Questions about a Hydrogen Economy; Scientific American

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The discussion centers on the concept of a "hydrogen economy," highlighting the misconception that hydrogen serves as a direct energy source like fossil fuels. Participants emphasize that hydrogen production requires more energy than it yields, often relying on fossil fuels or coal, which raises environmental concerns. The potential for nuclear energy to contribute to cleaner hydrogen production is noted as a preferable alternative. There is a consensus that while hydrogen can be an energy carrier, significant advancements in production technology and infrastructure are necessary for it to be a viable solution. Overall, the dialogue reflects skepticism about the feasibility of transitioning to a hydrogen economy without addressing underlying energy production challenges.
  • #271
Hah! A nuclear fan. :biggrin:
What convinces you that we can operate nuclear plants safely. That is to say, what new nuclear energy technologies make this a viable approach?
 
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  • #272
Chronos said:
Viable alternatives to hydrocarbon energy sources are well inside the radar screen.
Features vs. benefits. What was questioned was not the existence of alternatives to hydrocarbons. What was questioned was the benefit of switching.
 
  • #273
Ivan Seeking said:
Have you seen the T-Zero?
The T-Zero runs on chemical energy cell batteries, not on fuel cells. Are you talking about race cars running on batteries or fuel cells? Do you know what specific energy and specific power are? Do you know how much energy is in a typical gallon of gasoline? Do you know what the efficiency of conversion of fuel cells currently is and what it is expected to eventually be?
 
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  • #274
I repeated the quote about electric cars. I never said anything about fuel cells.

Edit: oh yes, yes, yes, and yes. Get a grip.
 
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  • #275
The motorcycle you linked to runs on a fuel cell. Do you think on-road electric vehicles might run better on batteries, fuel cells or something else? What might electric race cars run better on?
 
  • #276
Ivan Seeking said:
Hah! A nuclear fan. :biggrin:
What convinces you that we can operate nuclear plants safely. That is to say, what new nuclear energy technologies make this a viable approach?
Elementary, my dear Ivan. I've been instrumental in building 3 of them. They have all been operational for at least 20 years and not a single one has suffered a melt down - and I've also been nominated for village idiot for the 5th straight year. It's not a large village, but a village nonetheless. :smile:

Check out these designs. They are pretty impressive:

https://www.pbmr.com/
http://gt-mhr.ga.com/
 
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  • #277
Do these use ceramic coated Pu pellets?

Enlighten us about melt-down proof technologies. A friend of mine was working on this but he is now retired, leaving me out of the loop. Also, can you tell us anything about fast-flux reactor technologies?
 
  • #278
Ivan Seeking said:
Do these use ceramic coated Pu pellets?
They use graphite pellets, each containing a tiny flake of uranium. PBMRs are illegal to implement in the United States because they are so dangerous (the graphite can burn and the reactor is intended to be built without a containment, meaning that each of the thousands of mass-produced pellets needs to have its integrity assured to the same degree that single containments need to have their integrity assured today). Other countries are interested in them though.
 
  • #279
The ceramic approach seemed promising. In principle the separation between the Pu beads [pellet cores] assures that a meltdown is impossible. The ceramics can withstand any temperature that might be reached in the event of a catastrophic cooling failure.
 
  • #280
The PBMR design uses a silicon carbide coating on the fuel elements, not graphite [where did that come from?]. Reading the links is recommended. There is no meltdown risk. The status of design reviews in the US can be found here:
http://www.eia.doe.gov/cneaf/nuclear/page/analysis/nucenviss2.html
 
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  • #281
Yes, we have no plutonium in our fuel pebbles today

Ivan Seeking said:
The ceramic approach seemed promising.
As far as I know, there is no such thing as a ceramic approach as regards PBMR fuel pebbles. The PBMR is a slow-neutron reactor. Slow-neutron reactors need neutron moderators. The PBMR uses graphite in its fuel pebbles to slow (moderate) the neutrons.



