how can we store ac power generated...
is it stored using capacitance please explain????

 

Capacitors store electrical charge (energy). Given that "power" is the time-rate dissipation of energy could you be clearer about the question "how can we store ac power generated"?

Dave

 

By using a giant flywheel connected to a generator I don't know how useful it would be.

 

They call that a "compulsator," don't they?

 

So it does exist then?

 

One way is to use "excess" power to pump water up into a resevoir. When demand increases, the water flows down through turbines to generate power.