In the European Union, electric motors consume 46% of the electricity [1]. 70% of the motor energy is consumed by pump, fan and compressor applications. These applications often operate in partial load with reduced flow using mechanical flow controls like throttle valves, bypasses and dampers, that lead to a high energy consumption. As an alternative, a variable speed drive (VSD) could be used where the flow is varied with the motor speed. Because these applications power demand grows approximately cubic with the flow, small reductions in the speed result in high savings of consumed energy [2]. The energy savings per unit are between 10% and 75%, depending on the specific application and load cycles.

The energy saving potential of electric motors, that could be achieved by equipping the aforementioned applications with a VSD, is investigated and quantified. A calculation methodology is presented, that estimates the currently possible annual saving potential by using VSDs. Based on a literature review, the model uses the saving potential values of the applications and combines them with the market conditions. The market conditions consider the size of the market and the share of applications that could potentially be driven with a VSD. With the determined energy saving potential and the energy consumption, the total value of saved energy is calculated, which is estimated to 121,5 TWh per year for the EU. As well, the analysis shows, that fans and pumps still offer great energy saving potentials, whereas it is limited for compressors as many of them are already equipped with VSDs.

References

[1] Waide P and Brunner C Energy-Efficiency Policy Opportunities for Electric Motor-Driven Systems Energy Efficiency Series

[2] Almeida A T de, Fonseca P and Bertoldi P 2003 Energy-efficient motor systems in the industrial and in the services sectors in the European Union: characterisation, potentials, barriers and policies Energy 28 673–90