[alexander]

Even though this belongs in technology section more, i figured that more people will see it here... anyways i figured that not everyone has a subscribtion to NY Times and that not everyone here checks their webpage day to day, so here is a very interesting article:
"Nov. 27 - Researchers at a government nuclear laboratory and a ceramics company in Salt Lake City say they have found a way to produce pure hydrogen with far less energy than other methods, raising the possibility of using nuclear power to indirectly wean the transportation system from its dependence on oil.

"
The development would move the country closer to the Energy Department's goal of a "hydrogen economy," in which hydrogen would be created through a variety of means, and would be consumed by devices called fuel cells, to make electricity to run cars and for other purposes. Experts cite three big roadblocks to a hydrogen economy: manufacturing hydrogen cleanly and at low cost, finding a way to ship it and store it on the vehicles that use it, and reducing the astronomical price of fuel cells.

"This is a breakthrough in the first part," said J. Stephen Herring, a consulting engineer at the Idaho National Engineering and Environmental Laboratory, which plans to announce the development on Monday with Cerametec Inc. of Salt Lake City.

The developers also said the hydrogen could be used by oil companies to stretch oil supplies even without solving the fuel cell and transportation problems.

Mr. Herring said the experimental work showed the "highest-known production rate of hydrogen by high-temperature electrolysis."

But the plan requires the building of a new kind of nuclear reactor, at a time when the United States is not even building conventional reactors. And the cost estimates are uncertain.

The heart of the plan is an improvement on the most convenient way to make hydrogen, which is to run electric current through water, splitting the H2O molecule into hydrogen and oxygen. This process, called electrolysis, now has a drawback: if the electricity comes from coal, which is the biggest source of power in this country, then the energy value of the ingredients - the amount of energy given off when the fuel is burned - is three and a half to four times larger than the energy value of the product. Also, carbon dioxide and nitrogen oxide emissions increase when the additional coal is burned.

Hydrogen can also be made by mixing steam with natural gas and breaking apart both molecules, but the price of natural gas is rising rapidly.

The new method involves running electricity through water that has a very high temperature. As the water molecule breaks up, a ceramic sieve separates the oxygen from the hydrogen. The resulting hydrogen has about half the energy value of the energy put into the process, the developers say. Such losses may be acceptable, or even desirable, because hydrogen for a nuclear reactor can be substituted for oil, which is imported and expensive, and because the basic fuel, uranium, is plentiful.

The idea is to build a reactor that would heat the cooling medium in the nuclear core, in this case helium gas, to about 1,000 degrees Celsius, or more than 1,800 degrees Fahrenheit. The existing generation of reactors, used exclusively for electric generation, use water for cooling and heat it to only about 300 degrees Celsius.

The hot gas would be used two ways. It would spin a turbine to make electricity, which could be run through the water being separated. And it would heat that water, to 800 degrees Celsius. But if electricity demand on the power grid ran extremely high, the hydrogen production could easily be shut down for a few hours, and all of the energy could be converted to electricity, designers say.

The goal is to create a reactor that could produce about 300 megawatts of electricity for the grid, enough to run about 300,000 window air-conditioners, or produce about 2.5 kilos of hydrogen per second. When burned, a kilo of hydrogen has about the same energy value as a gallon of unleaded regular gasoline. But fuel cells, which work without burning, get about twice as much work out of each unit of fuel. So if used in automotive fuel cells, the reactor might replace more than 400,000 gallons of gasoline per day.

The part of the plan that the laboratory and the ceramics company have tested is high-temperature electrolysis. There is only limited experience building high-temperature gas-cooled reactors, though, and no one in this country has ordered any kind of big reactor, even those of more conventional design, in 30 years, except for those whose construction was canceled before completion.

Another problem is that the United States has no infrastructure for shipping large volumes of hydrogen. Currently, most hydrogen is produced at the point where it is used, mostly in oil refineries. Hydrogen is used to draw the sulfur out of crude oil, and to break up hydrocarbon molecules that are too big for use in liquid fuel, and change the carbon-hydrogen ratio to one more favorable for vehicle fuel.

Mr. Herring suggested another use, however: recovering usable fuel from the Athabasca Tar Sands in Alberta, Canada. The reserves there may hold the largest oil deposits in the world, but extracting them and converting them into a gasoline substitute requires copious amounts of steam and hydrogen, both products of the reactor."

[CraigD]

As a scienceforums.com newbie, I’m not sure if replying to old threads is sensible, but as a H head since the 1970s, can’t resist a H fuel discussion.

I’ve doubts about the feasibility a hydrogen-based energy distribution system that’s patterned too nearly after the prevailing oil-based system. If it’s to be successful, I believe that hydrogen will need to be produced at the point of sale – the pump – rather than at large (possibly nuclear fission) facilities, then transported to the point of sale.