Ivan Seeking said:
In principle the separation between the Pu beads [pellet cores]
https://www.pbmr.com/3_pbmr_technical_info/pbmr_technical_contents.htm#PBMRFuel

--
The fuel particles (kernels) consist of uranium dioxide.
--



Ivan Seeking said:
The ceramics can withstand any temperature that might be reached in the event of a catastrophic cooling failure.
PBMRs, with their graphite fuel pebbles, can also withstand any temperature reached during a loss-of-coolant accident — provided there are no complicating circumstances. If burning jet fuel is dumped on the pebbles (which can easily happen since there is no containment shell for the reactor), they might burn and atmospherically-release tons of aerosolized high-level radioactive waste.
 
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  • #282
The tons of flammable graphite used in PBMRs

Chronos said:
The PBMR design uses a silicon carbide coating on the fuel elements, not graphite
https://www.pbmr.com/3_pbmr_technical_info/pbmr_technical_contents.htm#PBMRFuel

--
The coated particles are embedded in a graphite matrix as a 50 mm sphere, called the fuel zone.

Adding a 5 mm thick fuel-free graphite zone makes up the fuel sphere with an outer diameter of 60 mm.
--



Chronos said:
There is no meltdown risk.
If the graphite burns partly away, the fission fuel might become close enough together for a runaway reaction and subsequent meltdown to occur. Even of there isn't a meltdown, atmospheric fission-product release is possible if the graphite burns.
 
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  • #283
hitssquad said:
As far as I know, there is no such thing as a ceramic approach as regards PBMR fuel pebbles.

There was. Perhaps things didn't work out.
 
  • #284
If gasoline reaches $4.00 a gallon as hinted at by the Bush administration today... Even at $3.00 a gallon we are quicky approaching the point where alternative technologies can compete.
 
  • #285
Ivan Seeking said:
Those are not only silly questions, they are also already answered in the many links provided. Read and learn.

I don't think they are silly questions at all. all of those things you point to are supposedly sources of energy. Good; that's what we need is energy; so why go through the useless step of making hydrogen which we don't need; we need energy.

No amount of prestidigitation is going to evade the problem that we will have to use existing or new sources of energy to make hydrogen to do the same things we could do with that very energy withoput making hydrogen.

I believe it was Franz Kafka, who told a story about a region with a river running through it, and a town on each side of the river, both of them highly prosperous.

Everybody in the town on the west side of the river worked all day at the one factory in town, making marbles out of clay. They imported the finest finely ground clay materials and using the finest molding machinery that swiss engineering could devise, they cleverly molded that clay into perfectly spherical round marbles which the town exported to support all the population.

On the east side of the river, the second prosperous town also had but one factory where everybody worked. The factory had the finest German crushing machinerey that the human mind could conceive, and they all used those machines to produce the most beautiful finely powdered clay material from round marbles of the stuff that they imported in large sacks.

Everybody was kept happy, making hydrogen and then burning it.
 
  • #286
Seafang said:
I don't think they are silly questions at all. all of those things you point to are supposedly sources of energy. Good; that's what we need is energy; so why go through the useless step of making hydrogen which we don't need; we need energy.

The point that you seem to keep missing is that there are about a hundred links in this thread and linked threads that answer your questions. Many renewable energy sources are promising, or even succeeding in some markets. I'm not about to list them all again. If you read, you will see that they are already discussed in this thread, and the original archived thread, linked on page one. The real point here is to track the progress of various approaches and to see which are most practical. Also, as suggested by Chronos, even nuclear power may be a part of the solution.
 
  • #287
The Hydrogen Economy: Physics Today

Note: I think part but not all of this was previously posted and available online. Either way, in case you missed it...

If the fuel cell is to become the modern steam engine, basic research must provide breakthroughs in understanding, materials, and design to make a hydrogen−based energy system a vibrant and competitive force.

