I agree that summing the two values to a GW seems disingenuous, but there are more scenarios than the two you described. For instance, it's possible to dischar

I agree that summing the two values to a GW seems disingenuous, but there are more scenarios than the two you described. For instance, it's possible to discharge the battery during the day, as well. If peak load is in the afternoon, the plant could be charging the battery during the morning and mid-day when specific demand on that plant is less than 690 MW, then discharge the battery to have (temporary) output of 1 GW.