sentences:  Three gas turbines were utilised in an innovative manner to provide steam to one of the original steam turbines.These changes allowed for 1150 MWe of output to be delivered at 57% thermal efficiency compared with the plant's original 37%.The installed capacity of Peterhead increased to 2407 MWe in November 2007 following a compressor and combustion control upgrade on GT11, 12 and 13 making it the largest power station in Scotland ahead of Longannet.