How to actuate 24V solenoids from 3.6V batteries
You want to power a 24V 900ma solenoid (21.6W) from a battery rated at 3.7V 3.4AH (12.58WH)? You could build a charge pump to make 24V from 3..3.7V, but (a) your battery certainly won't last very long between charges, and (b) you should expect significant losses from the charge pump, so your battery should be expected to last an even shorter time between charges.

Your thought of storing energy in a coil would consume a lot of extra energy, too, and as @JohnD pointed out would give you unpredictably high voltage spikes.