A $500 million government authority would double Australia’s energy efficiency and move the country towards 90 per cent renewable energy by 2030, under a plan to be unveiled by the Greens today. Greens leader Richard Di Natale is set to today announce plans for the new agency, RenewAustralia, which he said would drive the country through a 15-year pipeline of clean energy projects. Dr Di Natale is also set to outline a $1 billion Clean…