Posted on 05/14/2007 7:19:54 AM PDT by SunkenCiv
Where does the hydrogen come from?
5 kilos = 280 liters (70 gallons).
Your outburst is just like a toddler throwing a tantrum in the toy aisle at this point - pathetic.
Showing something is possible doesn’t show that it is practical. It’s possible to go to the Moon, but it isn’t practical.
Yup. I told Orville and I told Wilbur, that thing'll never fly.
Obviously your ridicule was directed toward the pie-in-the-sky set who deny that problems with hydrogen — the most glaring perhaps being the need to produce it from something — rather than toward me.
“Buuuuuuuuuung! Yer Keghole! where the wind come sweepin’ down the plain...”
(that suddenly came to mind for some reason)
“Describes two major problems with hydrogen. Energy required to liquify it (or compress it a reasonable amount) and equipment required to store it in any usable form. Of course handling liquid or high pressure hydrogen would not be practical for anyone other than trained professionals.”
The best and most dense way to store hydrogen is - drum roll - in a hydrocarbon! Gasoline!
The only other real option is storing it as an attached hydride, but then you have to get it to bind and unbind which requires energy and equipment too.
Not to mention that hydrogen embrittles steel, burns with an invisible flame, etc.
Ain’t no engineers pushing hydrogen, unless they are getting an R&D handout from the government.
5 kilos of liquid hydrogen ~ 71.4 liters = 18.85 gallons.
We have diesel and gasoline fuel distribution now. Parallel fuel distribution has been a fact for decades. why therefore would anyone need to get rid of a functioning combustion engine vehicle? That is a straw man.The fact is that there's no parallel fuel distribution infrastructure for hydrogen that is worldwide, and building one will not be cheap. It could very well be much cheaper to build facilities which produce liquid hydrocarbon fuels from various electrical sources and continue to use the existing infrastructure and the types of vehicles which use it.
“The US Department of Energy (DoE) has set a series of advisable targets that a hydrogen-fuelled vehicle should meet in order to be economically viable: by 2010, the storage system’s capacity will need to be greater than six per cent hydrogen by weight, for example.
“Schröder’s team shows that their frameworks reach this requirement, and come close to the DoE’s volume-density target of 45 grams per litre. In fact they have achieved the highest percentage hydrogen uptake of any such material thus far reported.”
Bigger is not necessarily better — in hydrogen storage
September 22, 2006
http://www.physorg.com/news78141222.html
This cryogenic hydrogen would always be boiling away, which would create concerns for those who have to leave their cars parked for any length of time, and which would also turn the atmospheres in underground or otherwise enclosed parking garages into explosive fuel-air mixtures.
Showing something is possible doesn’t show that it is practical. It’s possible to go to the Moon, but it isn’t practical.
Attempting to revise what the article claimed? It claims things that are demonstrably false, and it did indeed imply impossibility. Nice try.
How do you deal with the question of continuous venting?
If you park a liquid Hydrogen vehicle in a garage attached to your house is that a good idea?
Special purpose vehicles with organized and trained personnel operating them is a lot different from a family with 2 beaters in the driveway (garage?)
89. Just a few numbers to put this in perspectiveWhether this concept happens or not depends on how efficient the process is from end to end. Is the value of the energy-out significantly higher than the cost and performance of the system as a whole? That would include solar panels, electrolyzing, storage of hydrogen, and efficiencies of fuel cell and electric motors. One thing to remember is that the hydrogen gas you electrolize from water cannot be used directly, it must be either highly compressed or liquified for storage and transport, both requiring significant energy.
IDemo
Fri Nov-25-05
DemocraticUnderground
Let's look at a few numbers.
A one kilowatt solar system (about 10-12 solar modules) requires about 100 square feet of installation area. If you completely cover your rooftop, let's say ~1000 square feet,you get 10kW. So on an eight hour day of strong sunlight, you get about 8 * 10kW/hrs of energy. That's at maximum insolation (incoming solar radiation).
The efficiency of hydrolysis has been widely reported between 50 and 80% or higher, but 65% seems to be a good working number. That leaves us with .65 * 80, or 52kw/hrs worth of hydrogen gas.
