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Old 05-08-2007, 10:44 AM   #1
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Hydrogen epiphany

I always thought that using on board electrolysis to generate hydrogen fuel for an engine is counterproductive......there are energy losses all over the freakin' place: belt losses, generator losses, electrical resistance, electrolysis losses etc.

But it occurred to me that hydrogen could be a way to regenerate and store braking energy. Here's the strategy:

1) The hydrogen electrolysis cell activates only when the brake pedal is pushed. Braking energy is converted into chemical (hydrogen) energy.
2) Hydrogen accumulates in a tank or bladder during decelleration and (perhaps) during idle.
3) When the gas pedal is pushed, a solenoid valve opens, allowing the accumulated hydrogen to enter and help fuel the engine.

The hydrogen recovers braking energy and uses it to help power the car, just like hybrids do. This scheme does away with the expensive and heavy batteries, electric motors and electronics now used in hybrids.

Ford developed a hydrogen powered internal combustion engine powered prototype car. But pure hydrogen powered vehicles, whether fuel cell or ICE, have always been impractical because of the high pressure storage tanks that are needed to perovide good range. Another benefit of hydrogen regeneration is that it doesn't need to store much hydrogen (maybe a few cubic feet at atmospheric pressure). It only stores what's created and used during each decelleration / accelleration cycle.

Have any Gassaver hydrogen tinkerers tried this?
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Old 05-08-2007, 12:20 PM   #2
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Originally Posted by Sludgy View Post
I always thought that using on board electrolysis to generate hydrogen fuel for an engine is counterproductive......there are energy losses all over the freakin' place: belt losses, generator losses, electrical resistance, electrolysis losses etc.

But it occurred to me that hydrogen could be a way to regenerate and store braking energy. Here's the strategy:

1) The hydrogen electrolysis cell activates only when the brake pedal is pushed. Braking energy is converted into chemical (hydrogen) energy.
2) Hydrogen accumulates in a tank or bladder during decelleration and (perhaps) during idle.
3) When the gas pedal is pushed, a solenoid valve opens, allowing the accumulated hydrogen to enter and help fuel the engine.

The hydrogen recovers braking energy and uses it to help power the car, just like hybrids do. This scheme does away with the expensive and heavy batteries, electric motors and electronics now used in hybrids.

Ford developed a hydrogen powered internal combustion engine powered prototype car. But pure hydrogen powered vehicles, whether fuel cell or ICE, have always been impractical because of the high pressure storage tanks that are needed to perovide good range. Another benefit of hydrogen regeneration is that it doesn't need to store much hydrogen (maybe a few cubic feet at atmospheric pressure). It only stores what's created and used during each decelleration / accelleration cycle.

Have any Gassaver hydrogen tinkerers tried this?

How would you convert the brake energy to electricity? 5th wheel that drags when the brakes are applied driving a generator/motor?
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Old 05-08-2007, 12:38 PM   #3
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How would you convert the brake energy to electricity? 5th wheel that drags when the brakes are applied driving a generator/motor?
Sounds like a regenerative brake solution to me. Instead of hydrogen, maybe this is an "ultracaps" oppurtunity that could take the recently created brake energy and feed it into a "mini-flat" hybrid electrical motor (that's what they look like to me), or maybe at least act as a "feeder" into the electrical system to give the alternator a rest.

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Old 05-08-2007, 12:51 PM   #4
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I was thinking the same thing; you would need a good sized motor to absorb the power from breaking. And if you have the motor why not use it for driving as well? And burning H2 in an ICE is what 20% efficient? I am not sure about the efficiency of making the H2 from electrical energy in the first place, maybe 30%? While a motor (which you would have either way) and batteries should be in the 70% range?

Or instead of batteries maybe use a capacitor? They can accept charge much faster then any other battery technology, and give up their charge faster as well. And like you said just grabbing the breaking energy and pushing it back out wouldn't be a huge amount.