George W. Crabtree, Mildred S. Dresselhaus, and Michelle V. Buchanan
Since the industrial revolution began in the 18th century, fossil fuels in the form of coal, oil, and natural gas have powered the technology and transportation networks that drive society. But continuing to power the world from fossil fuels threatens our energy supply and puts enormous strains on the environment. The world's demand for energy is projected to double by 2050 in response to population growth and the industrialization of developing countries.1 The supply of fossil fuels is limited, with restrictive shortages of oil and gas projected to occur within our lifetimes (see the article by Paul Weisz in Physics Today, July 2004, page 47). Global oil and gas reserves are concentrated in a few regions of the world, while demand is growing everywhere; as a result, a secure supply is increasingly difficult to assure. Moreover, the use of fossil fuels puts our own health at risk through the chemical and particulate pollution it creates. Carbon dioxide and other greenhouse gas emissions that are associated with global warming threaten the stability of Earth's climate.

A replacement for fossil fuels will not appear overnight. Extensive R&D is required before alternative sources can supply energy in quantities and at costs competitive with fossil fuels, and making those alternative sources available commercially will itself require developing the proper economic infrastructure. Each of those steps takes time, but greater global investment in R&D will most likely hasten the pace of economic change. Although it is impossible to predict when the fossil fuel supply will fall short of demand or when global warming will become acute, the present trend of yearly increases in fossil fuel use shortens our window of opportunity for a managed transition to alternative energy sources.

Hydrogen as energy carrier [continued]
http://www.physicstoday.org/vol-57/iss-12/p39.html

For the pdf: http://www.physicstoday.org/vol-57/iss-12/PDF/vol57no12p39-45.pdf
 
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  • #288
Do you think fuel cells are ever going to compete against gasoline, Ivan?
 
  • #289
hitssquad said:
Do you think fuel cells are ever going to compete against gasoline, Ivan?

I would think so. The automotive designers are already heavily invested in fuel cell technologies, and with gasoline expected to reach as much as $4.00 a gallon soon... When we think about these things, we tend to think in terms of today's prices. Wait until gas here is $6.00 like in other countries. Also, as I have argued all along, if we include the real costs of oil, which includes war and many of the world's ills, fuel cells and alternative fuels are already cheap.

Of course [insert several explitives here] Bush favors making fuel cells that run on gasoline. :mad:
 
  • #290
Gasoline externalities and consumer preference

Ivan Seeking said:
if we include the real costs of oil
It is one thing to cite externalities, and another to imply that people consider externalities when making purchasing decisions. We are talking about whether fuel cells will ever compete against gasoline. Indicative of the lack of consumer motive for seeking alternative fuel technologies might be the facts that fuel-economical vehicles are persistently unpopular and that yearly vehicle miles traveled continually rises.
 
  • #291
First, as indicated, fuel cells and gasoline are not mutually exclusive. Next, orders for Hybrid vehicles are off the charts, in some case at least. As for your assertion that fuel economical vehicles are continually unpopular, I assume that you drive a Buick? It seems that you forget what we used to drive.

Also, test electric vehicles distributed by GM - the EV1 - were tremendously popular among those who were lucky enough [by their accounts] to get one. So I don't really see the basis for your arguments. Needless to say that this all neglects the coming reality of $4, and eventually $6 per gallon, and more. Finally, the ever increasing taxes on fuel are no accident, and externalities justify even more tax; much, much more.

The costs to all of us in money, environmental damage, health related issues and costs, which are huge btw, political agendas, military expenditures, etc, etc, and ultimately the cost in lives associated with the petro-economy are all very real. The benefits of an H2 economy - which appears to include H2 powered fuel cells - in all respects are equally real. So it not only makes sense on a personal/financial level, it makes sense from macro-economic and political perspectives as well; at the right time.

