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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."
...perfect for espresso machines.
Is it just me or water can't be very very hot? At about 100 degrees Celcius, it vaporize...
Yes it does at standard temperature and pressure. If you were to increase the pressure it would require a higher temperature to vaporize, just as lower pressures require lower temperatures.
Water can be superheated as much as you please, it simply has to be at a high enough pressure. Past water's critical point (about 650 K and 22 MPa), it becomes a supercritical vapor, indistinguishable from liquid or vapor. Additionally, the boundary between liquid and gas dissapears, and the properties of the substance are somewhat different.
Simple: Cost.
You'd have to build something on the same scale as the current oil pipeline system, but with the added hurdle of being able to hold hydrogen.
The current system won't work since it can't hold hydrogen.
Also with no immediate profit, people tend not to like investing is something they won't see return on in the short term.
Already invented:
Mini nuclear reactor could power apartment blocks
A nuclear reactor designed to generate power in the basement of an apartment block is being developed in Japan
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.
Does that mean they will be showing their privates in public? Are there any females on this public-private team? If so, then I am there for the 'unveiling'!
I had so many unwanted daemons on my machine, I had to hire a priest to cast them all out.
I thought of this when someone first told me about fuel cells. To anyone familiar with conventional thermal cycles and the basics of thermodynamics, the approach is obvious. Thermal cycles take advantage of thermal energy gradients. That such a potential could be exploited with fuel cells seems to be an obvious extention. Hot water is easier to separate than cold water, duh! So you heat the water up, separate it and then combine it in a cold fuel cell. The difference is energy you can use but the devil is in the details. It seems easier than using a turbine but you'd want one of those too if you can't extract all of the heat in electrolysis.
I'm glad someone is finally working on it. People are so slow. I expect the petroleum and coal industries to step in and kill it before anyone can use it.
Friends don't help friends install M$ junk.
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.
A preposition is a terrible thing to end a sentence with.
Generation IV Nuclear Reactors
Very high-temperature gas reactors. These are graphite-moderated, helium-cooled reactors, based on substantial experience . The core can be built of prismatic blocks such as the Japanese HTTR and the GTMHR under development by General Atomics and others in Russia, or it may be pebble bed such as the Chinese HTR-10 and the PBMR under development in South Africa, with international partners. Outlet temperature of 1000C enables thermochemical hydrogen production via an intermediate heat exchanger, with electricity cogeneration, or direct high-efficiency driving of a gas turbine (Brayton cycle). There is some flexibility in fuels, but no recycle. Modules of 600 MW thermal are envisaged
This isn't really correct - although pretty much all the power reactors in the USA are water cooled (primarily due to the Navy's interest is nuclear propulsion), there are plenty of gas cooled reactors elsewhere. Most of our (Britain's) nuclear generating capacity is from either AGR (Advanced Gas-cooled Reactors) or Magnox (named after the Mg-alloy fuel can) reactors, both of which use carbon dioxide as the coolant.
So, the technology may be new to the USA, but there's are wealth of knowledge on designing and running these reactors elsewhere in the world.
Oh yes, they're arguably quite a bit safer than PWRs as well!
Yes, as we all know, deuterium is somewhere down there in the middle of the periodic table, it must be one of those weird elements you don't hear about much. What was its elemental symbol again? Du?
p.s. Don't drink your tap water! Check the news, it's been contaminated with dihydrogen monoxide, which at sufficiently large quantities can prevent breathing!
There were interstate oil pipelines completed or under construction before World War II. U-Boat attacks on coastal tankers accelerated the process. Today, there are 200,000 miles of oil pipelines and 2/3 of US oil is transported by pipeline. Houston to New York, the cost is about $1 a barrel, or 2 1/2 cents a gallon at retail. Association of Oil Pipelines
I don't think it's that hard actually.
While I can't verify the temperature that the water was at, I had an incident this weekend that indicates this super-heating is not too difficult.
I put a 2 cup pyrex measuring cup in a microwave for about 2.5 minutes. The water appeared very calm and didn't have any bubbles. But as soon as I dropped my tea-bag into the cup, the water flared up and began to boil very vigorously for a few seconds.
The water was filtered drinking water from Walmart, and the pyrex was only cleaned with tap-water (rather "hard" water) and soap.
polar h20 molecules are flipped or spun as the microwave passes by them. because the em field emparts energy into the molecules, they can contain enough energy to phase shift. Think about covering a gym floor with basket balls so that none are touching. Then somehow make every ball spin at 10000 rpm. At first the balls would continue to sit on the floor spinning really fast. They have a ton of energy, but are still floor balls. Then a single ball is nudged into it's neighbor. Suddenly a chain reaction would happen with basketballs flying everywhere as the spin energy is converted into movement energy.
same thing happens in a microwave to h20, or any other free floating polar molecule. h20 just happen to absorb the microwave em very efficiently.