Backyard Aquaponics
A place to discuss aquaponics

Hi Everyone,

I have been watching this forum for a while and have eventually got around to signing up. Excellent information.

I am keen as mustard to get started on a system, have got the site picked, know what size tanks etc and the picture in my head is as clear as a bell.

However, I travel a bit for work and don't want to be away when the Murhpy's Law power failure kicks in and wipes out all my hard work.

So as an old bloke once told me, think about it 10 times and do it once. I am planning the backup power system.

I have considered solar, wind and I am now working on hydro. My thinking is that I have to pump the water through the system, so why not include a water wheel in the system somewhere to provide some power to charge the batteries.

Came across this site: http://www.ecoinnovation.co.nz/product_detail.php?id=1

Would appreciate any comments or thoughts, any issues or problems people can forsee.

I want a standalone system, i.e. batteries to inverter to pumps and air stone, with either solar, wind or hydro to recharge the batteries. Have got mains but don't want to use it.

I am not an electrician, so I may be wildly off track, any and all comments accepted.

Stick with mains power and battery back up air pump as for hydro power unless you have a flowing stream you will have to use $10 worth of power to get a dollars worth these things are not very efficient

You don't want to use mains at all, or just not to charge your backup batteries?
If it's just to charge the batteries:
The amount of power to keep the backup batteries charged up will be very small, and you'll spend heaps just setting it up.

Get a solar hot water system or solar panels if you want to spend money on something to reduce your total energy consumption. Or maybe a wind turbine...

Like f&f said, don't chase your tail by pumping water just to generate power.

I'm not sure I totally agree. It is easily possible to spend more on setting up a system like this than you will save, BUT...

Let's say you have a siphon drain from you GB to your FT. The power to pump the water up to the GB is supplied by the outlet in the wall. The power to siphon the water down is supplied by gravity. If you put a water wheel in the return flow, you'd add a bit more aeration and maybe a turbine shaft.

Of course, any such system would still have to be economical. I wouldn't dismiss it out of hand though.

Yep, I agree with that too Tamo I thought of it but decided it would be too confusing to give two opinions in one post
Re-reading, my post does sound very dismissive.

Well, so long as that's clear

Great to see comments so quickly.

I agree that it is uneconomical to setup a system like this just to produce power But as Tamo42 has pointed out, the water is moving already.

I see the power production being a bonus to the fact that I am using power to pump water around the system already and I am not doing anything extra other than adding the hardware.

I spoke to an electrician once, who informed me that it is impossible to get out more power than it takes to generate it...he explained why, but it went over my head.

What I am trying to establish is would the hydro power unit be adequate to recharge the batteries used to power the pumps through the inverter. Or would the power drain be greater than the recharge and eventually run the batteries flat.

A solar panel would do the same job and the energy from the sun is free, but cloud, rain, miserable winter days etc all affect the power output, wind power generation suffers the same outages as solar, whereas we must move water 24/7 to keep the system working.

What your electrician was trying to explain to you was the 2nd law of thermodynamics, and it's true.

BUT! (there's always a but)

The cost-efficient way to produce power is to inefficiently convert free power into power you pay for. So sunlight into electricity via solar panels, gravity into electricy via hydro, atmospheric thermal energy (stored sunlight) into electricity via windmills, etc.

And it's true that various different capture schemes have outages. That why you need a diversified energy portfolio, but I'll get off my soapbox now

Neglected to answer Steems question.
I don't want to use mains power at all. No reason other than the challenge of setting it up and operating the system succesfully outside of the grid supply.

I did wonder when I read your first post if you where suggesting Perpetual Motion. That won't work. Now if the Murray flowed past Dubbo ....

As others say Solar/Wind is your friend if you want to avoid mains. There are number of threads on that, and people on the forum with solar at least, can't remember any wind systems though

Edit : Just on the water wheel. If it was an open thing like the old paddle boat most of the energy would be lost. Water bounces off as the wheel resists being turned if connected to a generator. Similarly if is was closed like a turbine it creates back pressure, reducing the flow out of your beds

OK. According to the rules??!!

Eventually the drain on the batteries to pump the water would outstrip the charging of the batteries by the water running a turbine of some sort.

Therefore it would need a secondary source of power generation, which doesn't draw on the supply, to make up for the difference.

So, if I had a water turbine being run by the water being pumped from a sump to the tank AND a small solar panel on the roof adding to the batteries at the same time, any downtime on the solar wouldn't be a major problem, and the extra 'free' energy from the solar would overcome the "rule" problem.

Someone hit me on the forehead if I am getting this wrong.

Next question....can you have two sources of power going into the one set of batteries....how is that done and if there is an excess (really sunny day or something) will it overcharge (blow up) the batteries.

What happens to the 'spare' power I did say I wasn't an electrician...didn't I.

Having had one of those small turbines [up at bright in the hill country you would need a fall of at least 15 ft to get a usefull amount of power ] just a standard water wheel would need a supply of a small creek or a 20 ft dia wheel if only using a small amount of water. As far as perpetual motion goes good luck

Lets look at energy flow.... Use use power from a battery bank into a 12 volt pump. Forget inverters for now, one of their downsides is they do lose power to convert DC-AC, but thats another story...

Lets look at loses
Battery---> 12V Pump Heat, friction, magnetic fields, cable loss etc.
Water from Pump to GB Pipe friction, gravity, head hight etc.
Water ---> Turbine Again: friction, heat, magnetic fields, cable loss etc.

When you take the pump efficiency, gravity and turbine efficiency into account, the output from the turbine will NOT equal the pump input. You maybe looking at 20% at a long shot... Don't make me calculate it...

However, if it can be done at max efficiency and cost effectiveness then I say DO IT! It will put some charge back into your batteries, the water is going down anyway, so why not capture some of its energy. Top the rest up with solar and wind.

What you need to do is work out the the most efficient way to pump the water and capture energy from the return. Then compare the cost with some good solar panels. It may be worth your time and effort to just stick with solar. But hey... if you've got the cash, time and know-how do it

I don't think anyone is suggesting that a water wheel would equal the power used to pump the water up.

For the second bit, a solar regulator/solar charger. I am not sure if they are different. Like this one from Jaycar or a range of them under the solar regulators tab at The 12V Shop

For the first bit, yes. Not sure if it would be as simple as using diodes to prevent the two sources feeding each other (like your solar spinning the wind gen like a fan ), probably electronic jiggery pokery again. But IMHO a turbine from small fall of water in an aquaponics system won't rate as a power source. But being proven wrong is the only way I'll learn