Because grid batteries are currently used as peak supply - if a production of power plants suddenly falls of by 10 GW or there is 10 GW additional demand, you h

Because grid batteries are currently used as peak supply - if a production of power plants suddenly falls of by 10 GW or there is 10 GW additional demand, you have to quickly provide that 10 GW of power before other (cheaper) additional production can be ramped up.