Questions about a Hydrogen Economy; Scientific American

[Cliff_J]

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.

No I recall a discussion on here a long time back where the idea of some giant solar tower was proposed but rather than just use the heated air it also employed some use of water misting like a cooling tower. Some sort of method to increase the temperature differential to boost efficiency. Links to quite a few websites were provided, then the debunking started.

First the feasibility of such a tall and wide structure were addressed. I like watching the show "Extreme Engineering" and their ideas are wild enough, but those ideas are dwarfed by some structure nearly 20 miles across and over a half mile in height.

Second, the water was suppossed to be taken up to 2/3 the height to be deployed. The calcs for a column of water that high, the pumps needed and pumping losses, even just the pipe needed to contain that pressure were pushing available technologies. (makes sense with this about 2x as tall as the tallest buildings) Someone had done the numbers and showed the pumping requiring more MW than the design was suppossed to produce in total.

Third was the return on investment and cost to build. And now the extra question of would this structure be designed to handle terroristic acts too since its a symbol of captialism.

I dunno, I'd like to see a scale model working first with repeatability.

 

[Seafang]

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.

Well I am not missing anything; I have already read all the things you have alluded to; to the point where this whole thread has become exceedingly tiresome. Everybody seems to be trying to justify his or her particular pet form of "alternative" energy.
I'm in favor of ANY form of alternative energy sources.

What I am not in favor of is using scarce and expensive existing sources of energy that we desperately need to use for enterprise merely to repaint the gas tank a different color; because that is all that you are doing when you take existing fossil fuels and raw materials like water or hydrocarbons to extract at very high energy cost, the atoms of hydrogen you want to put in your newly repainted gas tank. It is simply a wheel spinning operation, and makes available NO new energy over and above what we still have left from available sources.

Exploit new sources of energy Yes I cheer for that. Waste existing sources of energy merely repackaging already scarce energy NO ! a thousand times NO!.

 

[Ivan Seeking]

Question from a member

The question is: How many nuclear power plants would be required to completely replace fossil fuels via H2 production for the US transportation sector?

I was shooting from the hip a bit but this should be a reasonable approximation. I'm sure that you will state any objections to the method used.

I used the following information. In the May 2004 edition of Scientific American,
http://www.sciamdigital.com/browse.cfm?sequencenameCHAR=item2&methodnameCHAR=resource_getitembrowse&interfacenameCHAR=browse.cfm&ISSUEID_CHAR=CB826BAE-2B35-221B-6E2587F29CF2C88A&ARTICLEID_CHAR=CB9BE5E6-2B35-221B-6F2461DEF9B52B9C&sc=I100322
The current “well to wheels efficiency” [WWE] of various fuels and applications are listed. For Crude oil used in internal combustion engines, the WWE is about 12%. For simplicity, I assume this as typical of all internal combustion engines.

Next, the total demand for crude was located here http://energy.senate.gov/legislation/energybill/charts/chart8.pdf
and is estimated to be about 13 million barrels per day for the entire US transportation sector.

Next, from the Energy Information Administration; International Energy Annual 2002, it appears the most crude comes with a total heat content of 5800 thousand BTUs per barrel. After converting [1055.056 Joules/BTU] etc, and after factoring in the 12% efficiency and the number of barrels per day demand, etc., I come up with a total of about 1.1 X 10¹¹ watts as the effective power demand.

If we consider water to H2 via electrolysis applied to hydrogen fuel cell powered electric cars, we expect a total well to wheel efficiency of about 8%. So we need 1.4 X 10¹² watts; or about 1100 nuclear power plants. This assumes 1200MW as the typical size of each nuclear plant.

If we use methane reformed to hydrogen via nuclear it gets more complicated. But it appears that the cracking process is the majority of the fuel chain energy loss, so a straight forward WWE is at least in the ball park. With this, it appears that by converting methane to H2, and again running a H2 fuel cell powered car, we would need about 420 nuclear power plants.

If these were applied to hydrogen internal combustion engines, considering only the efficiency of autos and using that as a worst case, we would need about 1.7 times as many nuclear plants in either case; or 1900, and 710 plants, respectively.

The initial calculations ignore aircraft and machines that cannot be converted to run on electric power. So the real number should lie somewhere between 1100 - 1900 for water to hydrogen, or 420 - 710 nuclear power plants in the case of reformed methane.

edit: error corrected

 

[willib]

Why would the amount of carbon in a gas give higher BTU value ??
http://www.naturalgas.com/consumer/measuring.html
bottom of page..

