Power generation using the potential energy stored in our tanks?

[Blom]

I am in the process of trying to design my next tank/fish room. Me and autocad have been fighting each other over possible layouts and what not. Trouble is I have no idea on the room I will have to do this as I still have to find and purchase a house. So I have decided to lay off the whole design for now until I have more info on the house. That being said I have found a whole new topic to waste free time on. This topic was poised by a friend of mine. He thought it would be a neat idea to try and see if you could design a tank to be as energy conciseness as possible. His idea was to try and use a combination of solar and potential energy stored in the tank to power the entire setup.

I thought this to be an interesting topic so we talked a bunch about it. Overall the end issue becomes cost. In addition to the cost of the tank setup which we all know to be costly, the added costs of turning the input energy needed to 0 is more than I would like to fork out. I did not do a cost benefit analysis to get a rough idea in savings in cost as it just becomes to complicated for a free time project (I have many projects for marks in school right now). That being said it did peak my interest in using it as a battery backup.

Idea:
Use small turbines to produce electricity to be stored in batteries until needed (blackout)

Concept:
A fish tank is just a box of potential energy, this energy is released as the water falls down the standpipes in the overflow to the sump/fuge or whatever. Mini scale hydro electric damn.

Initial reading:

My thermodynamic's textbook

DIY website http://www.builditsolar.com/Projects/Hydro/hydro.htm

And http://homepower.com/basics/hydro/

Ive got alot more reading to do before I have any loose numbers, but I thought i would get the topic going. Maybe someone else has done/thought about this.

[Delphinus]

Well, it's an interesting idea and I admit to thinking about stuff like this myself once in a while. But the problem is I'm a huge stick in the mud on most ideas. :lol: Here's what I don't like about the idea. :p

A hydroelectric dam is a hugely prosperous idea because Mother Nature (aka "Magic" :lol:) puts that enormous amount of potential energy up high for us, and we can then parasitically reap the benefit of the falling water and make electrons move around.

In the case of the aquarium, you have a pump lifting that water before it has a chance to fall back down. So you're providing the energy for the energy generation anyhow, and it seems to me it's probably less efficient than just plugging in a battery charger into the wall. Those turbines are going to put backpressure on the overflow piping as well which causes the water level to be higher in the main display and cause a flooding risk if anything gets in there (small fish, snails, etc.)

It's sort of like putting solar panels under your halides. Sure, it'll generate you some electricity back but you're casting a shadow into the tank. If you could put panels above the lights and catch the light that's lost upwards then you could probably recapture some energy but it's going to be a tiny fraction of anything that again I question that it's isn't just more effective to just plug the charger into the wall, or a solar panel outside would serve you so much better because then you're capturing energy that's there for free without you spending $$$ to power the pumps or lights in the first place.

[Blom]

Tony you are completely right, there is nothing "green" about this. The initial conversation between my friend and I was to do with trying to take the tank "off the grid" so to speak. The idea was an initial solar input feeding the system. Energy would be used to pump the water to the tank, and partially recaptured for use again using the turbines. there were some other additions is there as well, but like I said it was a little to ambitious for me for this upcoming tank. But it did get me thinking more about it than I care to admit. This would be more for a project of interest than any real environmental gains. But as I find it interesting it could turn into more of an experiment for a future design on a "green" system. Truthfully though... I just find it more interesting then my current design project in school. Procrastination :twised:

[Delphinus]

Hahaha, I hear you.

Honestly, I love the idea of an off the grid reef tank. To me though, I think approach would be about using the most low-footprint devices for one, minimizing consumption, and then using power generated from some means outside of the electrical utility. So, solar panels on the roof, a windmill, and geothermal, and so on.

[mike31154]

I'm slowly gathering the parts to generate some of my own power. Have a small wind generator & plan on getting some solar panels. Plenty of sun here in the Okanagan in the summer, wind is unreliable, so hoping a hybrid wind/solar system will at least provide enough juice to run some of my tank related gear. With LED technology now to the point where we can use them to replace power hungry MH & Fluorescent lights, it's going to make it a little easier to cut down on the total power consumed by our tanks. What's been holding me up is the up front cost of solar panels, batteries, charge controllers, wiring etc to get such a system up & running. The fact that power in BC is mostly generated by hydro dams & still relatively cheap, makes it more difficult to get a return on investment on the equipment needed to get off the grid. I'm sure that will change as they inevitably continue to crank up rates.

One good thing on the horizon IMO is the switch to smart meters. It's a controversial subject at the moment with a good deal of opposition from folks who believe the signal produced by the meters is harmful and that big brother is trying to monitor what we do in our homes. It's not a concern for me. With all the other technology out there today transmitting radio signals, smart meters are a drop in the bucket in that regard. The smart meter will however, make it much easier for those who produce their own power through wind/solar/micro hydro to feed the excess back to the grid, thereby saving money. Small grid tie inverters have come down in price significantly and the technology has matured to the point where you don't need to hire an electrician & pull a permit to install the wiring to feed the grid. They're now pretty much plug & play. Take the input from your charge controller or battery bank - feed it to the inverter - the inverter plugs directly into any wall receptacle in your house - done. The inverter automatically synchronizes the power produced by your home to match grid phase & frequency. It will also shut down automatically if there's a grid outage, preventing power produced by your home system from feeding into the grid while repairs are carried out to restore power.

