Backyard Aquaponics
A place to discuss aquaponics

G asked me about whether a site was suitable for hydro power the other day.

Well a site I looked at yesterday is suitable.

The site is beautiful but not very flat. The top of a ridge has already been leveled for a 2000m2 greenhouse and there is more room to extend the flat area long the ridge to give maybe 1ha overall

There is NO power even anywhere close.

However there is quite a fall though from the ridge to the creek.

I'm not sure how much but based off the contour maps I have its at least 50m maybe 70m.

Back of the envelope costing for a hydro system:

Header Tank ~1230m3 $25k
750m 200mm pipe $15k
Dam 3ML $5k (quote apparently)
Pump/generator ?
Cabling 750m cabling ?
Structural works $10k
Control System ?

Assume running the hydro generator for a max of 18hrs/day (Winter over cast) that is a flow of ~19L/s. At a head of 50m that is a maximum generation capacity of 9.3kW. Running 18hrs per day that is ~160kWh.

What would be the overall system efficiency?

Headloss through pipe line is only about 2m (2/50=.04) 96%
Generator ?
Voltage drop ?

Any informed guesses

You'll be doing very well to get 60-70% round trip efficiency. Sounds like it isn't very steep, which adds expense. I have 85m in about 250m here With 750m of cable, you'll want to do it at high voltage to minimise I^2R losses/volt drop. There are MPPT charge controllers around that are rated up to 600V input I think.

Black lines are the property borders.

Blue lines are the alternative pipe lines. The pipeline labelled no.1 is to the best cheapest, largest, dam site. By moving the tank to the internal corner of the property both pipe lines no. 1 and 2 are shortened to 500m.

The pipe line to the ridge to the NWN of the best dam site is obviously much shorter and is actually a greater fall than the potential GH edge. Power would obviously still have to go the other way.

The dam that is already there (pipe line 3) is not very big plus the fall is only about 20m or so.

Maximum acheivable head is top priority I think- the energy stored in the water is greater per unit volume, meaning a reduced flow rate is required for the power generation, saving on pipe size, dam size etc. Of course its going to be a compromise between that and cable length, access, etc.

The only thing I see about hydro power is a constant supply of water
A seasonal creek doesn't cut it and you are not allowed to dam a seasonal creek
And theres a lot of restrictions where you can put a dam now
That creek is in the can curren reservoir catchment area
Also the weather mob is predicting another elnino

With pumped stored hydro you are not using up water, you use the same water over and over. No need for a flowing river to supply it, as the only losses are through evaporation. You can float the solar array for powering the pumps over the lower reservoir to reduce evaporation via shading.

You would need a pretty good structure to do that though. Something that could handle the regular rise and fall of the water level.

Floating solar arrays are appearing all over the world. Cooler air over the water helps get a bit more output from the panels, and it can be handy when suitable land area is in short supply.

I'm aware of the technique it was more a concern over engineering the tethering and pontoon system to handle the frequent variations in water level.

I submitted a proposal to DISCUSS the potential of putting floating solar panels on an unused reservoir. The idea was to give me power for an AP system but also with the aim of assessing the reduction in evaporation and for phase two to locate a system on an irrigation reservoir (ie not used for town water) to power their pumps.

This is the response I got:

Here are a couple in the news recently:

http://www.energymatters.com.au/renewab ... sa-em4715/
http://www.energymatters.com.au/renewab ... il-em4750/

is one even allowed to simply dam a creek on private property in australia?

properties my uncle owned in the past he was lucky to even be allowed to go fishing in the creek legally.

or are you thinking of diverting to a tank to then release back to creek?

The water is contained in a header tank or dam at the bottom of the hill.

During the day using electricity from solar panels you pump to another dam or tank at the top of the hill.

Over night you release the water and run it through a hydro electric generator to produce electricity.

Power yield is W=Qghμ

W=watts
Q=Liters per second=L/s
g=gravity constant=9.81m/s^2
h=head hieght or fall of water=m
μ=efficiency

I agree with F&F on the statement "The only thing I see about hydro power is a constant supply of water".

As to your formulae (not that I could understand it) you have to build in a x R factor which is based on the number of things that could *frack* up; add that to the efficiency factor and a x T factor (as in how long it will work).

Unlike the words of the song, you do not get your money for nothing and your chicks for free.

Btw you appear to be going to build part of your greenhouse on your neighbors property.

I'd be paranoid that you'd need that water you're pumping back and forth for the farm.

Aren't there commercial batteries that'd be more efficient than pumping water back and forth? I know the tesla powerwall is doing a big commercial system, it seems something like that would be a better idea to me.

I haven't done the sums though.

It depends.

The life span of pumped hydro is pretty impressive compared to batteries.

There are many variables so you have to crunch the numbers to see if it stacks up or not.

I'm more familiar with hydro on a larger scale for utility load balancing. I didn't have it in my head to think about it for small scale until I had two people in a row remind me of it.