When Elon Musk promised South Australia that he could fix their power network by creating the world’s largest battery in 100 days or the service would be delivered for free, many thought he was bluffing. Now it seems the energy guru is set to get paid with construction on the battery already half finished. By solving South Australia’s power woes in less time than it takes to remodel your kitchen, Elon Musk is sending a message to the world about how possible it is to replace fossil fuels with renewables.