In 1882, at 57 Holborn Viaduct in London, the Edison Electric Light Company started using a coal-fired steam engine to generate electricity for the first time. Its 125-horsepower (93-kilowatt) generator, known as Jumbo, provided power to around 1,000 streetlights. Unfortunately for its investors, it did not do so as cheaply as gas could, and closed four years later. But a precedent had been set.Today the world has 27m times as much coal-fired electricity-generating capacity: 2,470 gigawatts (GW)...