Head and electric generation

[KEG99]

I have a client who is looking at a hydro project and the generation of electricity. We are doing a preliminary evaluation of various sites that also provide various amounts of head (elevation difference between top of pool and dsicharge into the generators turbines). I need to calculate the amount of generation we can expect for a given amount of head. Is there any guidance the group can give me to do some preliminary calcs? I'll be working details later, but need to get some rough numbers to help narrow down our site selection.

Thanks,
KEG99

 

[rbulsara]

I am no hydroelectric power expert. But Coversion of power is not that difficult, if you know the overall efficiency of the conversion setup.

See below:

http://www.wvic.com/hydro-works.htm

 

[tinfoil]

The two basic facts you need are:
1) The amount of water that will be expected to accumulate in the headpond (i.e. the new lake that your dam will create). Ideally, you should have data for min/max, or typical flows on a seasonal basis, as the flow of water in your waterway will be directly affected by the rainfall (or dramaticaly affected in spring by the melting of accumulated snowfall)

2) the typical amounts of head that you can expect as a result of (1) above. The amount of head is a function of the amount of water you are using to generate and the amount of new water you have arriving at the headpond.

Once you have this worked out (and it can be very complex, as the area you are flooding generally increases with head height, so that each extra meter of water in the reservoir represents a larger volume of water that the meter before.

You will likely also have to deal with lots of levels of government to adress issues with water levels and flood control!

However, once you have all of this worked out, the amount of power you CAN generate for a given volume of water is a fairly straightforward:
E(potential)=M*g*H
where M is mass of water, g is acceleration due to gravity, H is height of water
E(generated)=E(potential)*efficiency of generation, where the efficiency is itself a function of height.

The efficiency equation is very installation-dependant, but I have heard of conversion efficiencies form 50-90%, depending on scaler and design.

Edit: I went googling for a better efficiency value, and came across the following, which might be useful:

http://www.wvu.edu/~exten/infores/pubs/ageng/epp13.pdf

HTH