Electric grids fed by renewables need a different kind of plumbing

When you hear the word “transistor”, you probably think of the little on-off switches which sit in their millions on silicon chips. If a name comes to mind it is probably William Shockley, the Bell Labs researcher who invented that particular sort of semiconductor device in 1947, or Gordon Moore, who first spotted the trend for them to get smaller, cheaper and better all at once (and who died in late March).

When a power engineer hears the word, though, they may well think of switches built for brawn, rather than miniaturisation, and of Bantval Jayant Baliga. Born in Chennai in 1948, Mr Baliga applied the principles of semiconductor physics to the control of currents, rather than to calculations. In 1980, while working for General Electric, an American conglomerate, he patented a new kind of semiconductor which is quietly changing the world: the insulated gate bipolar transistor (IGBT).