Domani Aquaponics Ne Thailand

Domani

Ron, have a look at the link in the above question. That is more or less the thing I'm thinking about, only on a larger scale. It hardly costs any effort to pull that sand bag up and provides 15-30 minutes of electricity for the LED bulb. These old type of standing clocks with weights were not massive, too. They could run for a day or a bit longer on one time "charging" by pulling the weights up.

SolTun

http://opensourceecology.org/wiki/Compr ... Water_Pump

Ronmaggi

Got it, I thought you meant using the falling water to generate electricity it assist in pumping the water back up. You really meant using gravity as a storage device for energy, ala a grandfather clock. Sounds interesting.

Domani

Domani

Ronmaggi wrote:

Got it, I thought you meant using the falling water to generate electricity it assist in pumping the water back up. You really meant using gravity as a storage device for energy, ala a grandfather clock. Sounds interesting.

Yeah, wondering if one pumps water up to that hight (or lower/higher) in small portions with little use of energy, it might even be possible to get more out of it then there goes in, energy wise speaking. If you look at the example of the gravity lamp, it takes a couple of seconds to pull the sand back up to produce 15-30 minutes of energy for the LED bulb. Expressed in watts, how much energy input would that be, to pull up that sand back by hand?

Ronmaggi

You use more energy pulling up the sand bag than the led uses.

tom77

Domani wrote:

Ronmaggi wrote:

Got it, I thought you meant using the falling water to generate electricity it assist in pumping the water back up. You really meant using gravity as a storage device for energy, ala a grandfather clock. Sounds interesting.

Yeah, wondering if one pumps water up to that hight (or lower/higher) in small portions with little use of energy, it might even be possible to get more out of it then there goes in, energy wise speaking. If you look at the example of the gravity lamp, it takes a couple of seconds to pull the sand back up to produce 15-30 minutes of energy for the LED bulb. Expressed in watts, how much energy input would that be, to pull up that sand back by hand?

I once was thinking about using solar power during the day to pump water to a height where it is stored and is released during the night time so that I wouldn't need a battery bank.. but then even if it was just a little backyard system with a 1000L fish tank I would need anywhere from perhaps 6000-12000 litres of essentially sump water (I wouldn't turn the entire fish tank over every hour at night but instead run more through it during the day. but still all the nutrients would dilute in that amount of water and I would need two sumps.. one higher than fish tank and one below.. totally different than what your talking about but perhaps just pumping water to a height and running it through a turbine to create power would work although I imagine the losses would be quite high... although solar panels are getting super cheap and there would be very little other hardware between the panels and the water pump.

tom77

Domani wrote:

Stuart Chignell wrote:

I'm remembering why I stopped looking at airlifts as a primary pumping option.

Smaller bubbles make for a more efficient airlift but require a greater operating pressure. Combined with losses in the compressor makes for an inefficient water pump.

If you look at the table it shows that while the fine bubbles are more efficient the efficiency is still pretty low (<20%).

Where airlifts could claim back some ground is if you also include their ability to transfer gasses into and out of the water. Hard to calculate absolute effciencies but you could relatively easily work out relative efficientcies.

Ie if airlifts move 10,000L/hr and add 500g of O2/hr how does this compare with a dedicated water pump and some other way of aerating the water.

A dedicated water pump can have an efficiency upwards of 70% but if you have to inject a certain amount of air at a certain depth to get a certain level of aeration as well then the efficiency of the airlift at moving water might not count.

This reminds me of a long drawn out discussion about the difference between productivity and efficiency.

I think that if the system is designed for use of air lifts it might be more economical to run than a system with separate water and air pumps. Increasing the efficiency of the air lifts will probably enhance that effect. After all, circulating the water doesn't have to be with a large head. Exaggerated, circulation could be done through all tanks and beds with less than 150mm difference in levels. At least, that's where I am in thinking about the optimal layout.

I have read some of those long threads about airlifts (got too technical for me) but what I got out of it was that it was either a negligible benefit in efficiency for the air lifts or they were actually worse... but if you were not just looking at efficiency there seemed to be some possible benefits from a reliability and maintenance point of view at least in dirty water applications (probably not as applicable in wells?) I mean a pump has impellers or something mechanical to clog, however airlifts have all the complicated moving bits up away from the dirty water and use the air to directly contact particles.. even in a well wouldn't it be easier to maintain a pump on the surface than a submersible type pump?

Domani

Tom, running the water through a turbine downwards will not be efficient and much of the stored energy would be lost in the process. I think you see that right. The key is to use the weight of the water and have gravity doing the work.

Concerning airlifting, I've read this paper that states that it is efficient and economical if the system is designed for it. http://www.ecw.org/prod/205-1.pdf
The article makes sense to me.

tom77

Have you got some links to good info on using water for energy storage, it would be interesting for me? when you speak of the weight of water and gravity do you mean that you would recover the energy mechanically? like pulleys and cogs like in clocks etc?

Domani

Links not yet, but when I've found something I'll post them here. Indeed, pulleys and cogs like in grandfathers standing clocks.

Domani

On my sailing boat I used a fender filled with water as a counter weight to get myself single handed up the masts. I hoisted the fender up with a block, hooked up the line to my climbing harness and pulled myself up with hardly any effort. Worked like a charm...

tom77

I have no doubts it works, it will just be interesting to see some research done on efficiencies of such systems.. there are always losses, it's just a matter of how much at what cost.
Although this topic got me looking into 'pumped storage hydro'.. it seems to be done on a very large scale but I can't seem to find examples of anyone doing it on a small home scale.. would be a fun experiment.. or at the very least it could make a cool looking water feature, perhaps with a big over the top water wheel

Domani

I knew it would not be an original idea, since most things are already somehow invented. Look at these video's to get an idea of what I'm thinking about. No idea if the guy got it all working at the end, but it's a start.

Domani

And another one!

Backyard Aquaponics A place to discuss aquaponics

Domani Aquaponics Ne Thailand

Backyard Aquaponics
A place to discuss aquaponics