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Fascinating history, thanks. I came across two incarnations of the trompe idea on Youtube that might be of interest.

The first was what the author describes as a hybrid of a trompe and a water ram. He used a small stream and 8' of head to accumulate air in a PVC pressure vessel to 60psi.


The 2nd was of a guy who got a grant from US DOI to use a trompe to help cleanup iron polluted water at an old mining site. The compressed air aids in oxidizing the iron to cause it to settle out.


Tyler August


Dr. Millar's HAC Demonstrator is installed in the Big Nickel Mine at Dynamic Earth, a geology-based science centre in Sudbury, Ontario, Canada. Part of the agreement with the science center is that the public has access to view the experimental facility and ask questions of the researchers.

Research is ongoing, so if you're ever in the area, it's worth checking out. One thing they are currently exploring is adding various salts to the water at the HAC demonstrator to reduce gas solubility and increase efficiency even further.

kris de decker


@ akb

Thanks, interesting. George Fleming also wrote me that the trompe could be used to reduce the dead zone in the Gulf of Mexico:

"It could inject air into the water while bringing cold bottom water up to the surface, like a Salter Sink, and producing bubbles at the surface which would increase reflectivity of the water, reducing warming. The compressors could be powered for free by the wind. This would work for any dead zone in any waters".

John Davies


Locomotives running on compressed air have a long history - http://www.douglas-self.com/MUSEUM/LOCOLOCO/airloco/airloco.htm.

Often used for short distances where range wasn't a problem, e.g. shunting, or for environments where a steam engine was hazardous, e.g. underground.

Logan Simmering


"Obviously, compressing the air mechanically only works with windmills and not with solar PV panels, which do not produce mechanical energy"

Solar thermal systems could be used to produce mechanical energy, as seen here




Couldn't return air shafts provide wind tunnels to exploit the air for power?

Charles R. Patton


Mentioned in article:

"Once again, it pays to look to the past for inspiration. Surprisingly, the holy grail of “isothermal” air compression – in which no waste heat is produced at all – was found at least 400 years ago. The hydraulic air compressor – or “trompe”, as it was originally known – was an Italian invention first mentioned by name in 1588, but possibly already known in Antiquity."

A very old 7th century as referenced in:

Roman forge, the "herreria de compludo" in Spain uses (it has been restored) a trompe for pressured air to run the "blast" furnace and various forge charcoal beds around the water wheel powered forge hammers. So it appears that the trompe concept existed at least 1300 years ago. As it was Roman, the concept may have been passed down through the generations as it is very simple and reliable with a good supply of water.

bobby mobby



I was wondering if it would make sense to couple an off-grid CAES system as described in the other article


with a 8bar manually operated air compressor? Not sure if such a thing exists (not being a bike pump I mean). I imagine something like an exercise bike or a big wheel to turn... Something that would allow to fill in less than one hour a few pressurized bottles.

Does that even make any sense?

bobby mobby


Hi again,

I was thinking something like:




What do you guys think?

Would that make sense to couple this with a CAES multi-bottleoff-grid system & to decharge to create electricity or use it with tools?


kris de decker


@ bobby mobby

That makes sense and we actually built it for the human power plant: https://krisdedecker.typepad.com/.a/6a00e0099229e8883301bb09c3cf1d970d-pi

The image shows the hand powered version, but later we converted it to pedal power. More here: https://www.humanpowerplant.be/human_power_plant/prototype-human-power-plant.html

We used a very old compressor and both the hand and foot powered drive were very crude. And yet, it worked very well. It would work even better using the machines that you link to (and thanks for that!).

Brian White


What about very low pressure air production and usage? I made mini trompes directly powering airlift pumps on a stream in Ireland starting around 1987 and one worked for about 15 years. I have a youtube video about it, "world's simplest pump". It used 200 to 300 liters per minute of water falling half a meter as its power and it pumped water to sheep at, I think, 5 meters above the stream and to cattle at 3.5 meters above the stream. Pumping in the airlift pump was by plug flow directly up and by slug flow on an incline. Since 2013 in Canada, I have used a mains powered pond air pump to power mini airlift pumps that cycle water in my garden planters and greenhouse. They use 1 meter water pressure or less (1.5 psi or less) on my "low power pneumatic grid. It currently runs 9 air lift pumps, in 2 greenhouses and a couple of planters. I also used it to run nft hydroponics over 2 summers.

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