Ok, I found a formula for the power in compressed air.

Pair [W] = Qv [m^3/sec] * Press [kgf/m^2]

300bar is ~3x10^6 kgf/m^2

Assuming you need 10hp to move the car at about half the max. speed (for
max. efficiency) you need 8kW for 6 hours (300km at 55km/h, half the max.
speed). That's 21600 seconds. Assuming 20bar equivalent pressure in the
motor (I just picked that number for reasonable end pressure in the tank -
20 bars is about ten times the pressure in a usual shop air end hose and a
usual working pressure in many pneumatic circuits):

Qv = Pair [W] / Press [kgf/m^2] = 8000/204000 = 0.04 [m^3/sec]

for 21600 seconds:

V = 864 [m^3]

which at 300 bars (15 times more than 20bars) are:

V1 = 57.6 [m^3]

which is less than their 90m^3 tank and very credible because I assumed
100% efficiency and theirs is lower, about 64% (based on the ratio of
their tank volume and V1 above).

There would be the small problem of keeping the whole thing from
*freezing* stiff, this requires about 6-7kW of heat *input* while working
(remember expanding gas cools it down). This is what they use the
compression of atmospheric air for I think.

Recharging the thing would require the same energy input (assuming 100%
efficiency as above but with their tank volume). Eg 6-8kW for 12 hours,
probably more like 6-8kW for 14-18hours to account for efficiency. 300bar
compressors do not grow on trees so I suppose it comes with the car (maybe
the motor is reversible and they have an electric motor to drive it).

Guy Negre was a F1 mechanic in a previous life I think, and he must know
what he is doing.

I liked the idea of soy oil lubrication ;-).

Peter

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