Comment by chrisseaton
7 years ago
> I have not heard about an wind/air turbine used to refill an air compressor (without electricity). Not sure how that would work
A wind turbine turns rotation into electricity.
A motor turns electricity into rotation.
A compressor uses rotation to compress gas.
You can remove the electricity between stages 1 and 2.
I think the part that isn't intuitive to everyone is how to "accumulate" potential energy if you don't have batteries/capacitors. Like how I can't fill my car tire with my bike pump. There's... there's magic missing. Something that takes a small amount of pressure and overcomes the huge pressure the other way. Check valves or whatnot.
It's easier to perceive when you think about a massive turbine that can grind out a ton of electricity and power a compressor that by default produces a lot of air pressure.
These tools are really neat to me. I love the idea of things like a hand crank radio, pulleys, and long levers.
Presumably you could fill the tire of a transport truck with the bulb from a blood pressure cuff and a lot of time, but it's not intuitive to me what the mechanics are in between those two things.
> Like how I can't fill my car tire with my bike pump.
Um. Yes, you can. It just might take a little while. You can fill 100 psi road bike tires with a hand pump. A 30-40 psi car tire is not a problem.
Have done this, can confirm, it does take a while :) like tricept workout kind of while, but it does work... (for expediency I used a floor pump serfas or something like that)....
yeah the pressure isn't a problem, the volume can wear you out though :)
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> how to "accumulate" potential energy if you don't have batteries/capacitors
That's what the compressed gas is - it's potential energy. It's like a battery.
> Like how I can't fill my car tire with my bike pump.
Why not? Because you can't pump hard enough and it's not strong enough to hold the pressure needed? You can build a stronger pump, and you can use a lever or gears (same thing really) to compensate for your strength if you can't pump any more.
> Presumably you could fill the tire of a transport truck with the bulb from a blood pressure cuff and a lot of time, but it's not intuitive to me what the mechanics are in between those two things.
Again that's just a 'lever' problem - you can't squeeze the bulb hard enough, so add a lever (and you may need to make the bulb stronger.)
I personally understand these things. I'm trying (and failing) to communicate that mechanics can be less intuitive than electricity. I regret this post. :)
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Pressure differential is analogous to voltage and mass flow to current, I think we are all on the same page about that.
The sorely missing bit is the equivalent of those amazing DC/DC step-up/down voltage regulators that have revolutionized the application of electricity in recent decades (all the way from tiny electronics to massive HVDC networks), and/or an equivalent of the AC transformers that fulfilled a similar role before. Actually AC is missing in its entirety, there's just no practical way of transmitting power via soundwaves.
The closest pneumatic equivalent to DC-DC converters are coupled turbines, e.g. turbochargers or high bypass turbojets. But those are not just far beyond households appliance scale, they are also limited to the high mass-flow/low pressure differential, but practical applications of pneumatic storage are the opposite.
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You can also lift a car or truck with your hands... and a jack.
Energy is force times distance. If you can only exert a tiny force, you can compensate with enough distance, providing the losses in the system aren't too great.
> I think the part that isn't intuitive to everyone is how to "accumulate" potential energy if you don't have batteries/capacitors. Like how I can't fill my car tire with my bike pump. There's... there's magic missing.
As others have pointed out, you can! If you're rather patient. They've even got compatible valves!
And you can think of a pneumatic tire as a kind of battery -- potential energy is roughly the volume times the pressure differential.
Flywheels are acceptable replacements for batteries. I'm not sure if the Amish use them for energy storage, but the rest of us do.
Wind turbine rotation turns the compressor. (With the right gearing)
Edit: I must have skipped over your last sentence. I thought you wanted all those electrical steps for some reason!