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Creating Hydrogen With (Very) Hot Water
carbonman writes "NYTimes is reporting that a public-private research team will announce on Monday that they have discovered a new technique to produce pure hydrogen that is far more efficient than conventional methods. The advance could be a significant development in attempts to realize the dream of the hydrogen economy in taking gasoline-powered vehicles off the road, and without releasing carbon dioxide emissions that are linked to climate change. It does, however, require the use of advanced high-temperature nuclear reactors, none of which have been built on a production scale before."
swiftstream adds a link to the same story at the no-reg Indianapolis Star, and summarizes the method as "electrolysis of very, very hot water."
I think the reality is that there are so many unecissary regulations in the states, that nuclear power is impossible - and likely will be for a long time. I myself wish I had enough money to buy a ship and put a nuclear reactor on it out in international waters and sell safe and simple hydrogen back to the mainland. It would also be a cool way to reach the next generation of liberty - I mean we haven't really seen any new methods implemented to improve individual freedom and liberty (especially economic) in government in nearly 200 years. I wish I could start a nation at sea.
When the current Danish natural gas pipeline network (the one that connects cities and houses) was designed, one of the requirements was that the network could carry hydrogen instead of natural gas.
If they drilled deep enough into the Earth's crust, they could do away with the nuclear reactor bit altogether, and use the natural heat of the planet.
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Hmm, nuclear reactions? Isn't the point to get hydrogen to be used with fusion(w/ helium3) without any byproducts? If you need to start using nuclear reactions, this still isn't a 'great' way to get hydrogen. I still believe using solarpanels and using electrolysis for getting hydrogen is still the best way. No CO2, no nuclear waste... Well that's just my opinion...
Fusion of helium-3 would be divine. Pity there isn't much here on Earth. (The moon is another matter.) It also usually costs hundred of dollars per litre. Bear in mind that there are several other reaction paths to fusion that don't require He-3. They aren't as ideal - just more practical.
Solar panels have their place, but they're never going to produce the amount of hydrogen needed for even a single nation's infrastructure. Even if solar panels were much more efficient, electrolysis itself isn't very energy efficient.
(As an aside, I was pleasantly suprised to run across an article about using good old Stirling engines & an array of mirrors to generate power from the sun - at higer efficiencies than panels and at costs comparable to fossil fuels. Have a read)
Now, on to the point of the story. Basically, some of the Generation IV nuclear reactor designs* can be used to produce lots of hydrogen, more or less as a byproduct of their operation. (Because of the extreme temperatures) So the fact that you've suddenly got the means for a hydrogen economy is a side-benefit.
Gen. IV reactor designs are cleaner, safer, more efficient, and generally smaller than their clunky old (current) counterparts. Yes, they are still fission. And while MOX reactors (which compose some of the designs) have questions about fuel reuse, a bona fide fusion reactor can be used to re-enrich spent fission fuel. (ie, blanket of uranium around reaction chamber, etc.) Fusion lets you make fission clean, or as close to it as possible.
Why is that important? Because no one is going to initially drop the trillion or so dollars to build the first commercially viable fusion reactor, when and if one is ever designed. ITER itself will be just a stepping stone, if it ever actually gets built. In the mean time, we'll still be fissioning away...
*Because of irrational fear and paranoia in the USA, most commercial reactors are Generation I or II. Not much has changed since the 70s. Nuclear can be dangerous, but it generally isn't and needn't be. It's debatable whether government run power plants would be any better, but it scares the hell out of me that our reactors in the USA are run as cheaply as they can possibly get away with. Capitalism is great, but you just can't try to undercut safety.
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Is it possible to take this naturally superheated water and use it to create hydrogen more efficently?
True, but water vapour condenses out of the atmosphere as precipitation. There are hyrdological and carbon cycles that dictate equilibrium for greenhouse gases.
We actually wouldn't have a problem with carbon dioxide emissions if they were a part of the carbon cycle. Biodiesle would not contribute to the greenhouse effect, since the amount of CO2 released and the amount absorbed by the plants producing the fuel would be in equilibrium. However by burning trapped fossil material, which has been out of the carbon cycle and buried for millions of years, we are altering the environment.
Carbon dioxide is normal in the air; animals emit it, plants consume it. Add more total carbon to the system, by depleting an ancient carbon sink, and the net level of CO2 in the air rises. Since the hydrogen you get from electrolysis comes from water, you aren't adding to the net levels of water vapour. For every ounce of water you're releasing into the hydrological cylce, you're taking an ounce out at the other end to get the hydrogen in the first place. No disruption in the hydrological cycle, no warming.
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At the levels of CO2 that we're putting into the atmosphere today, it's likely that biological sinks could reduce CO2 to preindustrial levels in about 200 years, but if we continue to burn fossil fuels for the next two centuries, the biological and short-term chemical sinks will have been saturated.
Based on what we know about the slow (geological) sinks, it could well take on the order of a few million years to get back to preindustrial levels of CO2 from the levels we expect if we burn up all the known coal reserves (estimated at around 250 years from now at current rates of consumption).
Therefore, I am much more concerned with CO2 emissions than with nuclear waste.
You can perform the same trick the other direction. If you carefully cool a cup of water using the right container, you can get it a fair amount below 0C at normal pressure. Throw in a grain of salt, and the whole thing violently freezes, sometimes shattering the container.
Phase changes just require some sort of trigger, often a tiny bit of turbulent flow around a sharp corner, scratch, or any local disturbance. The further the fluid is above or below its expected boiling or freezing point, the more unstable the situation is and the smaller the trigger needed.
With standard household stuff, superheating or supercooling water by 5C-10C is doable. The shattered glass trick is tougher because you need to supercool water about 15C-20C to get sufficiently violent freezing. When the fridge compressor is running, it usually generates enough vibration to trigger the phase change before the water is cold enough.
Here's a nice Sandia link that makes it absolutely clear that even a small-scale solar thermal installation can produce temperatures comparable to those in "nuclear explosions" the article here is only talking about 2000C. This solar furnace is used to test the "failure thresholds of high temperature ceramic and refractory materials." So why in the hell is a nuclear power plant the only option to produce the heat they need to use with their fancy ceramic filter? No doubt the solar furnace in that photo produces temperatures far in excess of what their ceramic filter can even tolerate.