Comment by usrusr
7 years ago
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.
> DC/DC step-up/down voltage regulators
Interestingly, there is actually a hydraulic mechanism that's the equivalent of a boost converter with inductor, diode, and switching element:
https://en.wikipedia.org/wiki/Hydraulic_ram
It translates a low-pressure fluid with continuous flow into periodic high-pressure impulses. The inertia of the fluid is the hydraulic equivalent of the inductor, and a switching element (valve) closing suddenly causes a spike in pressure as the water decelerates suddenly, equivalent to a voltage spike as an inductor "wants to keep the current flowing".
But it usually operates with water, which has much higher density (hence inertia) than air, so it might not be very efficient (or might require much higher flow rate) in a pneumatic version.
You add a gear to your compressor. There is no need for an air pressure converter (which is effectively just an compressed air powered compressor with a higher maximum pressure).
Substituting pressure with more volume is highly impractical when storage is involved.