 

[Ivan Seeking]

More carbon means more bonds to break and form, hence more energy out. Ideally, all of the carbon atoms would bind as CO₂, which is what makes this all a net positive - exothermic - reaction. So as a rule of thumb, more carbon means more energy out per molecule.

 

[willib]

Oh ..Thanks Ivan..
i was doing some research today on the amount of natural gas we (our association) could save if we lowered the temp of our hot water heaters by one degree C..any way i came across a site that gave the specific heat of hydrogen to be something like 14,000 where the specific heat of water is 4.18 . it looked like hydrogen would make an excellent heat transfer mechinism..??
btw we could save 1090.9 CF of gas a month ,for a 500 gal hot water heater, if we lowered the temp by one degree C ..
I used a low number of the water heater comming on just five times a day..
( in reality it probably rarely goes off)

 

[willib]

and what about combined cycle gas turbines (CCGT )
http://www.energy.qld.gov.au/infosite/ex_comb_cycle_gt.html
do you mean to tell me that this whole time ,nuclear power plants have been wasting all that heat that goes into the cooling towers?
ps..
that is a general you , it is not geared twards anyone in particular..

 

[willib]

Ivan , is there any way to make methane ,from hydrogen? exothermic or endothermic?
maybe under high pressure , H2 will combine with carbon in nano tubes to give CH4 ??

 

[Ivan Seeking]

Why would you want to go the other direction? The whole point is to take the carbon out of the fuel chain.

It would take energy to break up the CO₂ and H₂O, and you would get less energy back when you allow the free carbon atoms to bind with free hydrogen, and the free oxygen to form O₂. So the reaction would be endothermic going the other direction. Also, the reaction in that direction is not spontaneous so it would be more complicated than that.

 

[hitssquad]

The whole point is to take the carbon out of the fuel chain.

What might be the purpose of taking carbon out of the fuel chain?

 

[willib]

WHY.??.because you said

More carbon means more bonds to break and form, hence more energy out

So i figured if one could use a more energy potent gas , then this whole thing might work..
thats all

 

[Ivan Seeking]

What might be the purpose of taking carbon out of the fuel chain?

Well that's a loaded question if I've ever heard one. Okay you tell me, why don't we want to remove carbon from the fuel chain?

Of course the answer to your question is global warming.

 

[Ivan Seeking]

Ah, I'll bet that you're thinking of the net zero carbon fuels - some of the biodiesel and ethanol options.

 

[willib]

Well that's a loaded question if I've ever heard one. Okay you tell me, why don't we want to remove carbon from the fuel chain?

Of course the answer to your question is global warming.

Global warming ?..! There have been many times in the past where the amount of carbon in the atmosphere has far exceeded the present..of course it is usually followed by a drastic drop in global temp. ice age ..
its just natures way of cleaning house i suppose..
my humble opinion..

 

[hitssquad]

The attractions of liquid hydrocarbon fuels

why don't we want to remove carbon from the fuel chain?

Carbon makes a convenient carrier for hydrogen; infrastructure is set up for liquid hydrocarbon fuels; and liquid hydrocarbon fueled engines satisfy relatively high machine performance standards.

Of course the answer to your question is global warming.

The answer is not noxious and smog-forming pollution?

 

[Ivan Seeking]

There are many reasons to remove carbon from the fuel chain. Yes, pollution is one reason, but greenhouse gas emissions are the primary concern.

If scientists magically declared an end to our global warming concerns, I would jump off of the hydrogen-only bandwagon in about five seconds.

 

[hitssquad]

Various definition of pollution

pollution is one reason, but greenhouse gas emissions are the primary concern.

Sometimes greenhouse gas emissions are referred to as "pollution."
http://www.google.com/search?q=greenhouse+gas+pollution

Do you know what equivocation is?

If scientists magically declared an end to our global warming concerns, I would jump off of the hydrogen-only bandwagon in about five seconds.

Perhaps global warming and its causes and social impacts should be addressed in another thread in another section of Physics Forums such as Earth and/or Social Sciences.

 

[Ivan Seeking]

Sometimes greenhouse gas emissions are referred to as "pollution."
http://www.google.com/search?q=greenhouse+gas+pollution

Do you know what equivocation is?

What is your point? You used the words noxious and smog-forming pollution, neither of which apply to CO₂ within the context of global warming.

Perhaps global warming and its causes and social impacts should be addressed in another thread in another section of Physics Forums such as Earth and/or Social Sciences.

The source article for this thread discusses greenhouse gases in fair detail. So it is completely on topic as far as technology options and motivations are concerned.

 

[hitssquad]

What is your point?