Because hydrogen, a tiny molecule that tends to leak past or through most containers, is practically the most difficult substance existent to handle the way we’re accustom to handling oil-based fuel.

Most current demonstration hydrogen fuel cell-powered vehicles create hydrogen and store relatively small amounts of hydrogen at the point of sale, using water and electricity supplied by ordinary water and power distribution systems. As alexander’s starting post cites, this is prohibitively inefficient for widespread implementation.

I’ve a lot of hope that hydrogen can be efficiently generated using next-generation regenerative fuel cells. A good discussion of these can be read at the first-googled http://www.llnl.gov/str/Mitlit.html . Currently, RFCs are small – around 50 Watts (an unspectacular passenger car needs about 50,000 W peak power), and “unitized” – that is, able only to create and store hydrogen for their own use, not for extraction, so “next generation” means not only more powerful, but fundamentally redesigned – “de-unitized”. Nonetheless, I think they’re feasible.

[UncleAl]

But the plan requires the building of a new kind of nuclear reactor.
And it would heat that water to 800 degrees Celsius

.

Quartz is hydrothermally grown at 300-400 C and 23,000 psi tops. The autoclave wall is a foot thick. The autoclave is loaded, sealed, warmed, and convection does the rest - no feedthroughs. Growing quartz has been refined over more than 50 years. The heavily armored autoclaves are ungodly expensive and still occasionally explode.

http://www.ndt.net/article/apcndt01/.../1160/1160.htm
Nasty boom boom problems even with tiny lab high pressure autoclaves.

You want to run 400+ C higher in temp, with feedthroughs and insulation for high amperage electricity and hydrogen handling at 800C? Look up hydrogen embrittlement.

http://www.lsbu.ac.uk/water/phase.html
Note temp in K not C!

Are you insane? The pressure could be no less than 10^11 Pa or 15 million psi. Yer gonna generate and handle thousands of metric tonnes of hydrogen at 15 million psi and 800 C? HA HA HA!!! Liquid water at 800 C eats everything. Nothing could contain the hydrogen. It would diffuse through solid steel. Steel at 800 C deforms under modest pressure. Nickel superalloys might survive it. Go price 1000 metric tonnes of fabricated Hastelloy C-2000. Does your calculator go that high?

How are you going to run insulated electrodes through the containment wall? Do you think a compression fitting or a cone fitting will hold at 15 million psi? What will you use as the electrical insulator? No organic survives even 400 C continuous. Ceramics under those conditions in water plus electolyte (Gonna use acid? Base? What salt whose anions will not preferentially undergo redox?) rapidly dissolve. But wait! There's more! What makes you think COPPER will stick around chemically or physically? It will flow like, well, water when 15 million psi is doing the pushing.

How do you plant to pump in more water at 15 million psi and 800 C as it is progressively consumed by electrolysis? Where will the oxygen go? Do you imagine pure oxygen will be corrosive to metal at 15 million psi and 800 C (bright red heat)?

The nuclear reactor specs are also doubtful, but why worry about that? /_\(PV) is energy, 101.325 J/liter-atm. Your electrolysis reactor would loose the energy of a mini-nuke if it breached.

[alexander]

aah, well it took a little while to get any kind of response thanks for both of your contributions, I'll try to answer your questions as best i can, obviously the details of the project (hydrogen recovery IGCC syngas)

Originally Posted by UncleAl

Are you insane? The pressure could be no less than 10^11 Pa or 15 million psi. Yer gonna generate and handle thousands of metric tonnes of hydrogen at 15 million psi and 800 C? HA HA HA!!!

afraid not quite so, hydrogen recovery from integrated gassification combined cycle systems using mixed protonic/electronic conductive membranes will provide

Originally Posted by ceramatec.com

high-pressure H2-rich gas (50-100 psi)

and to tell ya the truth i dont have any idea where you got your 15 million psi to start with... (perhaps long hard math equations, could you specify?)

It would diffuse through solid steel.

ceramics can be much stronger and more durable then steel, and since INEEL is teaming up with Ceramatec Inc. (company that develops and pattents ceramic types) I'd imagine that the containers would be ceramic, and not steel.

Does your calculator go that high?

I didnt attack you, take it easy, or is flaming the newest fad that i've missed, i merely posted a news article, its not like i invented the hydrogen recovery IGCC syngas (otherwise this post would have been a few more pages long with detailed explanations, and complicated math and things). As to my calculator, bc, does a few hundred thousand place calculations, so I'm all set...

