help on hydro generation efficiency

The efficiency will depend on the equipment and the way you are going to use it but I would say a rough guess would be 85%plus.

I would imagine that you may use the hydro power to assist in peak demand periods. This may mean a Pelton @ 50kW.

The best would be to obtain specifications from the suppliers for your specific requirements.

As an alternative you can always export the surplus water to SA.

The shaft power of any fluid mover remainsas follows: the change in pressure times the volumetric flowrate, all expressed in compatible units, times the efficiency.

Hello Ted

This is Codey, not logged in.

According to my calc, power in the water is 0.84 hp, so you won't get much over 0.5 hp shaft power from your machine. Is it worth the trouble?

Codey,

You are absolutely correct:

The maximum available power (P) = Q * g * h

where Q : water flow ( 0.957 lb/sec), g = gravitation acceleration, h = height of water fall (400 ft).

Using compatible measuring units, the available power would be 518 W (0.7 HP), that is considering no losses at all.

The generator efficiency is high, even at this low power rating ( > 85%), but you have also to consider the turbine efficiency.

Check out Home Power magazine - http://www.homepower.com/home/ - they have some good articles on micro-hydro installations that should help.

Yes, Homepower is a good site. Also, if you google microhydropower there are a number of sites available that will step you through the calculations for several alternative turbine types.

I am CoronaCameraMan -

Your stated flow rate for hydro potential is about 0.12 cfs.

The run-of-river flow rate usually is very low in early months of the year, then about the end of March the flow goes to flood until May, sometimes very low by the end of May, then back up for a couple weeks in June due to rains, then drops off thru August, and in September thru October into early November flow is usually OK until freeze-up in late November and flow drops thru December.

So you have 0.12 cfs at some temperature/density at some point on that variable flow rate ? or you have a constant flow rate ? or ?

If at the peak the flow rate is 0.12 cfs at 400 ft of head (measured from the top of the water upstream to the top of the water downstream at the tailrace ?) then yes for that head and flow a micro-pelton turbine is best. The flow rate will determine the economics, is there a payback ? Local electric rates (either displace power or sell to grid) cost of a substation and relaying and distance to grid from hydro site.

Normally continuous flow must be maintained, but if you could "pond" or "peak", i.e. store all water and then only run the hydro at the peak electric rate normally during the day. If you could change to storing all the water and only run the turbine for 8 hours you would have 0.35 cfs at 400 ft head, if the peak electric rate is only 4 hours long then 0.69 cfs at 400 ft head, but what does your flow duration curve look like, how large is the head-pond ? how much will the tailwater rise at the higher rate (probably not significant, but may be objectionable) and would it create a downstream problem, can you stop the flow in the stream ?

Another consideration is the civil works to install dam and penstock, hydro plant and turbine-generator equipment and controls. If there is any cold weather, it brings in a whole 'nother set of problems and construction challenges to make it work year-round.

What has stopped many hydro sites is the esthetics, fish, water quality, etc.

I did start up a small hydro on the out-fall of a waste water treatment plant (20 MGD or 231 cfs at 70F at maximum 40ft head/min 30 ft head and about a 70kW actual best output), the water temp and some aeration in the water decreased the density and output power along with the minimum range of the head being greater then expected.

I think you can see where this is going, it costs as much to engineer a 50 W hydro as it does a 1MW hydro or a 10 MW hydro, but the bigger units have a payback.

Thanks for all the replies. Lots of good stuff, especially corona camaraman. No need for more posts.

Ted

Unfortunately, the flow rate is very low for power generation. My calculation indicate about 12 KWH MAXIMUM per day is available, using high efficiencies for the driver and generator. This is a nominal 1 HP Pelton Wheel driving a 600 w alternator. Almost any automotive alternator (15VDC) would be suitable to charge batteries and an inverter would provide 60 Hz A/C 120 v as needed. If you could keep the cost very low (<$1000), it would make a modest economic return ($2.40/day gross revenue @$0.20/KWh) Not much, but day after day after day after day.

My Friend,

The efficiency of the mini hydro power is not just taking the headrace from souirce to turbine... there are many things to consider before you will go the "efficiency".

Take notes:

1. Considering the headrace of your penstock after the surge tank is about 120M @ 140cms (cubic meter per second). Losses is about 30%. Then, you will have at least 50kW. Through my calcs the efficiency of the turbine generatoir would 85%.

2. Consider also the following:

* the weir or dam

* Surge tank (capacity)

* Penstock (piping)

* Turbine generator - (Powerhouse)

* Tailrace (Discharge)

All of the above should be carefully calculated before knowing the best efficiancy of the power plant.

Eren