ADELAIDE, AUSTRALIA - SEPTEMBER 29: Elon Musk during his presenation at the Tesla Powerpack Launch Event at Hornsdale Wind Farm on September 29, 2017 in Adelaide, Australia. Tesla will build the world's largest lithium ion battery after coming to an agreement with the South Australian government. The Powerpack project will be capable of an output of 100 megawatts (MW) of power at a time and the huge battery will be able to store 129 megawatt hours (MWh) of energy. Tesla CEO Elon Musk has promised to build the Powerpack in 100 days, or he will deliver it for free. (Photo by Mark Brake/Getty Images)