This is greatly innacurate. The author is confusing "spinning reserve", which is when any dispatchable generator is running at less than 100%, with the natural regulatory properties of synchronous rotating machines. Because in the same way energy is stored as kinetic energy on a turbine, it is also in similar amounts in wind turbines (which the author says it's not), but also in most non-eletronic regulated motors from grid consumers. If this was in any way true, it would mean conventional DC grids couldn't work, and they did 100 years ago. Also, there is no reason for turbines, or generators, to rotate at 50Hz (3000rpm). They usually rotate much slower. Please punish your scripter!