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Low pressure pneumatic grid (1 to 4 psi) to use small wind, small hydro and small solar power?

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I have used low pressure air and a simple "airlift pump"  to cycle water around a "pallet  Garden" since August.  This meant that very little water was being used but the plants were growing really well.   the air comes from an aquarium bubble pump and it is about 1 psi.  The pallet garden is almost 20 ft from the little bubble pump.   Recently I decided to do something similar in my greenhouse, but it is 120 ft from the little pump and there is no electrical socket close.  So reluctantly I bought another 120 ft of 1/4 inch tubing to send the air to the greenhouse.  I didn't expect it to work at that distance.  But it is working great. Why not use air instead of electricity to move the energy from "toy" windmills in gardens? Or from low head small water power?  I bet anyone could make a compressor to make 1 PSI.  It is orders of magnitude easier than making a direct water pump or converting the energy to electrical and then back again in a pump.  An airlift pump is just a vertical tube in the water.    How simple is that!   and it is darn cheap too.  You can use this for pumping water (Highest I ever got was 18 ft with 1 psi) or just bubbling air into a fishpond or to actually move the water in small water features.   Or of course in the pallet garden or in aquaponics.  And even thought this energy is useful at that scale it can never ever be made worthwhile to share it electrically.  But maybe your grid could extend to your neighbours garden too?  You could have an interconnector if you or they have a bit of excess pneumatic power!

8 Replies

steveastrouk (author)2013-01-18

There was a high pressuer hydraulic grid for cranes and elevators in Manchester, near where I live in the UK. It was working until the 1970s. The steam engine that ran it is in the local science museum.

gaiatechnician (author)2013-01-21
For the grid to work you need all sorts of valves and logic circuits.  Here is a Diode invented By Tesla!
lemonie (author)2013-01-19

It's can't be more energy efficient to run a compressor, as compared to an efficient direct-driven pump. However, it could be better than a less-efficient pump and it's a small-idea to scale-up and see. I also think that the stall-speed on the turbine would be lower, so you'd get movement across a wider range of wind-speed. Add-in a gas-pressure regulator and you could limit the maximum (water) flow rate.


gaiatechnician (author)lemonie2013-01-19

Thanks, Lemonie, I think working across a range of speeds is one key. The sun and the wind and even a little stream are so darn variable! But a grid with all 3 or even with your solar panel pointing one way, your neighbours a different direction etc, would even a lot of the variability out. So you can gather energy from a little hobby windmill or turbine in your back yard or on a hill 200 meters away or you have a 15 watt solar panel driving a tiny compressor in a sunny spot or a tromp in a stream and pipe the air to where you want it. If you have a grid with your neighbours, variable production would be evened out but also variable consumption too! Many years ago, I used a tromp in a stream and sent the air up a pipe and attached it to a metal pipe down through a chimney and through a wood fire and into a room. The air with maybe only 10 watts of power driving it made a huge difference to room temp because it collected heat from the chimney. For cycling water round my greenhouse I am currently using a 3 watt bubble pump and it is 120 ft away from the greenhouse, and it pumps air through 1/4 inch tubing at about 1 PSI. By the way it pumps way too much water for the greenhouse. (I circulate water through planters with it so the planters never go dry).

lemonie (author)gaiatechnician2013-01-19

I had an idea that an ultrasonic transponder might de-gas water and generate air (if you've enough dissolved gas in it), but I don't know much more about it than that.
I like experimentation, it's how people learn things - keep going!


rimar2000 (author)2013-01-17

Interesting efect. Did you discovered it?

gaiatechnician (author)rimar20002013-01-18

Hi, Steve, useful to know! I am finding old (and new) "fluid logic" stuff really interesting. I asked on a few computer related forums, no replies so far. I asked a high up computer guy today about what sort of air pressures it worked with and he was honest "I haven't a CLUE about it!"

gaiatechnician (author)rimar20002013-01-17

No, not at all, People have used high or medium pressure pneumatic grids before. Apparently they were even used in the 1800's in Paris to run Elevators, etc! O, and below have a couple of general links about pneumatics from another discussion on a different forum about this idea. Here is a neat link to a 4 psi science project from a university, http://www.youtube.com/watch?v=JW6nlS3Dcn8 in a science museum. And here is something about a commercial one http://www.pondreports.com/2008/09/windmill-air-compressor-pumps.html and http://www.koenderswindmills.com And if you read the why, you will find that they are simpler and more reliable than the electrical systems.. It is pretty cool stuff. http://en.wikipedia.org/wiki/Pneumatics has a link to pneumatic logic. Which is at http://en.wikipedia.org/wiki/Fluidics Maybe it works at low pressure too? Even though it would not be a "cool" project, a fluid logic gate or two would be a great thing to see on instructables! If it is good enough for modern jet engines, it should be good enough for us!  The other discussion was depressing because everyone asked why I didn't just use electricity.  So many people have had their imagination coached out of them.  Maybe the steam punk people would like it?