syphon well water for power generation

I don't have any pipe friction data with me here, but you need to check that when you lift the water the 25 feet to the top of the siphon, minus pipe resistance, you still have enough pressure to exceed the vapor pressure of water at whatever its temperature is.

The theoretical limit of lift is 34 feet. My rough guess is that 25 feet is borderline but feasible. To get your siphon started, you will need to get that much suction on the lower end of the hose. I would go for it--give it a try.

In theory yes but unfortunately reality is going to dictate that after all losses your likely going to have dismal power generation. Even with a 200 foot drop using 1 inch pipe, and assuming its less than 500 feet from well head to the 20' ASL point, you will only have at best around 50 PSI (probably less) at 5 GPM which works out to less than 100 watts of workable energy assuming reasonable efficiency losses.

The cost avoidance numbers on the pipe and related components will be decades long for what possible energy you may get back from it.

Depending on efficiency, I get about 100-150 watts for this, which may be useful for some small loads.

Friction loss in smooth plastic is 1.6 feet/100 in @5gpm and 0.4 feet/100 in 1.25 inch smooth plastic. You have not stated the total piping required but I suggest you put your suction end of your syphon pipe at least 40 feet or more into the well. More if you expect the static level to change. At present you have 25 feet of head to overcome at the well head (add friction head for pipe and all fittings). If you have 300 feet of 1 inch piping in total you will have to add at least 1.6 x 3 = 4.8 feet to the 25 feet or a subtotal 29.8 feet of head. You will have other loss for elbows, connections, etc. I don't think 1 inch pipe will work in practice. It is even borderline with 1.25 inch pipe. You will have at most 5 feet of drawdown to work with. It is very close but go for the larger pipe to reduce friction and make sure measurement is ID not OD. I do believe a practical syphon lift max on most situations is a total of 25 feet. It is very difficult to prime shallow lift pumps deeper than this level, I've been there and it can be done but ugh.

You can reduce friction head by placing the pump to the top of the well and use it like a normal centrifugal shallow lift or even use a deep well jet or better a submersible if possible. Power to the well head may be better option.

The water level is 140=25=115 feet below the well cap. There is no way a syphon can suck the water up 115 feet.

Hj Bioramani

I agree a syphon is not possible if water is 115 feet below the top of the well. It is standard to report all levels in a well as measured from the ground surface to the water level. OP reports water at 25 feet which is the static level ( the level from the ground surface to the water when the well is fully recovered). The fact that water was found at 140 feet does not mean that is the static level. Artesian pressure pushers it up to 25 feet as measured from the ground level If this is not the correct level OP should clarify.

OP says 'within the pipe it rises to about 25'. I interpreted that as 25' static head. If that is wrong you are right. We had a rather similar situation in Kerala in South India, where a perennial rain fed small pond was located about 150 feet above a field below. The quantity of water did not justify any large hydro electric generation. The small dia PVC pipe that was tried did not generate any power worth the effort of maintenance and the project was given up.

Hi Hiddenbasin

I totally agree with Bioramani that in your case syphoning well water with differential head of 115 ft, is not possible. Even though you have sufficient differential head to pull a vacuum at the well cap but the lowest vacuum is limited by the vapor pressure of water. Let say if your water well temperature is 30C, the vapor pressure is 0.615 psi (from steam table). This means that the maximum pressure differential available is (14.7 - 0.615) = 14 psi. If then I use the pressure drop as given by Kevinm of 1.6 psi per 100' that gives 2.24 psi for a 140 ft deep well. The remaining pressure differential then 11.76 psi or equivalent to 27 ft of water. Therefore the deepest well that for syphon can take place is 25 ft + 27 ft or 52 ft as compared to 140 ft in your case.

Hope the above gives some insights on why I said it is not possible.