A Saudi-controlled real estate firm says it plans to break ground early next year in Egypt’s new capital on a $1 billion, 50-storey office tower that aims to be the first of its kind to be powered by clean hydrogen. The sophisticated design and high price tag represent a bet by Magnom Properties, a subsidiary of Saudi industrial group Rawabi Holding, that international clients will be drawn to the new capital, a city for over 6 million people being built from scratch in the desert east of Cairo. It is also a bet on clean hydrogen, produced using renewable energy and not yet proven at scale, as…