Designing a Hydro Generator for my Farm

[drewk79]

Over the past few years I have like many of you become interested in renewable energy.

Over the past few months we have gotten a lot of rain.

We also have a small creek in our pasture and it begins with 2-12 inch field tiles. The end (beginning i guess) has been filling with silt over the past 20 years and has now reached the top of the retaining wall so we need to build a new one a few feet taller.

I am thinking why we are down there working it may be a perfect opportunity to set up a small hydro generator.

I can weld and build basically anything ( I am a home builder) and my brother is a commercial electrician so I think we have the know how. I am just looking for some engineering and design help/suggestions.

OK so while I was down there the other day the 2-12 inch tile were running at what seemed to be full capacity. Maybe 60% full I would think that would be about 1 gal per sec per tile. If anyone has any opinions on that I am guestimating.

It is probably running 20%-30% higher than avg right now. Water weighs about 8 lbs per gallon. So ... I think i can reasonably get to 10 lbs a second avg. And it falls about 1 ft initially out of the tile. We have nice concrete walls on 3 sides and a concrete floor for about 10 ft. I will be adding a illustration soon.

OK I have done some more research and found I have 2-12 inch tile and they can flow 2 cubic ft per sec each. I think avg is probably 1/4 of that. appx 60 lbs per cubic ft. So avg work done is 30lbs drops 1 ft per sec on avg.

30 x 60sec = 1800 lbs 1 ft per minute

550 ft lbs a min = 1 hp

So i have a little over 3 hp

750 watts per hp x 3 = 2250 watts

2250 x 24 hrs a day= 54kWh

Any comments on these assumptions would be great.

Thanks

 

[russ_watters]

You're so close to having figured it out yourself (maybe you have, but you put ? in there...). Power is in foot-lb/min and you have information in units of feet, lb, and min. Put them together!

If I'm understanding you correctly, you only have a 1 foot drop to work with? anyway, potential energy is simply weight times height and power is flow rate times height. So if you have 60 lb/min dropping 1 foot, you have 60 ft-lb/min of energy at your disposal. That is about 1/10th hp, or 70 watts.

1 ft of drop seems awfully small, but if that's what it is, ok. Flow rate is pretty easy to find, though, if your water source is coherent: find yourself a 5 gal bucket, direct the water flow into it and measure how long it takes to fill it.

 

[drewk79]

So 2 minutes of research made me redo my assumptions.

As far as the 1 ft of work that is about how far the tile are from the concrete floor. maybe 18 inches but its under water so its hard to see and remember from yesterday.

I did edit my first post so if you could reread it with the new assumptions and let me know what you think so far

 

[Danger]

Amateur hour again... I don't really know anything about the subject. I am wondering, however, if you could dig the receiving basin a couple of feet deeper to gain more gravitational assistance from the falling water.

 

[drewk79]

Amateur hour again... I don't really know anything about the subject. I am wondering, however, if you could dig the receiving basin a couple of feet deeper to gain more gravitational assistance from the falling water.

Are you calling me an amateur? I know I am. But I am trying to learn and I find this site very helpful. Should I just keep my comments to myself or...

If you were talking about yourself being an amateur I enjoy all points of view.

I have found a micro hydro calculator and I according to it 100 kWh a month are possible in the wetter months. Also since I am at the beginning of the creek I have a perfect opportunity to harness this energy for a very low initial cost.

So far I am imagining a 6 ft radius water wheel a pulley and shaft up to dry land. At that point I could have a mounting plate for 3 generators (or one big one) They could be connected and disconnected very easily.

100 kWh is about the entire farm monthly use. So maybe just a 2-3 year return on investment.

 

[Astronuc]

Here's a tutorial on water turbines:

http://mysite.du.edu/~jcalvert/tech/fluids/turbine.htm

This provides a simple overview
http://en.wikipedia.org/wiki/Water_turbine#Typical_range_of_heads

There is actually a special design for low flow, low head situations but I can't remember the name at the moment.

 

[drewk79]

Thank you I had not thought about wiki

I went to the creek again this morning. I was expecting some rain according to the radar but nothing and I am trying to decide how tall to make the new dam for overflow water.

The tiles though where in fact still flowing I would say 80% max. So I think it will be easy to take another piece of 12 in tile and build a small model in the garage and then simply side it into place once completed.

I will keep you updated.

 

[Danger]

If you were talking about yourself being an amateur

That is indeed the case; I hoped that you would understand that.

 

[drewk79]

That is indeed the case; I hoped that you would understand that.

I feel pretty intelligent when I talk to friends and peers but I get a bit intimidated on when I put some ideas out there for others to see.

In reference to the generator I have found there is a small dam about 100 yards doinw the creek. I can lower the water by removing it. This will get me to about 3 ft of head.

Also I have found water wheels are not easily adapted to electric generation so I am looking at a kaplan style turbine.