#143408 - 08/09/08 01:18 PM
Re: Pump Up, Drain Down
[Re: Raspy]
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Old Hand
Registered: 02/08/08
Posts: 924
Loc: Toledo Ohio
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I think for a small home application like any of us would have it would be better to have batteries and also install a wind generator or 2 of them to work at night when your solar is down.
Lots of plans on the net for homemade wind generators.
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#143438 - 08/09/08 09:31 PM
Re: Pump Up, Drain Down
[Re: BobS]
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Old Hand
Registered: 08/28/04
Posts: 835
Loc: Maple Grove, MN
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I just read that someone had a breakthrough in hydrogen/oxygen electrolysis, and that this combined with a fuel cell might be the way to go for storing energy for nighttime electrical power: http://web.mit.edu/newsoffice/2008/oxygen-0731.htmlOne thing that isn't mentioned in this is that another use might be filling up your hydrogen powered car with solar generated hydrogen.
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#143448 - 08/10/08 12:29 AM
Re: Pump Up, Drain Down
[Re: GoatRider]
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Old Hand
Registered: 03/24/06
Posts: 900
Loc: NW NJ
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Looks like it takes a MIT genius to re-discover electrolysis. C'mon, we all did this in high school chemistry!
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"Never trust and engineer who doesn't carry a pocketknife."
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#143449 - 08/10/08 12:35 AM
Re: Pump Up, Drain Down
[Re: nursemike]
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Old Hand
Registered: 03/24/06
Posts: 900
Loc: NW NJ
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The ram pump is useful if you need to a little water to a higher level by using a lot of water flowing down to a lower level than the source. There's no point in ram-pumping water up to a higher level to then run a turbine - just put the turbine where the ram would have been, lower than the source.
Martin mentioned in other threads that he has a pond on his property, but I assume it is only fed by rain and there's no spring or stream running into it. I don't know if there's any "downhill" for him to use, either.
_________________________
- Tom S.
"Never trust and engineer who doesn't carry a pocketknife."
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#143465 - 08/10/08 06:26 AM
Re: Pump Up, Drain Down
[Re: thseng]
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Enthusiast
Registered: 01/08/04
Posts: 351
Loc: Centre Hall Pa
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thseng The Idea is to put the ram pump at the output of the turbine not in place of it. It then pumps a portion that has already spun the turbine back up to the retention pond.You pump roughly 1/7 of the water back up.
Sure we did electrolysis in high school. But it took more energy to split the water than you could receive from then using the hydrogen as a fuel. What the professor is claiming is a breakthrough that people have been trying to do for quite a few years. The idea is to use a catalyst that requires less energy to split the water. With the right catalyst you can get out more energy out than you put in.
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#143495 - 08/10/08 04:22 PM
Re: Pump Up, Drain Down
[Re: Raspy]
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Pooh-Bah
Registered: 09/01/07
Posts: 2432
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There is a really good reason a pump up-drain down system isn't used: transition losses. I used to have the actual current figures but just operating off memry the water ram system required four gallons of water through to pump one gallon up even on a well adjusted system. Using electric power to run a pump is something like only 25% efficient at best. And getting electricity back out through a turbine only 40%. So for every 100 watts you put in your getting ten out. (100w x .25 x .40 = 10w) Your losing 90% off your energy just in transitions. Ancillary losses, evaporation, friction and heat loss in transport, are going to a bit more after that.
Of course if you have a huge, and essentially free, initial energy source of an intermittent nature and no other way of storing energy to use on off times then over 90% loss could be quite acceptable.
A simple battery system, 12v to charger and battery bank to 12v use or inverter for AC loads, can get you much higher efficiencies.
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#143566 - 08/11/08 01:44 AM
Re: Pump Up, Drain Down
[Re: Raspy]
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Old Hand
Registered: 08/28/04
Posts: 835
Loc: Maple Grove, MN
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With the right catalyst you can get out more energy out than you put in. Um, no, that would violate the second law of thermodynamics. But regular electrolysis is way inefficient, this makes it a lot more efficient.
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- Benton
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#143666 - 08/11/08 03:30 PM
Re: Pump Up, Drain Down
[Re: GoatRider]
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Old Hand
Registered: 03/24/06
Posts: 900
Loc: NW NJ
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Ok, this video actaully 'splains it a bit better than the press release that simply seems to be trying to cram in as many PC buzzwords as possible. It seems he thinks he's found a more economical material for one of the electrodes. Traditionally, platinum is used for both electrodes but it is naturally very expensive. He doesn't seem to be claiming any efficiency improvements over platinum. Anyway, drawing from the wind turbine thread, how about using a windmill to pump the water up?
_________________________
- Tom S.
"Never trust and engineer who doesn't carry a pocketknife."
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#143675 - 08/11/08 03:54 PM
Re: Pump Up, Drain Down
[Re: thseng]
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Pooh-Bah
Registered: 01/21/03
Posts: 2203
Loc: Bucks County PA
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Looks like it takes a MIT genius to re-discover electrolysis. C'mon, we all did this in high school chemistry! Better catalyst= less energy. That's all.
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#146236 - 08/27/08 09:12 PM
Re: Pump Up, Drain Down
[Re: CAP613]
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Pooh-Bah
Registered: 09/15/05
Posts: 2485
Loc: California
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I wonder if you could do something like this with compressed air ? I guess you can, at least on a large scale. See article here .
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