Australian iron-ore titan Fortescue Metals Group approved a $550 million green hydrogen project in Arizona, the centerpiece of an initial slate of projects aimed at recasting the company founded by billionaire Andrew Forrest as a clean energy giant.

The Phoenix Hydrogen Hub, in Buckeye, Ariz., was backed by directors in a $750 million, three-year investment plan announced Tuesday that also includes a green hydrogen project in Australia’s Queensland state and a project aimed at producing iron using renewable energy in Western Australia, where Fortescue runs its giant iron-ore mining operations.

Three years ago, Fortescue outlined plans to branch out from iron ore and build a globally significant clean-energy business. The path hasn’t been smooth. Fortescue has come under rising scrutiny from analysts and investors over limited detail on its energy plans and faced an exodus of executives, including both the chief executive and chief financial officer of its lucrative iron-ore business.