If you feel that alternative fuels are practical, but not fuel cells, I can only defer to the automotive engineers and designers who should know. They seem to feel that these will emerge as a practical technology. I think it will take time, and transitional technologies may be more practical; perhaps even H2 combustion engines, as some companies are working on this. I also liked your hydrogen pellets linked some pages ago. Those seem promising [edit] but I was concerned about the efficiency of the entire process. Of course, you bypass all sorts of problems by having a solid to transport and store, rather than a high pressure gas. So it seems to me that any additional energy costs in the production of these pellets might be recaptured in the distribution system.
 
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  • #293
hitssquad said:
Boron?
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.html

Hmmm, I may be mixing up your post with the pellets discussed in the Nova special. I thought that you had posted something very similar, but not Boron.


An intersting story today:
Windmills in the Sky
Australian engineer Bryan Roberts wants to build a power station in the sky -- a cluster of flying windmills soaring 15,000 feet in the air -- but is having trouble raising enough money to get the project off the ground.

After 25 years of research, Roberts has designed a helicopter-like rotorcraft to hoist a wind turbine high into the air, where winds are persistent and strong. The craft, which is powered by its own electricity and can stay aloft for months, feeds electricity to the ground through a cable.

Roberts, a professor of engineering at the University of Technology, Sydney, believes there is enough energy in high-altitude winds to satisfy the world's demands. Wind-tunnel data suggests a cluster of 600 flying electric generators, or FEGs, could produce three times as much energy as the United States' most productive nuclear power plant. [continued]
http://www.wired.com/news/planet/0,2782,67121,00.html?tw=wn_tophead_2
 
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  • #294
Solar Tower of Power Finds Home

The quest for a new form of green energy has taken a significant step with the purchase of a 25,000-acre sheep farm in the Australian outback. The huge alternative energy project isn't driven by manure, but by a 1-kilometer-high thermal power station called the Solar Tower.

Announced several years ago, the 3,280-foot Solar Tower is one of the most ambitious alternative energy projects on the planet: a renewable energy plant that pumps out the same power as a small reactor but is totally safe. If built, it will be nearly double the height of the world's tallest structure, the CN Tower in Canada.

..."Solar chimneys (towers) have become a hot area of research recently," said S.A. Sherif, a professor of mechanical and aerospace engineering at the University of Florida, who wrote several papers on the technology in the early 1990s and is the technical editor of the http://www.ises.org/ises.nsf/0/8eb9a73ea902c053c12568be004fa01a?OpenDocument . Although expensive to build, solar towers "essentially produce energy for free," said Sherif. In addition, the technology has been proven to work: A 650-foot solar tower was built in Manzanares, Spain, in 1981 by German structural engineers Schlaich Bergermann and Partner. Producing 50 kilowatts, it operated for seven years. But with oil prices at $15 a barrel in the mid-1980s, there was little interest in building a larger one, Sherif said. [continued]
http://www.wired.com/news/technology/0,1282,66694,00.html
 
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  • #295
Please see also the new posts above:

About H2 ICE: Internal Combustion Engines. They're here...
https://www.physicsforums.com/showthread.php?t=70653

Also, this seems to be a very cool site and one that I have never seen:
H2 CARSBIZ
http://www.h2cars.biz/artman/publish/index.shtml
 
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  • #296
I thought the general consensus a while back was the solar tower is bogus and a borderline urban myth. That basically its extremely tough to pump water to the levels described and the structure would be incredibly expensive to build along with other issues that would need to be carefully managed. Managed so well that most figures (as I recall) showed a negative energy output.
 
  • #297
Cliff_J said:
I thought the general consensus a while back was the solar tower is bogus and a borderline urban myth. That basically its extremely tough to pump water to the levels described and the structure would be incredibly expensive to build along with other issues that would need to be carefully managed. Managed so well that most figures (as I recall) showed a negative energy output.

I hadn't heard of this effort or what you describe. Could that have been something else? I didn't see that this would require pumping water.

