Origin Energy chief executive Frank Calabria says the major electricity and gas supplier’s huge increase in first-half profit compensates for the “unsustainably low” returns of a year ago, and will provide the capital to fund the energy transition.

Speaking after Origin posted a $700 million surge in benchmark net profit for the six months to December 31, Mr Calabria said people needed to remember that a year ago the electricity and gas supplier was struggling to make any money from its electricity business as wholesale costs soared.