Electric motors accounted for around 46% of total electricity demand in Europe in 2021, with pumps, fans and compressors accounting for 70% of this. Many of these applications run at a constant speed, even if the load varies. Two studies conducted by the Fraunhofer Institute for Chemical Technology ICT on behalf of CEMEP (European Committee of Manufacturers of Electrical Machines and Power Electronics) now show that demand-based control using frequency converters could save up to 140 TWh (terawatt hours) of electrical energy per year - equivalent to around 5% of the EU's total electricity demand.

A frequency converter adjusts the speed of an electric motor to the actual demand. According to Fraunhofer ICT, the savings potential is between 10 and 70 %, depending on the device and load profile. The study examined electric motors for pumps, fans and compressors in EN performance classes between 0.37 and 1300 kW in areas such as water and wastewater pumps, heating and air conditioning technology, ventilation and industrial cooling and heating processes.

Highest potential for fresh water pumps

For fresh water pumps in particular, the researchers see an effect of 18 to 24 % less energy consumption. Around 50 % of pumps and 40 % of fans currently still operate at a fixed speed. In some applications with a constant load, such as swimming pool pumps or wastewater pumping, however, speed control does not bring any immediate advantage.

In addition to direct energy savings, frequency converters can be used to install smaller, more efficient devices that deliver the same performance at a higher speed. This was also confirmed by one of the studies for constant load applications such as the aforementioned pumps for swimming pools and wastewater pumping.

Further downstream savings effects are conceivable, for example, in systems in which the goods to be transported contain thermal energy, such as in the supply of warm air to buildings: if their throughput can be flexibly adapted to demand, less thermal energy is required overall. However, the available studies do not quantify such effects.

Saving 140 TWh of electrical energy in Europe would reduce CO₂ emissions by around 38 million tons per year - as much as is released when burning 14.2 billion liters of diesel fuel, according to the Fraunhofer ICT press release.