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Old 09-21-07, 12:50 PM   #1
permanentjaun
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Chemists - How much energy does it take to make hydrogen?

Just a quick thought. Wouldn't it be cool if your trainer at home wasn't a fluid or magnetic trainer but one based on creating hydrogen? As you turn the pedals you create the current to split water into hydrogen and oxygen. I think it'd be real neat if the trainer was then attached to a device to capture the hydrogen.

Is hydrogen the energy answer though? If it is, I think this would be a nice way to get it. Individuals would be responsible for their energy needs and ultimately societies fitness levels would benefit as well. Wouldn't it be cool if you went over to your neighbor and asked, "hey, you got any hydrogen I can borrow?" If we could produce even just 100 watts for an hour on a trainer, would this be able to create enough hydrogen to power a car for 50 miles?

Just a thought.

PS - This idea was inspired by Specializeds innovate or die campaign on their website. Their demo innovation was a simple dc generator attached to a trainer that went to an ac inverter to make power for a computer. I just tweaked the idea a bit. http://www.innovate-or-die.com/

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Old 09-21-07, 01:10 PM   #2
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I ain't no chemist or physicist or nuthin', but wouldn't you have to have a fusion reactor to make use of the hydrogen for energy purposes? If so, it would take one hell of a rider to produce any measureable energy at all, as it takes a whooooole bunch of energy (like a serious laser - and I mean serious laser) to get hydrogen to fuse into helium, not to mention all the containment problems. And even thenn, I don't think anyone has achieved "break even" yet (where ytou get as much useable energy out of the reaction as you put into making it happen).

Of course, I could be wrong or outdated. Phantomcow2, consider researching this to be your next homework assignment, due Monday.
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Old 09-21-07, 01:11 PM   #3
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or you could run an alternator off the trainer and store the electricity in a battery.
Average person could probably do between 100 and 200 watts for an hour. This could be stored in a deep cycle 12V battery, and if you needed 110volts, hook up a modified sine wave converter, and voila 110v AC current.
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Old 09-21-07, 01:14 PM   #4
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Heat energy:
1 kilo watt hour of electricity = 3413 BTU
1 gallon gasoline = 125,000 BTU

Most riders generate around 0.2 KW (200 watts). 682 BTU per hour.

You could run your TV with the bike power, though.
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Old 09-21-07, 01:17 PM   #5
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or you could run an alternator off the trainer and store the electricity in a battery.
Average person could probably do between 100 and 200 watts for an hour. This could be stored in a deep cycle 12V battery, and if you needed 110volts, hook up a modified sine wave converter, and voila 110v AC current.
Yea that just struck my head too. Some questions I would have however are, is that the most efficient way to store the energy. The problem with batteries is they take forever to build up and can only store so much energy. That's why a lot of the 100% electric cars of today only have ranges of at most 300 miles and then need hours to recharge. You're also limited by the size of the battery you're using. Whereas if you split the hydrogen and oxygen you can store the hydrogen immediately and you're only limited by the size of the tank you put it in. Say you had a tank the size of a water heater in your house, I predict that would be able to more cheaply store more energy than an expensive battery that could hold similar amounts of energy.

This is where we need chemists and physicists to chime in. I understand energy is lost when you transfer it from one form to another, but I think splitting water into hydrogen would be more efficient than storing directly in a battery. Plus I think it'd be cool if then you could decide what you want the energy to be used for. Do you heat your house? Power your vehicle? Heat your pool? Run a power generator?
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Old 09-21-07, 01:18 PM   #6
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Heat energy:
1 kilo watt hour of electricity = 3413 BTU
1 gallon gasoline = 125,000 BTU

Most riders generate around 0.2 KW (200 watts). 682 BTU per hour.

You could run your TV with the bike power, though.
A small LCD screen or your PC. You could even run lights in the house if they are low wattage, high efficiency type like LED lights.
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Old 09-21-07, 01:20 PM   #7
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Heat energy:
1 kilo watt hour of electricity = 3413 BTU
1 gallon gasoline = 125,000 BTU

Most riders generate around 0.2 KW (200 watts). 682 BTU per hour.

