It was at a press conference in Silicon Valley in 2010, where California governor Arnold Schwarzenegger was in the audience, that Sridhar launched Bloom Box, a small device that came to be called a power plant in a box, a technology that would revolutionise mobile power generation. Four years later, Sridhar’s start-up Bloom Energy and his invention, a fuel cell device, is a buzzword in the world of tech, drawing interest from companies like Google, eBay, FedEx and Wal-Mart.