Very few compressed air systems run at full load all of the time.  An air compressor can be one of the largest electrical consumers in a facility and there are considerable opportunities for energy savings with a variable speed air compressor.  While variable speed drives have decreased in cost over the last few years, there will still be a premium to pay over a standard fixed speed compressor.  A basic supply side compressor load study, such as Ingersoll Rand's Intellisurvey, can determine the potential return on investment for an upgrade to a variable speed drive.

This load study consists of monitoring the compressor amp load and plant pressure response for a typical week of production.  By reviewing the amount of time the compressor spends at less than full load, energy savings by incorporating a variable speed drive compressor, can be calculated.

Variable speed drives can be integrated into a new compressor, or in some instances, added to the existing fixed speed compressor.  In addition to energy savings, another advantage of variable speed is the ability to more tightly control overall plant system pressure as the compressor is now reacting to a set target pressure rather than a 10psi or on/off-line pressure setting.  Variable speed compressors are often used as a 'trim' unit in a multiple compressor system whereby the fixed speed compressor is maintained as a full load base compressor and the variable speed ramping up and down as needed to make up any additional requirements - the most energy efficient method available.