Prince Turki bin Saud bin Mohammad Al Saud belongs to the family that rules Saudi Arabia. He wears a white thawb and ghutra , the traditional robe and headdress of Arab men, and he has a cavernous office hung with portraits of three Saudi royals. When I visited him in Riyadh this spring, a waiter poured tea and subordinates took notes as Turki spoke. Everything about the man seemed to suggest Western notions of a complacent functionary in a complacent, oil-rich kingdom. But Turki doesn’t fit the stereotype, and neither does his country. Quietly, the prince is helping Saudi Arabia—the quintessential petrostate—prepare to make what could be one of the world’s biggest investments in solar power. Near Riyadh, the government is preparing to build a commercial-scale solar-panel factory. On the Persian Gulf coast, another factory is about to begin producing large quantities of polysilicon, a material used to make […]