Microhydro in GA - low head, high flow, low velocity

Hi,

I've been doing research on microhydro, but I'm having trouble finding expertise to evaluate the stream on my property. I live in NE Georgia (not at the foot of the Appalachian Hills, but a little further west). The stream section I have is ~1600' in length, and I have not calculated the head yet, but my best guess is 15' from beginning to end of stream (my father will be using his surveying expertise to calculate this for me). The greatest width is 17' across, the least width is 10' across, the max depth is 4'10", min depth is 18" (at the broadest point going over rocks). I've included a picture so you get an idea of what it looks like at the bend. Granted this was after a rain, but after the rain runoff, it goes down ~2.5'. I'm looking for someone to tell me which turbine would be best for this situation, an estimate on how much energy I can obtain (to see if I can go off the grid), and how much it will cost to do it. I have seen various calculators for how much energy can be obtained, and various dealers, but none in my area, at least that I can find. Can someone here point me to someone in GA who might be able to help me, that won't cost me an arm and a leg?

Thanks,
Tracey

Wonderful! That is awesome...

Go measure the head. if it really is 15 feet, you are the winner of the day. If it is 15 inches, it becomes an instream paddle wheel.

The amount of head makes a huge difference.

You MIGHT get away with a turgo for medium heads, but that would involve a lot of expensive piping. I have a 6 foot head and an axial turbine making anywhere from 200 to 450 watts an hour, 24 hours a day (thats more than you can use, I bet). See http://www.youtube.com/watch?v=4teOp0YYmwY

As previous poster noted, head is all-important, as well as flow. Easy to figure enough with a gps. Also easy without a gps if you have some time, a level and a measuring tape.

Measuring Head
Head is most easily measured using a hand level or "pea-shooter". This work is done with another person. The person using the level stands at the low point, where the turbine would be and directs the other person (siting person) to walk uphill until they can see their feet when siting level. The level person walks to where the siting person is standing and the process is repeated. The number of times this process is repeated is counted. That number is multiplied by the height between the ground and the level person's eye when standing straight. While measuring head with a level, a 200' tape can be used to measure the horizontal distance needed for the head drop.

OR:

http://energy.gov/energysaver/articles/planning-microhydropower-system

Then figure flow at low water:

same web page as above, or google it. Pretty easy.

When you have that, use an online calculator:

http://www.baipatra.ws/hydropower_cal.html

or a lot of others. Figure half of that number will be what you get consistently. As for cost, I spent probably over $30,000 on mine over 13 years. Figure $1500 or more electricity bills a year time 13 = $20k+/-, and you have an idea. You can go cheaper, but it aint worth it. I built the whole thing myself mostly, but bought good equipment. Batteries alone will be a large part of the cost. But never forget this: THE most important part will be the screening. If you screen it properly, you will love your machine. If you don't, or cut corners, you will hate it forever. I can't fix my bad screening without huge cost and effort, so just live with the consequences, and now use solar for main power source, and hydro for backup and power tools/vacuuming, laundry, cappuccino maker, microwave, etc. Much easier that way.

Jeffe

Site assessment:

My book, Microhydro: Clean Power from Water, has a long detailed section on surveying your site for water power potential, including estimating water flows.

It's available from New Society Publishers at newsociety.com.

Or, here's link to a booklet I helped to create, the Natural Resources Canada Microhydropower Buyer's Guide:

http://canmetenergy.nrcan.gc.ca/renewables/publications/2427

It has good information also.

Cheers,

Scotty

Scott is definitely the man to speak to, or to listen to, about micro-hydro, for sure!

This could be a good site for a vortex micro hydro system like this one:
http://blog.hasslberger.com/2007/06/water_vortex_drives_power_plan.html

That's a plant generating just under 6 KW with a head of a little over 5 ft.

Would be better to have some flow and head data on this vortex site for comparisons... thanks!

That's not too difficult just based on observation.
The vortex chamber is 5 m diameter and looking at the proportions of the design, the intake channel is about 1.5m. The height of the channel is the same as the vortex chamber, and compensating for 0.1m clearance, we get roughly 1.5m also.

So the inlet channel is 2.25 sq meters.
Looking at the videos of this in operation, it looks like the water flowing is flowing at about 0.5m / sec. This equates to a flow of about 1 cubic meter per second.

Actually, here is an interview with the designer. He actually gives the dimensions, flow rates and head data you are asking about:
http://pesn.com/Radio/Free_Energy_Now/recordings/2008/080310_FranzZotloterer_GravitationalVortexPlant.mp3

In this interview, he confirms my observations. He also states the theoretical output is around 12KW. The generator itself is generating between 7 and 10 KW continuously. That's enough to fully power a modern home during peak load time.

More details about this site:

It looks as if there is lots of water.

Many times, you design a system around the available turbines and this seems a good idea here. There are many low head turbines available, such as the Powerpal turbines at powerpal.com and Energy Systems and Design at microhydropower.com. You do seem to have enough water that five or ten feet of head should deliver all the power needed. Serious Microhydro: Water Power Solutions from the Experts, features case studies systems with heads down to 22 inches, and many in the 5-10 foot range.

Every site has advantages and disadvantages. This site seems very flat, with only a drop of a foot or so per hundred feet of run. Many times it is more practical to consider ease of construction over maximizing power output. In an off grid situation, a system that is twice as big might easily cost twice as much, but may not deliver twice as much service. So, using only part of the head available might allow you to site the intake at a convenient spot.

It's all too easy to have the part of the system that gets the water to the turbine, whether its a ditch, flume or pipe, to cost way more and be way more trouble than the turbine. Reducing these costs is an advantage of the low head turbine, if there is plenty of water available.

Getting the water out of the stream and into a pipe or ditch may be the major challenge here. Intakes are discussed in my books and in the Microhydropower Buyer's Guide, but you can also look around and see what other people have done in your area. People have been getting water out of streams and rivers since forever and there are many clever designs out there. Some might be nearby...

Cheers,

Scotty