Renovating a small hydro-electric power plant

We acquired a non-functioning hydro-electric plant a few years ago. It was built in the early 1920's. The dam is a low 2 meters and long term river flow averaged over 500 cfs. Recently droughts have reduced river flow to 200 cfs. The Francis turbines were undersized, for unknown reasons. The two Westinghouse generators are rated 300 kWh at 150 rpm, but the two Leffel 36 Z type turbines (undersized during construction) could not bring them up to that speed. Power generation was abandoned long ago. All of this is the bad news. The good part is we have a power plant, dam, some old equipment with little wear and an interest to determine if and how power may be created here.

One strategy is to abandon one turbine/generator unit and degrade/rewind the operating generator so it can be driven by the 36 inch turbine to produce d/c power at variable stream flows. And then invert the generated d/c power to a/c. Does this seem optimal to the experts on this forum ? What could this cost and how much power can we create at 400 cfs?

The river is fairly wide and slow flowing - perhaps 1.5 to 2 fps. Is it possible to install a large diameter water wheel to provide torque to a wind generator mounted above the river ?

Thank you for any advice you can share,

Peter

Hello Peter,

Are the two turbines still in working order? If so it appears to an installation mishap that should be able to be corrected. That is of course if the head is of sufficient height. If not with that flow of water other systems are easily installed including gaining sufficient head for your Francis.

Peter

Peter, thank you for your reply. The turbines and generators were mismatched, wen the turbines were undersized. The head of our dam is also low - 2 meters. Although long term water flow is over 600 cfs, it has been reduced to around 200 cfs by drought conditions.

How can we increase the effective head and what is the associated loss in power or efficiency ?

Hello Peter,

Unfortunately I not have a lot of good news. Flow is not your problem head is. Francis turbine generate 720 watts for each litre of water at 9 bar pressure, one bar being 10 meters vertical water fall. a 2 meter fall will generate electricity and the volume per second is a plus.

Wattage being bar x volume per second. In your situation of reasonable volume but low head I suggest a micro Pelton.

However the cost of such may be greater than a CO2 turbine which self runs 24/7.

Peter

I do not quite understand - the head is marginal at best. What we do have is power generating equipment, a dam and power plant. It seems to me a starting point is to determine what can be generated here and at what cost. If the kinetic potential is 250 kWh, how much of that can be actualized by modifying the existing turbine and generator. And what would that modification cost. As an example, could we generate 200 kWh by rewind/degrade the generator and overhaul the turbine to generate dc power to avoid speed control/synchronization and then invert to functional ac power? If this could be achieved for $500,000, we would have a strategy to fall back on.

Also, I am not familiar with a CO turbine or system. Could you elaborate ?

Hello Peter,

Each and every turbine has a specific head and volume need. Six foot head at best, have you put the Francis into the flow, does it spin?

CO2 turbine are those which use Carbon Dioxide in place of steam as motivation force. thaw steam from ice to gas a heating of +100*C
is required. To thaw Carbon Dioxide from ice to gas a heating of -40*C is required.
The expansion rate of CO2 far exceeds that of water. Water at +100*C produces pressure of 1 bar. Carbon Dioxide at +100*C produces
pressure of 10,000 bar.
CO2 turbine are self cycling and without assistance. CO2 a natural refrigerant cold and proceeding to the boiler may pass through both a
freezer and a fridge on the way to further heating if required or the pressure the turbine needs for the given task.

Peter

The Frances turbines have been in the water since 1921 in this existing hydro-electric power plant and dam. The turbines were mismatched to the generators therefore the plant never operated properly. We are exploring re-building or modifying the existing equipment to generate power.

The perpetual machine you describe is interesting and may warrant a closer look in the future. Right now, we are concentrating on the assets we have on hand. We understand the limitation of a low head and the compromised turbine. However, technologies are available today to generate some power with what we have. My post seeks options for our equipment and we appreciate any input from this forum..

If the turbines have been sitting idle in water for almost 100 years then I would suspect the bearings etc are shot.

Technology has moved quite a ways since then as well. Not just with electron load balancing, but generator technology as well.

I would be inclined to strip out the turbines and generators, and sell them as scrap. I'd then use the money to purchase newer, lower rated generators and turbines. Personally, I'm surprised that they expected to generate 200KW with only a 2m head.

