It was during his 18 years at Tesla that Drew Baglino realised how inadequate the US energy grid had become. The technology connecting to the network was advancing rapidly, but the infrastructure underpinning it had changed little for decades.The economy of the 21st century is still drawing on a power system built in the 19th century, he says. “It just isn’t able to keep up.”The backbone of the electricity grid is the transformer — a crucial, largely unseen device that increases voltage so elect...