Christophe wrote:buck
and it's a teacher who says that!
A regulator or step-down would have been more suitable!
A regulator does not waste energy (or so little) as we can hear in your message when you say:There is a loss of pressure without creating mechanical work
It was an image, an explanatory metaphor ... You’re a little overheated
You want me to plug you into a step-down chopper 
or better a 4 quadrant chopper.
For practice, I entrust the task to Nlc who is much better than me.
More seriously ... Precisely, for operation in stationary regime (a constant power called by the driver who drives at constant speed), the flow rate is fixed roughly by the volume and the engine speed.
And this being said, if you have fun running the engine on the lowered pressure, you have less power, while with the same flow rate without regulator, you could have more power. This is what the regulator does
Good design, in fact, would be to have expansion pistons placed in series, and as the tank pressure drops, we would not use the pistons at the end of the chain, because only the former would be enough to lower the fluid pressure to atmospheric pressure.
This flexible multi-stage expansion design would also not prevent the famous "heaters" to take up a little pressure with the external heat (the adiabatic expansion cools the fluid).
The big problem with compressed air machines with high pressure storage is that they require a relaxation machine with an ultra-adaptive operating range: from 300 (full bottle) to a few Bar (empty bottle) for the pressure of Mdi admission !!
In my opinion, having such machinery is not justified economically, also, they use a pneumatic motor with small range of intake pressure, and in passing they must pre-relax in a dead volume without moving parts, and waste part of the energy there.
Hihihihi she will stay in the anal this one!
