Hydrogen Power

[arcticpenguin]

It certainly SOUNDS like a safety issue, and the spreading of the hydrogen afterwards is icing on the cake.

/orders asbestos underwear

At least hydrogen dissipates more quickly than any other gas. and does not hang out in low-lying areas like gasoline vapor.

 

[fishbob]

5000 psi is less than twice the pressure contained in an aluminum scuba tank. So a series of small 5000 psi tanks would do it, and could look a lot like basic scuba tanks.

.25 cubic meters of H2 would require somewhere around 20 scuba sized tanks, at about 50 lbs each = about 1000 lbs. This vs 20 gallons of gasoline or diesel @ about 6.5 to 7 lbs/gallon plus the fuel tank weight, about 200 lbs.

I doubt that H2 gas is any more dangerous than gasoline, for carrying around in a vehicle. Gasoline vapor accumulates in low places, H2 gas dissipates upwards quickly.

 

[Badger]

Correct me if I'm wrong, but it seems that TillEulenspiegel's proposal would be ideally suited to home or industrial use, rather than a vehicle.

I mean, if I could paint my house with stuff, and have a couple of wires leading to a tank of water in the basement which I plug my appliances in to, that sounds like quite the deal to me!

I think the main problem with applying alternative energy sources to transportation begins with the internal combustion engine. There is a huge amount of wasted energy that is disappated as heat (friction and from combustion) and noise. Another factor is the operational range as opposed to the point where the motor runs at maximum efficiency. IIRC, internal combustion engines are about 20% efficient in that 20% of the energy in the fuel makes it to the output shaft of the engine. Less makes it to the rear wheels. I have heard that turbines are more efficient, in the 40% range, but haven't done enough research to be confident of that. And I don't know where rotary engines (wankles) fall in there, either.

So the main concern is getting the energy from the sun (because no matter what you're talking about, excluding nuclear power) you're converting solar energy into motion, when you get right down to it.

My preference would be for a diesel engine (turbine? IC? Rotary) driving a generator at the most efficient speed/load for that engine/generator set, and taking the electricity to motors at the wheels, and offloading extra energy to a form of battery storage in the vehicle itself. The batteries will provide power for acceleration/load, while the generator will provide power for constant speed. Of course there would be electric braking as well which would provide some battery recharge, and I guess you could paint it photovoltaic as well, and plug it in to the ol' basement watertank at night. But that's just my preference.

With regard to the fuel for the engine in the setup above, I guess it doesn't really matter if it's deisel, gasoline, hydrogen, chickenfat, home brew, ethanol, or what. My point is that there are many energy sources now, but they need to be examined in a different way in order to turn sunlight into motion.

 

[BrilliantBeast]

Interesting things happen when you start a thread, get busy, then go back to it.

Revising my initial question, it looks like I had the wrong issue, the issue is not pollution, but energy independence. In light of that, the analogy of two apples for one apple holds.

 

[Agammamon]

A better analogy may that you want an apple but you have two oranges to trade.

It boils down to a matter of efficiencies and energy densities.
Solar power is cheap but it takes a lot of surface area to generate power.
Fuel cells may not be as overall efficient as solar power but they store what energy they have in a more compact form. More compact than batteries. Also, fuel cells can be fueled faster than high capacity batteries can be charged.

So you spread your solar cells out in static locations, where size doesn't matter. Use that to crack water and store the H2/O2 in the car, where it is recombined in the fuel cell. Eventually the mass/capacity ratio and charge times of batteries may exceed fuel cells, in which case you just stop using fuel cells.

 

[arcticpenguin]

Solar power is cheap but it takes a lot of surface area to generate power.

Current solar cells are not that cheap. Break even times are a couple of decades.

 

[chipotle]

energy density of h2

Good info at:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html

The H2 storage problem does have a simple solution. Add carbon to the H2 so you get a denser, less volitile fuel that does not have the embrittlement problems of H2. Something like C8H15 fould work fine. An added benefit would be that this fuel would work in existing cars.

 

[aerocontrols]

Re: energy density of h2

Good info at:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/electrol.html

The H2 storage problem does have a simple solution. Add carbon to the H2 so you get a denser, less volitile fuel that does not have the embrittlement problems of H2. Something like C8H15 fould work fine. An added benefit would be that this fuel would work in existing cars.

oh, LOL!

I just had to read that out loud to my office buddies.

 

[Mr. Skinny]

It certainly SOUNDS like a safety issue, and the spreading of the hydrogen afterwards is icing on the cake.

/orders asbestos underwear

Hydrogen ignites so readily, it's unlikely to spread out and then explode. I've read that the energy generated by the hydrogen molecules escaping through a pinhole leak in a tank is sometimes enought to ignite it. Add that to the invisible flame, and it can be scary stuff.

Years ago I did the safety work on a hydrogen burning prototype aircraft engine supplied by two tube trailers (semi sized) of gaseous hydrogen. It took nearly eight years to work all the issues, many of which were safety related.

That said, it will be interesting to see what creative ways can be developed to handle/distribute hydrogen safely.

 

[jj]

Re: Re: energy density of h2

Sorry, but you need to go a bit farther. All of that carbon will require more oxygen to burn, so you need to add a bunch of NO3's to it.

Perhaps 1,3,5,7 Tetra dinitro octane, perhaps?

 

[arcticpenguin]

Someone want to take a look at this?

http://www.sciencedaily.com/releases/2003/06/030626235144.htm

ARLINGTON, Va. — Scientists have developed a hydrogen-making catalyst that uses cheaper materials and yields fewer contaminants than do current processes, while extracting the element from common renewable plant sources. Further, the new catalyst lies at the heart of a chemical process the authors say is a significant advance in producing alternate fuels from domestic sources.

In the June 27 issue of the journal Science, James Dumesic, John Shabaker and George Huber, of the University of Wisconsin at Madison, report developing the catalyst from nickel, tin and aluminum and using it in a process called aqueous-phase reforming (APR), which converts plant byproducts to hydrogen. The process performs as well as current methods that use precious metals such as platinum, yet runs at lower temperatures and is much cleaner.

 

[chipotle]

Boring

Normal decomposition produces methane, which is denser and safer than H2. Why would anyone want to produce H2 instead of CH4? You can always trade the safer CH4 for CO2 and H2 later on.

 

[arcticpenguin]

Here is an article on fuel cells for aviation. There's something about designing a fuel cell to use jet fuel isntead of H2 for use as an auxiliary power unit, to run the electrical equipment aboard the aircraft.

There's also mention of a solar/fuel cell combo, but I don't think this would be currently anywhere near practical for the lifting capacity and speeds of passenger aircraft.

 

[arcticpenguin]

http://story.news.yahoo.com/news?tm...&u=/nm/20030718/sc_nm/environment_hydrogen_dc

WASHINGTON (Reuters) - Two U.S. energy experts cast more doubt on Friday on a push to develop hydrogen-powered cars as a means to cut air pollution and reduce oil imports.



Cheaper and faster ways already exist to achieve the same effect, including raising fuel efficiency and toughening environmental standards, David Keith and Alexander Farrell, wrote in Friday's issue of the journal Science.

"Hydrogen cars are a poor short-term strategy, and it's not even clear that they are a good idea in the long term," Farrell, assistant professor of energy and resources at the University of California, Berkeley, said in a statement.

"Because the prospects for hydrogen cars are so uncertain, we need to think carefully before we invest all this money and all this public effort in one area."