I know it’s crazy but what about a spring for braking and then reverse that on accelerating? It seems like the simplest way to grab the energy?
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Old 05-08-2007, 01:28 PM   #5
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How would you convert the brake energy to electricity? 5th wheel that drags when the brakes are applied driving a generator/motor?
The alternator makes the electricity used in the hydrolysis, when the vehicle is IN GEAR and BRAKING.
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Old 05-08-2007, 01:38 PM   #6
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I was thinking the same thing; you would need a good sized motor to absorb the power from breaking. And if you have the motor why not use it for driving as well? And burning H2 in an ICE is what 20% efficient? I am not sure about the efficiency of making the H2 from electrical energy in the first place, maybe 30%? While a motor (which you would have either way) and batteries should be in the 70% range?

Or instead of batteries maybe use a capacitor? They can accept charge much faster then any other battery technology, and give up their charge faster as well. And like you said just grabbing the breaking energy and pushing it back out wouldn't be a huge amount.

I know it?s crazy but what about a spring for braking and then reverse that on accelerating? It seems like the simplest way to grab the energy?
1) Readily available 140 amp alternators are capable of putting out about 2 kw (3 horsepower) worth of electricity to make the hydrogen.

2) The point is that you don't need expensive batteries, ultracapacitors or a separate electric motor with hydrogen regenerative braking. You simply make hydrogen when braking, then use as fuel it when you drive away.

Lots of folks are working on ways to store braking energy. Ford tried hydraulic acccumulators, others have suggested compressed air and flywheels. Most of these devices are simply too heavy and costly to be practical.
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Old 05-08-2007, 01:57 PM   #7
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Right I understand the alt can put out 140 amps, well larger ones can, and typically they are in the 80-90 peak range, sometimes even smaller. But even at full load 3 hp’s is not much drag or braking power for a car. I bet you use 100 hp in a typical braking, maybe not the way we drive but most commuters, so 3 hp won't slow you much.

As far as cost a system for generating, storing and then re-injecting the H2 would seem to be pretty pricy to me. Again if you could use that 3 HP to make H2 and then burned that same H2 right in the ICE you might recover 1/2 hp when all is said and done.

I know it's more costly, but a motor/genset in place of the alternator would allow you catch that same 3 HP and get maybe 2 of that HP back, even using a smaller sized regular car battery for temporary electric storage. Also that 2 hp would be on top of what ever the ICE is making and reducing the load from the alt as well. So you might gain a full 3 hp back?

If you were to make H2 while idling or steady state driving the losses creating it would far outweigh the gains from re-burning the H2. Again say you’re idling and your engine has to create and additional 3hp, then get 1/2 hp back. Again I don't see how it could be to your advantage?

I am not knocking the idea, thinking out of the box is how most of us got to where we are now and we should continue to do it. But the little I know of creating H2 and the losses involved are extremely high, again much more so then just about any other storage medium.
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Old 05-08-2007, 02:01 PM   #8
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The alternator makes the electricity used in the hydrolysis, when the vehicle is IN GEAR and BRAKING.
Correct me if I am wrong (98% chance usually):

You are talking about a system where when the brakes are applied (and only then) that the cars alternator output is used to generate hydrogen??

If so, this isn't really capturing any braking energy, it is just taking advantage of the engine that is going idle during braking...perhaps even putting a larger load (causing higher idle) during braking. True??

I can easily see where if you could use something that would "drag" and turn some of the forward momentum of the vehicle into electricity (5th wheel suggestion) that simply piping the generated hydrogen back to be burned during accelleration would be a relatively cheap substitute for some gasoline. Seems like a good idea, personally. Only real hurdles I can see with that approach are:

1) Drag/generator system and integration with vehicles current braking system (maybe as simple as just sensing that the brake lights are on?)
2) Storage container for the generated hydrogen (think safety or at least anti-Hindenburg)
3) Calibration of the fuel system (if needed) for the addition of the hydrogen
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