Well the SI system (I don't know why we call it metric) has water weighing 1 gram per cubic cm (cc) and a liter happens to be 1000 cc therefore weighing a Kg.  See how easy it is!  Anyways something wierd is going on with the maths because these examples do not agree in the slightest.

Joe

Kirk McLoren wrote:
I never made the transition to metric. Still using furlongs per fortnite.  Anyway, 100gpm is about 800 pounds per minute(830 is closer but. . .) and 25 feet would be 800x25 or 20,000 foot pounds. A horsepower is 33,000 foot pounds/minute so you are looking at about 2/3 of a horsepower for 1 minute. In electrical terms a horsepower is about 750 (746) watts and 2/3 of that is 500 watts for 1 minute or 0.5/60 kwhr or 1/120 of a kilowatt hour.
 
Kirk

Joe Street <[EMAIL PROTECTED]> wrote:
Ok well according to them (your link)  they are indicating that from a similar height (25 ft) 100 GPM will result in 300 watts being generated.  My example released 400 gallons in 10 seconds and I calculated 160 watts.  But my example has 4 times as much water in one sixth the time so why do I not get 24 times as much power?? I must be overlooking something obvious here... I could have used the wrong formula but I checked it and it was the right equation....scroll down  http://www.answers.com/topic/watt  This is the basic definition of power i.e. force through distance over time.

What gives??

Joe



Zeke Yewdall wrote:
Take a look a the standard calculations for microhydro power systems.   You need quite a bit of water, with decent head, to get any power.  http://www.harrishydro.com/determineoutput.html      On 3/2/06, Joe Street <[EMAIL PROTECTED]> wrote:    
I was trying to do one of those back of envelope calculations but the  numbers I came up with are depressingly low. IIRC the formula for power  in watts is (Kg*m^2*s^-3) So for a sample calculation I considered the  following;  25mm of rain will fill my cistern which consists of 8, 50  gallon drums or roughly 1600 liters of water.  If I had placed the  cistern on stilts (strong ones) at roof level (roughly 10 m) I would  have 1600 Kg at 10 m head.  If I released all this water and it went  through a 100 % efficient turbine in 10 seconds I could generate 160  watts during that time according to the above formula.  Did I do  something really dumb here or is that realistic?    I feel like I missed something....I hope.    Joe    Evergreen Solutions wrote:        
7. In high school I had visions of a device for recharging batteries  that went something like this: captures rain in a funnelled system  (big opening = more
 rain), rain travels downhill turning a series of  wheels/cogs that via a system of gears works down to a very tight  ratio (one spin of the first wheel = ~10 of the smalll wheel) which  spin alternators to generate a charge to the batteries. The higher the  system starts aerially, the more primary wheels, the more kinetic  energy. Never built it, but...seemed reasonable. Then you could use  your captured rainwater for your crops/drinking/whatever.              
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