You could run your TV with the bike power, though.
This is where I get confused, because yes one kwh is 3413. Alright, how much hydrogen can you produce from water with 682 btu per hour? I see the hydrogen as being stored energy just as oil is. So while you produce only 682 btu's, you create x amount of hydrogen which holds maybe 50,000 btu's. You're not creating energy since the energy was always there in the water. Sort of like how a small spark in a gas engine releases a lot of energy in the gasoline.
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Old 09-21-07, 02:13 PM   #8
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It requires energy to split water into hydrogen and oxygen. You get about the same energy back when you burn the hydrogen, creating water again.

It's really no different than charging a battery.
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Old 09-21-07, 02:16 PM   #9
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I'm no chemist, but I know that if I eat a burrito before I hop on the trainer, I'll liberate more methane than pure hydrogen.
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Old 09-21-07, 02:25 PM   #10
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This is where I get confused, because yes one kwh is 3413. Alright, how much hydrogen can you produce from water with 682 btu per hour? I see the hydrogen as being stored energy just as oil is. So while you produce only 682 btu's, you create x amount of hydrogen which holds maybe 50,000 btu's. You're not creating energy since the energy was always there in the water. Sort of like how a small spark in a gas engine releases a lot of energy in the gasoline.
You can't burn water, and no intermediate compound can change that.

http://www.science.uwaterloo.ca/~cch...c120/hess.html
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Old 09-21-07, 02:25 PM   #11
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You could make a nice battery charger with a trainer, one would think. Rectifier - regulator - charger - battery. Unfortunately your cell phone manufacturers charger might need to include the generator into its control loop.
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Old 09-21-07, 02:33 PM   #12
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You can't burn water, and no intermediate compound can change that.

http://www.science.uwaterloo.ca/~cch...c120/hess.html
We're not burning water. I forgot the name of the process but have it now; electrolysis. "Electrolysis is a method of separating bonded elements and compounds by passing an electric current through them."

So that's my question. If an avg cyclist could produce 100-200 watts of electricity over an hour. How much hydrogen would they be able to make through electrolysis?
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Old 09-21-07, 03:39 PM   #13
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We're not burning water. I forgot the name of the process but have it now; electrolysis. "Electrolysis is a method of separating bonded elements and compounds by passing an electric current through them."

So that's my question. If an avg cyclist could produce 100-200 watts of electricity over an hour. How much hydrogen would they be able to make through electrolysis?
You're still trying to burn water indirectly by making an intermediate compound (hydrogen).

If you want to know how much hygrogen gas you could make from 200W it's less than 5g/hour
water Hf = -285.8KJ/mol
1W = 1J/s
200J/s x 3600s/hour = 720,000J/hour
720,000J/hour / 285,800J/mol = 2.5mol/hour
2.5mol/hour x 2g/mol = 5g H2/hour

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Old 09-21-07, 04:26 PM   #14
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Oh oh and hook up the oxygen to a face mask, make some fuel, and have an oxygen bar, AND exercise.
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Old 09-21-07, 04:53 PM   #15
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What might make more sense is to generate electricity which you put into your house panel. So while you're using the bike your offsetting the power used from the grid by what you make on the bike. (assuming this is all possible)
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Old 09-21-07, 05:12 PM   #16
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I promise you it is possible to burn water. Inside water is stored energy, in the form of hydrogen. What electrolysis does is put energy in to extract that stored energy. Unfortunately, it requires more energy to put in than you actually extract. Stan Meyers developed a system, which has been replicated, which makes this untrue. http://www.youtube.com/watch?v=bqfiA...elated&search=
http://www.youtube.com/watch?v=u9XrL...elated&search=
http://www.hotlinkfiles.com/browse/waterfuel/42765