Pollution can mean -- and often is used to mean -- various different things. When a speaker specifies what he is referring to by his use of an equivocal term such as pollution, there is less confusion. Use of equivocal terms without differentiation is equivocation and is confusing. Lack of confusion is important for scientific communication. Arthur Jensen reports that elite scientists tend to be earnest about minimizing confusion in communication.

You used the words noxious and smog-forming pollution

That differentiates quite well from other forms of pollution, yes?.

neither of which apply to CO₂ within the context of global warming.

Yes. That is very clear, isn't it?

 

[Ivan Seeking]

I made my meaning clear when I said greenhouse gases and CO₂. If you have a point please make it.

 

[Ivan Seeking]

H2R Liquid Hydrogen powered BMW: Top Speed over 300 km/h

BMW Writes Automobile History and underlines Technological Leadership.

Hydrogen means top performance not only in rockets traveling to outer space:

...Indeed, the specifications of the H2R Record Car clearly confirm this superiority, the six-litre 12 cylinder power unit developing an output of more than 210 kW or 285 bhp. This accelerates the BMW prototype to 100 km/h in approximately 6 seconds and gives it a top speed of 302,4 km/h (185,52 mph). Based on the gasoline power unit featured in the BMW 760i, BMW's hydrogen combustion engine boasts the most advanced technologies such as BMW's fully variable VALVETRONIC valve drive. [continued]

http://www.germancarfans.com/news.cfm/NewsID/2040920.001/bmw/1.html

Edit: Note that this car can run on gasoline or liquid hydrogen with the flick of a switch. Also, according to one interview on Discoveries This Week, over the next few years, BMW expects there to be enough H2 fueling stations built in Germany to justify production of H2 powered cars. I don't know who's buying the hydrgoen now or what motivate the installation of these stations, but it sounds like Germany is hot on H2.

 

[willib]

The most significant differences in terms of the engine's structural components are the hydrogen injection valve and the choice of materials for the combustion chambers: Contrary to the production engine with fuel injected directly into the combustion chambers themselves, the injection valves in the hydrogen engine are integrated in the intake manifolds. And for the specific speed record requirements to be fulfilled in this case, the hydrogen combustion engine was designed and built for single-mode operation running exclusively on hydrogen.

the test car can not switch between gasoline & hydrogen

 

[Ivan Seeking]

Sierra Nevada Brews Up Environmentally Friendly Fuel Cell

...Designed to create energy without combustion, the 1 MW power plant consists of four 250-kilowatt Direct FuelCell(R) (DFC(R)) power plants from FuelCell Energy, Inc. (NasdaqNM:FCEL). Its waste heat will be harvested in the form of steam and used for the brewing process as well as other heating needs. One MW of electricity (equivalent to the power needed to support approximately 500-1000 homes for a year) will supply essentially 100 percent of the brewery's base load power requirements. With this power plant, Sierra Nevada not only lowers its overall energy costs but also eliminates air pollutant emissions equivalent to removing 500 gasoline-powered cars from the road every year. When the fuel cells generate more power than the brewery requires, Sierra Nevada sends excess electricity back to the grid system and receives credit for a portion of its generation costs. [continued]

http://www.rednova.com/news/science/190024/sierra_nevada_brews_up_environmentally_friendly_fuel_cell_electricity_gov/
and
http://www.alliancepower.com/sierra.html

 

[Kenneth Mann]

Promising?

This looks like a promising approach to hydrogen delivery. It still has development issues but they look solvable. What do you think?

KM

 

[Ivan Seeking]

SPECIAL REPORT: Thinking Beyond Oil

AS THE PRICE OF A BARREL OF OIL continues to surge and oil traders eye possible disruptions in production from hurricane Katrina, scientists are turning to the ocean as a possible source of alternative energy.

Many forms of renewable energy have been contemplated, and of course solar and wind power plants are already in use. But so far, only a small fraction of the world's energy production comes from renewable resources.

President George W. Bush has talked of a hydrogen economy, in which abundant energy would be extracted from water and the tailpipes of cars would be clean. But extracting hydrogen from water requires energy -- fossil fuels or nuclear power, for example. Many scientists say technology will never allow the extraction of a enough hydrogen to make up for the energy needed to do the extracting. ]continued]

http://www.livescience.com/technology/ap_050826_wave_energy.html

 

[hitssquad]

http://www.livescience.com/technology/ap_050826_wave_energy.html

"There's a real good chance that Oregon could turn into kind of the focal point in the United States for wave energy development and I think that would be a boon to the economy,'' said Gary Cockrum, spokesman for the Central Lincoln People's Utility District."

