Austria’s largest state said Thursday that 100 percent of its electricity is now generated using renewable sources of energy. “We have invested heavily to boost energy efficiency and to expand renewables,” said Erwin Proell, premier of 1.65m-strong Lower Austria. Related: Argentina to generate 8% of energy from renewable sources by 2017 “Since 2002 we have invested 2.8 billion euros ($3bn) in eco-electricity, from solar parks to renewing (hydroelectric) stations on the Danube,” Proell told a…