If you're seriously looking at sinking half a million into this, then I would hire a consultant to check out the site. It'll cost a few thousand, but they may save you much more in the long run. There is a good reason why the project was mothballed. Maybe finding out why would be a good exercise. If it was technical / economic then things may not have changed.

The Frances turbines have been in the water since 1921 in this existing hydro-electric power plant and dam. The turbines were mismatched to the generators therefore the plant never operated properly. We are exploring re-building or modifying the existing equipment to generate power.

The miss match of turbine and generator does match the parameters. All hydro turbine are calculated in flow litres per second and the bar pressure such occur at.

Turbines rated 82% efficient. A minimum flow of one litre per second at nine bar pressure produces seven hundred and twenty watts.

One bar of pressure is the vertical fall of water ten meters.

Volume however can replace pressure.

5,663 litres per second current conditions. 90 meter fall 720 watts = 8 watts per meter fall in one second, 2 meters 16 watts. Flow rate 5,633 per second 90,608 watts.

Francis turbine is rated 82% efficient however it have a minimum head need!

Turbines have a regulated flow and pressure, while the water goes up and down with modulating river flow.

Should the water level and flow rate no longer be that set for the system it become defunct

All turbine are rated by flow and head, a catalogue search of the web may be of assistance.

Peter

From your comments you appear to have a similar set up to these people.

http://www.hydroinsure.com/Hall%20of%20Fame.pdf

I would suggest getting in touch and visiting the site to see the potential of your equipment. They might even be able to assist in the refurbishment or at least point you in the direction of the contractors they use to repair and maintain the equipment.If you where in the UK I could point you in the direction of a turbine company who would refurbish your existing kit. They have even refurbished the hydro plant of the first UK house which had electric installed.

Is this the same site as in this thread

http://cr4.globalspec.com/thread/43688/Overhauling-a-small-hydro-electric-power-plant

If so what has happened to the site since 2009

Good afternoon Peter,

I am an investor interested in small hydro plant projects. We look for local, passionate operators (seemingly like you) to partner with. I read through this thread and would be interested in learning more. If you are open to chatting sometime, just let me know.

Regards,

Todd

Peter,
My partner and I each have over 30 yrs experience in hydro power rehabilitation, ownership, operation, investing. If you are still looking for assistance with your hydro site please let me know. Regards, Craig

well sir, i have been in the hydro trade for 30 years (hydrowest). turbines and generators were very expensive and the old timers were very smart; i sincerely doubt that they would have made such a big error in turbine selection at your plant. in my desk drawer is Leffel bulletin #54 from 1916; so, let me see---ah, here it is---for the 36Z, at 7 feet of head, you should make 112hp at 110.5 rpm while passing 173.67 cfs of water. so you are right, there is a mis-match between your turbines and generators at 7' of head. But: at 13' of head, the 36Z's make 294 hp at 150 rpm while passing 240cfs of water (a perfect match). i think your problem is that your dam used to have 6' high flash boards. replace the flashboards and everything will be correct. check the dam crest, a 6 pack of bridal veil pale ale says there is a pipe socket every 2 or 3 feet for the flashboards.

if the wicket gates were closed, i think you will be suprised by how little corrosion there will be on your Leffel runners. i have dealt with many old hydro plants and rust is usually not the problem you would expect it to be. you probably cannot run with your dc idea as the turbine runner is held up by a big Kingsbury bearing that is integral to the generator. replacing the kingsbury with something different is a great difficulty.

best regards, eric

Good day Peter McKinlay. You sound so knowledgeable in this area. I will like to have a word with you. Just joined this site and could not see how to reach you personally. I am working on a brand new idea and I believe your inputs will help us a great deal. Please advise me on how to reach you. Thanks. My email is waillus2000@yahoo.com

Hello Peter,

We have a lot in common. My 1898 dam is stone masonry, 10 feet high, 75 feet wide and HUGE flow. Have you looked into Ossburger turbines? What about dc power used to separate hydrogen out of water from the stream and use it as fuwl for an internal combustion engine running an ac generator? Maybe we can combine resources and time to evaluate the best hydro generation system for our sites. Most technology is for high head low flow.