9V valves

Dear reader,

I need for an aplication a proportional  9 Volt output. is this possible with the system running on 24 Volts? Because if i would use a COUT the voltage would be 24 V.

Is it maby possible to use a PWM output? 

if so, how do i use PWM?

Another option is to run the system on 9V, is this stable to use?