IBM has taken an impressive 18 of the top 20 places on the latest Green500 list. The Green500 ranks the world's fastest supercomputers according to their energy efficiency.

IBM has shamed its competitors, ranking by far the most environmentally friendly supercomputer maker. Eighteen of the top 20 systems on the Green500 list were made by IBM. The Green500 ranks supercomputers according to the number of floating-point operations per second they can perform for each watt of power consumed.