As far as trying to recoup a few watts from tiny turbines running off your return plumbing, not really feasible or cost effective at all. Delphinus has already hit on some of the issues & pitfalls with that approach. I've done a bit of work helping out the owner of Boulder Hut with is micro hydro generator the past two years. We just installed a new generator which has the potential of more than tripling the current provided by the original one. But we're talking a system with a significant amount of head pressure and a 2 inch supply pipe fed by a creek not far from the hut. I think the water source is about 90 feet above the generator shack, providing around 35 psi of head pressure to spin the generator pelton wheel. If you start comparing the Boulder Hut scenario to an 11 or 12 foot elevation difference for someone with a basement sump, you don't even need to do the math to realize you're not about to get much in the way of hydro power out of that. You'll be better off designing your return to feed a skimmer directly instead of using extra pumps. This way you're at least recouping some of the work your return pump is doing.

On a slightly different tangent, while researching hydro power etc, I stumbled upon something that may actually be feasible in recouping some energy from a tank return, especially a noisy one that draws some air. Do a search on the net for 'trompe' and you'll see what I'm getting at. A trompe is a way of capturing/accumulating the air drawn down with a column of water in a chamber & then using that air pressure to run air powered equipment. One of the largest versions of this is/was used at a mine in Ontario somewhere. Again, not sure whether a marine tank return could produce sufficient pressure for anything, but I'm going to do a little more research into this. Might be able to at least run an air stone for my skimmer.

FYI, here's a photo of the hydro generator at the Boulder Hut. We were unable to run it at full power since the discharge water was overfilling the storm drain box the generator is mounted on, interfering/stalling out the pelton wheel. You can see the feed valve is only about half open. At this setting we were able to get 10 amps charge current to the battery bank. The best Mark could get out of the old generator was about 3 - 4 amps. Once he gets a large enough drain pipe to handle the discharge water volume, this baby is really going to hum.

https://blu1.storage.live.com/items/A0157E1B64909474!1114:Scaled1024/P1040504e2.jpg?psid=1&ck=0&ex=720

[Delphinus]

Neat!

Sorry dumb question maybe but what is the Boulder Hut? Oops, never mind, googled it. :lol: ... Neat!

[SeaHorse_Fanatic]

My friend's son is an electronic's expert who teaches people how to DIY their own 64 watt solar panels. I'm either going to have him build me a few or teach me how to do it myself if I have the time. Then I'm going to probably install a bunch on my flat rooftop leading to a bank of batteries in my front area which will then power my tank off-grid. I will have another set of panels on my pergola roof to power my new greenhouse (12' x 8' x 10' tall) once I build it, to power the koi pond pumps/filters/heater and lights/fans.

I figure the payback time for all these panels will be years, but its more of a cool project than a way to actually save money.

These are my plans but hopefully things will come to fruition this spring/summer.

Anthony

[MarkoD]

Hook up stationary bike to a generator.you get a workout while saving on power

[Lampshade]

The problem with doing a generator on the tank is the very small amount of pressure you get from the free fall of 6' of head pressure even at 3000gph is only 54W of power even with 100% efficiency(you'll probably have 50%). To save it in batteries would be a good idea, but you'd have to look at the cost per watt of the energy and see if it's really better than just sucking from the grid to recharge batteries.
http://www.fancygaphtrn.com/calculators/hydro-power-calculator

The easier way to cheat the system especially if you're on un-metered water is to just use your water line to your house :P. 80psi = 185' of head pressure. It would produce anytime you use water, and in a power outage, you could dump a little down the drain, haha. The solar idea would work, it's getting very cheap now to produce solar power and even in cloudy/rainy BC with some of the cheapest energy costs in the world it's becoming feasible to do it.

[FitoPharmer]

I thought these type of Stirling engine energy recovery systems were neat for saving some money. Just have to figure out if you can use them for a reef tank. Maybe run water cooled halide shades then run it through one of these :D

http://www.greenoptimistic.com/2010/11/09/evita-boiler-stirling-engine/

There are even versions that can take the energy left over from hot showers, dish washing, laundery, ect....

[mark]

A zero cost display is like perpetual motion, good luck, other than maybe go coral farming or fish raising to try to break even through sales.

[asylumdown]

I totally agree on the overflow recoup not being feasible, unless of course your system was gigantic. Cool idea though, it's like regenerative breaking on a hybrid car.

One thing I've heard of people doing to make their tanks more 'green' is to reuse the waste heat in other areas of the home. The one tank I saw this done on was like 1200 gallons or something ridiculous, and it was powered by umpteen million 400 watt MHs. The guy who built it lived in Minnesota or somewhere with horrible winters like that, so he built his house's HVAC system around the tank. In the winter exhaust heat from the lights would be used to heat the air in his forced air system, offsetting the heating bill for his house. In the summer when it wasn't needed, he'd just switch it so the tank exhaust would vent outside.