Compressed Air Best Practices, Oct. 2016, by Michael Perlman.
http://www.airbestpractices.com/energy-manager/corporate-sustainability-programs/energy-management-considerations-today’s-drive-syst

"It is a fact that most of the energy loss in a system occurs in three areas, namely, the generation, distribution and conversion of energy into useful work, the last being accomplished through heat exchangers, pumps, motors and drives.  This paper will concentrate on the last product group."