It seems that Wired does push the edge a bit, but the claims of earlier efforts are quite specific.
 
  • #298
Cliff_J said:
I thought the general consensus a while back was the solar tower is bogus and a borderline urban myth. That basically its extremely tough to pump water to the levels described
It channels rising hot air which drives turbines. It doesn't use water:
http://www.wired.com/news/technology/0,1282,66694,00.html

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The Solar Tower is hollow in the middle like a chimney. At its base is a solar collector -- a 25,000-acre, transparent circular skirt. The air under the collector is heated by the sun and funneled up the chimney by convection -- hot air rises. As it rises, the air accelerates to 35 mph, driving 32 wind turbines inside the tower, which generate electricity much like conventional wind farms.
--
 
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  • #299
I only read last page and first two of this long thread, so hope i am not repeating. Most energy is in some form "solar energy" (coal old version, fission even older and not from our sun but earlier star) Only exception is tidal power. As many have pointed out, hydrogen is not an energy source. Most would prefer to live off the current solar input, stop burning fossil fuels, avoid nuclear, etc. The hydrogen economy could do so, but it will still take a lot of area as sunlight is not very concentrated. Few realize that solar cell generated electricity can not compete with the current sources even if the solar cells had zero cost the so called "BOS cost" (Balance of System) for land, structures, periodic repair,cleaning, conversion to AC from the DC generated, lots of interconnect wires, and a few other items are too expensive.

So what can one do? Use a natural solar energy collection system (sugar cane). It has about the same or slightly better efficiency than common economical solar cells (and the theoretical limit is 21% for any based on silicon, which is nearly ideal for the solar spectrum)

Production of a liquid fuel (alcohol) from sugar cane is easy and relatively cheap. The residue is good for feed to cattle, enrich the soil, and sequester carbon - I.e. removes CO2 from the air economically as only vegetation (green algie is "vegetation") can. Brazil were I live has been running cars on alcohol in large numbers for a couple of decades. Currently alcohol cost about R$1.20 /liter and gasoline about R$2.20 i.e. alcohol is much less costly and there is no funny economics in this. I don't have the current sales data but bet 9 out of 10 new cars sold in Brazil will run on alcohol.

Brazil would love to sell it to US and their well developed alcohol/ gas in any ratio motors. It is so cheap here because land and labor are cheap, the growing season is 12 months each year. Obviously the corn growing farmers of Iowa and their market for octane enhancement etc. "gasohol" would suffer if Brazil were allowed to export to US. Also important is fact that no Brazilian votes were available or of interested to a US government dominated by former oil company owners and related industry CEOs.

Never mind new hydrogen economy - get some real economy now with 20 year old Brazilian technology. Remove US import barriers.
 
  • #300
Cliff_J said:
I thought the general consensus a while back was the solar tower is bogus and a borderline urban myth. That basically its extremely tough to pump water to the levels described and the structure would be incredibly expensive to build along with other issues that would need to be carefully managed. Managed so well that most figures (as I recall) showed a negative energy output.
Are you thinking of the guy who wanted to pump fuel into space on a carbon nanotube tether/pipe?

No, as others have said, the solar tower idea just uses solare heating of the desert and would work - in theory. But that "in theory" part is a real kicker: The worlds tallest freestanding structure is about 500m high. They want to build a 1000m tower. Doesn't seem too realistic to me from an engineering standpoint.

Oh, and the other problem is that the company that's proposing it is a scam.

edit: I'm not a big fan of Wired - they publish a lot of crap, but this is a little rediculous:
But the purchase of the farm, which cost $1 million, near Mildura, Victoria, is a "very big step" in getting the project built, Davey said.

So far, the main impediment to building the tower has been the cost, with estimates ranging from $500 million to $750 million.
Hmm... obtaining 1/750th of the needed funding (guestimated) is "a very big step"?

And this land - at $185 an acre? I'm guessing its in the middle of nowhere.
 
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