The huge Chicago-based energy company Exelon generates enough electricity to supply millions of customers in 48 states and parts of Canada. Its wind and solar farms, hydroelectric plants and nuclear power stations also pump out a lot of valuable data about wind speeds, swings in consumer demand, the purpose and frequency of repair crew trips, and other details. In 2015, it started pooling this data in the cloud and trawling it for insights to make its power plants smarter.