Now comes the hard part. In order to get the hydrogen into our vehicle, we must either highly compress it or liquify it.
Read:"The laws of thermodynamics dictate the amount of energy it takes to compress a gas. The physical properties of hydrogen make it the most difficult of all gasses to compress. At 800 bars, a perfect, single stage compressor consumes energy equal to 16% of the chemical energy in the hydrogen. (This is the energy that gets instantly released in the event of a tank failure.) It is possible to use a multistage compressors with intercoolers to achieve 12%. This is an estimate extrapolated from an actual multistage compressor working at 200 bars. A multistage compressor working at 800 bars does not exist.
It is technologically challenging to compress hydrogen to 800 bars. Higher pressure would not result in much volume reduction. At these pressures, hydrogen acts less like a gas and more like a liquid.
The laws of thermodynamics also dictate that energy losses occur when hydrogen is transferred from a storage tank to a vehicle. The design of the transfer lines and the pressure fittings is critical in keeping energy losses low."
LIQUID HYDROGEN
"Liquifying the hydrogen reduces the volume to be transported but at an even higher energy cost. Firstly to transform electricity into liquified hydrogen requires energy equivalent to about half the energy in the hydrogen. Liquid hydrogen is four times the volume for the same amount of energy as petroleum. Furthermore energy must be used to keep the hydrogen at -253 degrees C. Overall energy consumed in storage is around .3% per day, i.e., to store hydrogen for the six months from summer to winter would use up energy equivalent to more than half the stored energy. Further losses would occur at filling points and through valves and joints. In addition the hydrogen tends to boil off at 3% per day, although this can be used, unless the device, e.g., car, is idle for several days at a time."
So now let's say you have obtained the necessary equipment to convert your hydrogen gas to its cryogenic (liquid) form at minus 253 degrees C (that's -423 degrees Fahrenheit), and to store it safely. At roughly 50% efficiency, you now have .50 * 52kW/hrs, or 26kW hrs of energy to work with. That sounds like a ton of driving time to me, but wait, more math (aargh!). The electric motor may be up to 90% efficient, leaving you with 23.4 kW/hrs. One horsepower equals about 746 watts. If your fuel cell vehicle uses a motor with only an 80-horse output, it uses 80 * 746, or 59.68 kw of power, or 59.68kw/hrs of energy. This leaves you with just over 23 minutes of daily drive time for one vehicle, with none left over for powering your house. All at a total cost that likely (now) exceeds your house.
And that's with 8 hours of LA quality sunshine, every day.
Best to stick with plug-in hybrids and battery electric vehicles for the time being.
LOL Classic!
Nice try, your nasty remark was directed at me.
Now if you'll excuse me, I have to hurry so I won't be late to my next meeting, where's we're protesting these crazy things called "antibiotics", since everyone knows you'll never, ever be able to treat illnesses that way. What will these people try to pull over on us next?
By the way, you do realize that for many of us, bunging a keghole simply keeps the good stuff from coming out of the keg.
Do you know the process they use to produce the liquid hydrogen? How to they transport it and store it aboard the bus? I'm curious because temperature/pressure considerations pose considerable problems when handling usable quantities of hydrogen.
Yes, the author conveniently ignored hydrides, didn’t he ?
Hydrides carry more hydrogen by weight and volume than liquid hydrogen, with none of the high-pressure or cryogenic tank issues. You can carry it around in a pail.
Cost and efficiency may never work, but to claim that there are only two ways to carry hydrogen — compressed or liquified — is disingenous.
Although his fixation on the problems of compressed or liquified hydrogen are a smokescreen, doesn’t he have a point about creating the hydroge in the first place ?
If the goal is less CO2, the reformation is not a good way to create hydrogen. If the goal is an economical energy carrier, then electrolysis is very expensive.
I think people overlook the fact that a “fuel-cell” vehicle is really just an electric vehicle that gets its electricity from a fuel-cell rather than a battery. And battery/ultra-cap systems are less complex, more efficient, and an infrastructure exists.
I’m amazed the author ignores the electric-vehicle aspect of fuel-cell vehicles entirely, and poses methanol and ethanol combustion vehicles as a better alternative to future transportation needs.
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