Source: adapted from Koomey, J.G., S. Berard, M. Sanchez, and H. Wong (2011) "Implications of Historical Trends in the Electrical Efficiency of Computing", IEEE Annals of the History of Computing. Vol. 33, No. 3. pp. 46-54.
Computations per kWh, Selected Computers, 1946-2009
Energy consumed per computation is one way to measure the productivity of computing devices. Similar to Moore's Law, the amount of computations per kWh has increased in an exponential fashion since the introduction of the first vacuum tube computers in the 1940s and 1950s. Each decade the amount of power required to perform a computation decreased by a factor of 100. The improvement of this ratio is particularly important in the context of mobile computing devices that rely of battery power to operate.