Tesla has activated a lithium-ion battery big enough to power 30,000 homes in South Australia. Tesla, the US technology giant, has started up the world’s largest battery and plugged it into South Australia’s power grid. Being one of the world’s biggest coal exporters, Australia has also long been seen as one of the world’s worst polluters. South Australia is scrapping its coal-fired power stations and switching to renewable energy. Al Jazeera’s Hannah Hoexter reports.