Everyone wants a research grant, Ivan.

 

[Ivan Seeking]

Thanks for the great insight.

 

[Ivan Seeking]

"Plug in your laptop to a cool hydrogen power source"

If you can't bear to be away from your laptop during that camping trip to deepest Borneo, help may soon be at hand. Lightweight generators powered by methanol are now on the market... for the rich, at least.

The device, designed to specifications for the US Army by the California company UltraCell, weighs just 1.3 kilograms when fuelled up and is the size of a novel. With a supply of 500 millilitres of methanol, the cell can chuck out 45 watts for a day, which is enough to power a laptop.

The cell and fuel together are half the weight of the lithium batteries needed to provide the same power.

Unlike traditional generators, fuel cells are totally quiet. And unlike batteries, they can be 'recharged' without being plugged into the wall. [continued]

http://www.nature.com/news/2005/050822/full/050822-8.html

 

[russ_watters]

http://www.livescience.com/technology/ap_050826_wave_energy.html

No offense Ivan, but when I see statements like these:

...in which abundant energy would be extracted from water... [uh, energy is not extracted from water]

and

Many scientists say technology will never allow the extraction of a enough hydrogen to make up for the energy needed to do the extracting. [but only those who understand the first law of thermodynamics ]

...I cringe. Its articles like that, where the writer misunderstands the 1st law of thermodynamics (and pretty much everything else about the subject she's writing about), that make people have unrealistic expectations of what hydrogen can do. Much of the rest of the article is a bunch of second-hand soundbytes of similar uselessness. Ie:

"I read something involved with this that said if 0.2 percent of the ocean's energy were harnessed, it could produce enough energy to power the entire world,'' added Cockrum, the utility district spokesman. [emphasis added]

"I read something..."? A reporter actually put that quote into an article? Jeez, did she take journalism 101? Terrible, terrible article.

The biggest difficulty facing us in the so-called energy crisis is bad information coming from government and the media, making people think wrong things about our energy situation. Ie, the nuclear power decline caused by misinformation following TMI.

 

[russ_watters]

...where the writer misunderstands the 1st law of thermodynamics (and pretty much everything else about the subject she's writing about)...

Holy crap, the writer is an electrical engineer?? What the...?

 

[Ivan Seeking]

No offense Ivan, but when I see statements like these: and ...I cringe.

What exactly is your objection? If the energy is not in the water ala wave energy then where is it? And you seem to be objecting to the notion that we need need energy to "extract" hydrogen. I mean, I don't have any vested interest in livescience, but the meaning seemed pretty clear to me. Maybe you misunderstood.

 

[Ivan Seeking]

Okay, I think you are reading this wrong. You were thinking the article is about extracting H2 from water for energy?

 

[LURCH]

Actually, I think he's reading it right, if he's talking about this segment:

President George W. Bush has talked of a hydrogen economy, in which abundant energy would be extracted from water and the tailpipes of cars would be clean. But extracting hydrogen from water requires energy -- fossil fuels or nuclear power, for example.

which is definitely talking about extracting hydrogen from water. And the other statement,

Many scientists say technology will never allow the extraction of a enough hydrogen to make up for the energy needed to do the extracting.

seems a bit silly to me,as well. "Many scientists say"? No, the law of entropy, arguably the most verified and inescapable truth of the physical universe, says. This isn't a question of "...technology will never allow...", but the physical laws of reality will never allow.

I am somewhat hopefull that the new breakthrough in carbon nanotubes will at least partially solve some of the most outsanding storage problems.

 

[Ivan Seeking]

Well, according to the article in the OP, it's not so clear cut since the complete well-to-wheels efficiency of the system has to be considered. For example, it is more efficient to crack the hydrogen in methane and run that H2 in a Hydrogen fuel cell, than it is to run methane directly in methane fuel cells.

In either case, this article is about using ocean wave energy and the continued talk of the Oregon coast being a great focal point for this effort. The logical connection to H2 is that wave motion energy probably lends itself well to producing [cracking] H2. If I were an engineer wanting to work in this industry, I would sure want to know about the work in Oregon.

Not to mention that I am, I do, I'm here, so I hope to.

 

[Ivan Seeking]

btw, I have worked with Prof von Jouanne, and not only is she is a class act [having helped me to get my business going in the very early days], she is also very, very smart. She did a lot of work that help to solve the problem with VFD induced motor failures, and she allowed me to use some of her work [equations] to solve some problems that I had with a related technology. But in any event, I would chalk up any misstatements to LiveScience; or perhaps nerves.