http://befreetech.com/media/stan_meyers_bb.wmv

Hydrogen is a very viable energy source. It improves the performance of ICE's greatly. The key is probably not to store the hydrogen, but to generate it on demand.
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Old 09-21-07, 05:13 PM   #17
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And it's definitely possible to run some electrolysis using your trainer. In fact, you should simply remove whatever device you have to generate resistance and replace it with a good sized motor, or a car alternator. Use your energy to drive that alternator.
When you are on the trainer, that's wasted energy. Harness it all!
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Old 09-21-07, 05:14 PM   #18
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By the way, 200watts is a decent amount, assuming you're talking 200 electrical watts. I ran some electrolysis experiments at home and got great results with 200 watts. I believe it is the amperage that counts more tahn the voltage though. By the way, the Stan Meyer system does not require any electrolyte in the water.
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Old 09-21-07, 05:20 PM   #19
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I promise you it is possible to burn water. Inside water is stored energy, in the form of hydrogen. What electrolysis does is put energy in to extract that stored energy. Unfortunately, it requires more energy to put in than you actually extract. Stan Meyers developed a system, which has been replicated, which makes this untrue. http://www.youtube.com/watch?v=bqfiA...elated&search=
http://www.youtube.com/watch?v=u9XrL...elated&search=
http://www.hotlinkfiles.com/browse/waterfuel/42765

http://befreetech.com/media/stan_meyers_bb.wmv

Hydrogen is a very viable energy source. It improves the performance of ICE's greatly. The key is probably not to store the hydrogen, but to generate it on demand.
You're not burning water; you are obtaining the energy you chemically stored in the form of hydrogen.

Why do people ask questions if they are just going to ignore the answer because it doesn’t fit their fairy tale? Read the Hess law link I provided.

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Old 09-21-07, 05:21 PM   #20
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the amount of food and water you would need to consume, to create any usable amount of hydrogen, would offset any benefit. net result would be negative impact on resources
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Old 09-21-07, 05:28 PM   #21
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What might make more sense is to generate electricity which you put into your house panel. So while you're using the bike your offsetting the power used from the grid by what you make on the bike. (assuming this is all possible)
Sure it's possible. You can get a solar-power system for your house and use your trainer to charge the batteries as well. Regulations in a lot of areas require you to hook up that system to the local power-grid and sell them your excess power-generation at a discount.

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Old 09-21-07, 05:29 PM   #22
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You're not burning water; you are obtaining the energy you chemically stored in the form of hydrogen.

Why do people ask questions if they are just going to ignore the answer because it doesn’t fit their fairy tale? Read the Hess law link I provided.

I’m done with you morons.
Phantom is right in that you can electrolyze water to produce hydrogen. And you are right in that you are essentially supplying the gibbs free energy to release the calorific value of hydrogen. Everybody chill K
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Old 09-21-07, 05:37 PM   #23
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I violently attack ignorance in all its forms.

Nobody doubts you can make hydrogen gas from water, or burn hydrogen gas. It’s this free energy hippie crap that annoys me.
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Old 09-21-07, 05:44 PM   #24
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How about this?

Assuming you can produce 682 BTU per hour and there is no loss in the electro-mechanical electrolysis system, you will produce X amount of hydrogen per hour. However, X amount of hydrogen will only give you back 682 BTU in the ideal (i.e. not real world) situation. To that effect, hydrogen is only acting as a storage mechanism.

In real life, the efficiency of conversion is not unity so there will be losses in the conversion from water to its elements of hydrogen and oxygen. Burning hydrogen for energy via heat is also very inefficient, and you will have significant losses there also. Finally, hydrogen and oxygen are gases. That means storage is quite challenging. If you want to have efficient storage, you need to compress them. Obviously, the compression, and then subsequent decompression prior to use also do not score well on the efficiency chart. In the end, really, hydrogen as a fuel is really more or less a pipe dream now.

Having said that, I read somewhere that someone is researching on how to get plants to produce hydrogen gas directly from photosynthesis. Essentially, they are attempting to use genetically engineered plants to produce hydrogen gas using sunlight. You still have the storage/compression/decompression loss but it makes hydrogen as a fuel a little more feasible.

(Suggestion: Please read up on thermodynamics)

Last edited by Mr. Fly; 09-21-07 at 05:45 PM. Reason: Addition of suggestion to help with discussion
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Old 09-21-07, 05:47 PM   #25
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the amount of food and water you would need to consume, to create any usable amount of hydrogen, would offset any benefit. net result would be negative impact on resources
But since you would have been on the trainer anyways, those resources have already been used.
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