Instead of more centralised batteries like the one at Hornibrook SA (!00Mwhrs) why cant we use our own parked cars? You would need three phase power, cooperation from Tesla & compensation from power companies. However you would also be able to charge at Chardemo levels 50kWs. Ill assume that house hold levels are 50kWs capable. 2000 cars gves us 100 MWhrs. The equipment would also need a grid feeding inverter & internet connection to control export. Our cars could supply this much power for at least an hour & more if you had a large solar system. With the rapid uptake of EVs I think this idea has merit in the future.