Back in March 2016, an AI program developed by Google made headlines when it bested world Go champ Lee Se-dol in what has been called humanity’s most complex game.

What few know is that to achieve the decisive victory, the AlphaGo program had to be powered by nearly 2,000 central processing units (CPUs) and 300 graphics processing units (GPUs). The electricity bills were as high as US$3,000 a game at the time, Massachusetts Institute of Technology (MIT) professor Han Song said in a recent speech at Tsinghua University.