Originally Posted by CraigD

Because hydrogen, a tiny molecule that tends to leak past or through most containers

actually, that was and still is a huge issue, well, aside from the fact that US gov-t doesnt want anymore nuclear reactors that is...
Ceramatec actually thought of this, here's some info: http://www.ceramatec.com/techareas/techa_controlled.php

[UncleAl]

afraid not quite so, hydrogen recovery from integrated gassification combined cycle systems using mixed protonic/electronic conductive membranes will provide

This is a PHASE DIAGRAM,

http://www.lsbu.ac.uk/water/phase.html
Note temp in K not C!

This is the way the universe operates. It cannot be avoided, cheated, unseated by majority vote, or altered by shaking dust off Tinkerbell's bottom. If you want electrolysis in a "liquid-like density" phase for water at 800C (1073 K) it will have a pressure hard by 10^11 pascals or 15 million psi. It's ******** as an industrial process.

The highest commercially sustainable pressures at temperature are a factor of ten less - in HPHT diamond synthesis presses.

http://www.me.berkeley.edu/diamond/s...ro/cphased.htm

The maximum pressurized volume so obtainable is a few cubic inches. A company running HPHT presses would collapse in laughter if you suggested running feedthroughs or so pressurizing even a cubic foot.

When an HPHT press fails the spurt comes out at hypersonic speeds. Ballistic shielding will only stop the chunks flying behind it. Some large arrays of HPHT presses (Ireland) dispense with ballistic encasement entirely, given the observation that it won't make much difference, it takes up room that could be more presses, replacement labor is cheap to train, and modern presses don't rupture. Often.

[CraigD]

Engineering details aside, my doubts about the feasibility of most schemes to widely use H as a fuel go beyond favoring low temperature/pressure production methods over high.

I’m more concerned that the most popular technology for the consumer-end – proton exchange membrane fuel cells – can’t, based on reasonable assumptions, be more widely used, at anything approaching an acceptable cost. Since a material required for their manufacturing – platinum - is actually scarce, an increase in manufacturing volume would likely increase, not decrease, their cost. The next most popular technology, alkaline fuel cells, avoids prohibitive manufacturing costs, but require prohibitively expensive H and O purity.

There is, of course, an obvious and well developed method of getting work from ordinary, low-purity H and O – combustion. While inelegant compared to fuel cells, and, while very clean compared to other combustibles, not zero-emission (most of the exhaust is H2O, but unless the supplied H and O is uncontaminated, combustion byproducts similar to gasoline combustion are produced), burning H is immediately feasible. Distributed H can be used both for combustion, and in fuel cells, so combustion doesn’t negatively effect the use and advancement of fuel cells, only fills in the large nitch where they’re not economically viable.

I’m nearly at a loss to explain why H combustion has, since the late 1970s, practically disappeared from popular literature. It’s as if the major proponents of H – Ford and GM, for example – want to fail due to economic infeasibility.

IMHO, proponents of a shift from oil to H should steer clear not only of centralized H production (including nuclear), but of fuel cell consumption. Low cost should be the order of the day, avoidance of expensive materials the mantra. My modest proposal is:
1) Generate electricity via solar thermal means (example: http://www.enviromission.com.au/index1.htm )
2) Generate H at the point of dispense with reverse alkaline fuel cells (no example exists to my knowledge, but similar to http://www.ovonic.com/PDFs/fuel_cell...04_toronto.pdf )
3) Consume the generated H by combustion. (a hobbyist can do this)

[UncleAl]

The densest containment of hydrogen, atoms/liter - by a full factor of two over the most wildly extrapolated future technology - is an open bucket of diesel fuel (and you get to burn the carbon, too). It works in existing perfected IC engines. Worldwide and local distribution infrastructure is already in place and debugged.

Civilization knows what it is doing. Enviro-whiners are corrupt liars.

[nkt]

So why bother with the Hydrogen at all?

It costs a fortune to make the gear, it costs lots to split the ash (water) back into fuel, and you lose at every single stage, even in a perfect theory driven cycle.

Just drop hydrogen, and go for electric, which at least only has one crappy Carnot limited step when it is made, and 90%+ efficiency when used.

[Boerseun]

Originally Posted by nkt

So why bother with the Hydrogen at all?

It costs a fortune to make the gear, it costs lots to split the ash (water) back into fuel, and you lose at every single stage, even in a perfect theory driven cycle.

Just drop hydrogen, and go for electric, which at least only has one crappy Carnot limited step when it is made, and 90%+ efficiency when used.

...so you wanna go for 'lectric powa? Where's the 'lectricity gonna come from?

[alexander]

he probably implies wind, solar and geothermic reactors. there is a project that is designed to make solar cells work very, very well by using mirrors to direct the light to a special, and pretty small cell in the middle. I saw it on tv, and they were talking about some impressive numbers there...