Harrison Street Station
It's capacity was originally 6,400 kW, which was twice that of the Adams Street Station making it the largest in the United States. When it was announced, many found the amount of power claimed as being wildly optimistic. But, when it opened in August 1894, that was its capacity.
Samuel Insull believed that the economy of scale provided by such a large station would offset its initial cost. Aside from this point, the size of the station allowed it to replace the Adams Street Station, which, by this time, had become both overloaded and obsolescent. Insull's optimism was rapidly justified; the Harrison Street Station reached its original capacity within the first several years, and was expanded to 16,200 kilowatts by 1903.