FOR MORE than a decade the Tamaya power station in the Atacama desert in northern Chile powered its local region using diesel. Today a shimmering array of solar panels stands in place of the dirty generator. Engie, the French utility that owns the power station, converted it into a solar-energy and battery-storage plant earlier this year. Juan Villavicencio, the company’s boss in Chile, describes the site as a place where “the past and future of energy infrastructure meet”. Others share his vision. Developers, governments, startups and utilities around the world are turning former fossil-fuel power stations, and old oil and...