraction is starting to approach 4-5%, which is a very, very good track record. However, when it sees water (which it might, in a car accident) it EXPLODES. Well, deflagrates, but you get the point.
(rant on)
Don't get me wrong. I'm all about solid-state H2 storage, and the "H2 economy" in general, whatever that happens to be. I'm even a "real" materials engineer, working with hydrides. But I'm also all about reality, and hopefully trying to "drop the veil" of proprietary information wherever possible. We're working as a team, people. So, to the press folks at UNB: write better articles, publish some papers, or both.
(rant off)
-joe.
Well, even if something like that did happen, I have the feeling nothing much would come of it down here. Each of THEMIS's probes (there are 5) is about the size of a largish television. Not very big; in fact, plenty small enough to mostly, if not completely, burn up on re-entry.
Besides which, they're also pretty light (i.e., low-mass). THEMIS was constructed out of low-magnetic susceptability materials (which, in this case, also happen to be low-mass) so that the probes wouldn't interfere with the local magnetic field. On-board sensors get higher sensitivity that way.
*disclaimer: I used to work for the folks that helped build THEMIS, so I guess I'm not impartial. Then again, $#@! happens.
-joe.
I don't mean to be snippy, but how can the parent be redundant if it was posted first?
Just wondering.
-joe.
Um...I may be from California, but even I know that it's Barbara BOXER.
Thanks, and good-night.
-joe.
It's ironic - and the parent clearly communicates this (but, correct me if I'm wrong) - to comment that freedom is denied to some to "...use GPL'd code in our own, closed-source projects"; such freedom can only be given by stripping it from those further "down" the common social chain, those that would arguably (in some respects) exercise it the most, and for those "right reasons."
I realize, of course, that for many this argument is probably on shaky ground. But it only looks that way.
-joe.
I think Marty McFly already wore these sneakers in BTTF2. You know, the ones that had the automatic-inflation feature. Of course, they were Nikes.
This definitely tears it; Robert Zemeckis was a $#@!ing genius visionary. can't wait for the "Mr. Fusion."
-joe.
Hello, high voltage. It's one thing to put "phased array" antennas on naval vessels, but entirely another to put them in a house. Not to mention the voltage difference needed to generate the plasma.
Fluorescent bulbs use this sort of principle, too - surely our new gas-plasma antennas aren't to be made of glass?
Hrm. Perhaps they are.
You know, there is a subtle issue of "ownership" raised by the parent. In the case of a DVD rented from Blockbuster or a cable box leased from the cable company, I'd have to wonder if copyright/fair use doctrines extend all the way across the "use" of these systems.
I dunno; perhaps someone knows more about Fair Use and ownership than I do. The cable box and the rented DVD are not exactly in the public domain, either.
And it's not that I wouldn't hack at either one of them - I just wonder if this is the kind of detail that presents a loophole for the minions of the DMCA.
-joe.
[rant]
I feel I have to say that, in light of the many comments already concerning perpetual motion (and yes, I've read the $#@!ing article), I really think that it's pretty weird that my last comment on the Second Law of Thermodynamics was moderated "Offtopic."
[/rant]
Obviously, it's absurd that anything that relies only upon a gravitational potential energy exchange can stay airborne forever, especially a vehicle that relies on a dissipative medium (i.e. air) to provide lift.
This should have been obvious from my first comment, and so I think I need to moderate my moderator as "-1, Uneducated."
Idiot Filter, indeed. So go ahead, metamoderate me this time; see if I care. But first, just promise me that you'll read the article (and go to college) first.
-joe.
Apparently, these people have never heard of the Second Law of Thermodynamics...or, in layperson's terms, "The Idiot Filter."
-joe.