Tesla CEO Elon Musk made good on his vow to the state of South Australia, installing a 100-MW, 129-MWh lithium-ion battery system in less than 100 working days at a 315-MW wind farm north of Adelaide. Musk promised to deliver the estimated $50-million system for free if Tesla fell short of its Dec. 1 goal, which proved to be the same day the already-completed, football-field-sized battery farm went into operation. The battery system comprises 210-kWh lithium-ion powerpacks, manufactured at Tesla’s Gigafactory, in Sparks, Nev. It is designed to offset intermittent wind conditions, which have contributed to numerous blackouts in South Australia in recent years. The system has the capacity to power more than 30,000 homes.