More efficient motor-driven systems can reduce global electricity demand by 10%

18 May 2011

The first global analysis of energy consumption in electric motor- driven systems (EMDS) has been presented in a new report by the International Energy Agency (IEA).

Electric motors are used in a wide range of industrial systems, but also in many types of applications (such as pumps and compressors) in the commercial, residential, agricultural and transportation sectors. Examples of how motors are used within these sectors range from heating, ventilating and air conditioning systems, to escalators, lifts and fans.

“Typically,” the authors of the report explain, “electric motors are a component in a motor system, responsible for converting electric power into mechanical power. The energy use of a motor system corresponds to the electricity consumption of its motors plus a small additional quantity needed to power system controls.”

Largest source of electricity use

Researchers found that EMDS account for between 43-46% of all global electricity consumption, leading to about 6,040 Megatonnes (Mt) of CO2 emissions. This is by far the largest source of electricity use, easily outstripping lighting, which takes up 19% of the world’s demand.

Unless comprehensive and effective energy efficiency policy measures are put in place by 2030, the report concludes that energy consumption from electric motors will rise to 13,360 terawatt-hours (TWh) per year, and CO2 emissions to 8,570 Mt per year, more than one and a half times US annual CO2 emissions in 2008.

“End-users now spend USD 565 billion per year on electricity used in EDMS; by 2030, that could rise to almost USD 900 billion,” write the authors.

Stimulating savings

In order to address this daunting rise in cost and CO2 emissions, the report – Energy-Efficiency Policy Opportunities for Electric Motor-Driven Systems – proposes a comprehensive package of policy recommendations to help governments tap the huge potential for energy savings in EDMS.

These recommendations include introducing minimum energy performance standards in IEA member countries that are in line with international best practice for all major classes of electric motors, as well as ensuring that energy performance test procedures are developed for all motor types.

The analysis in the report finds that by using the best available motors on the market, about 4-5% of all electric motor energy consumption can be saved. On top of this, another 15-25% can be saved by linking these top-notch motors with cost-effective engineering solutions (both electrical and mechanical).

If these solutions are implemented, “the potential exists to cost-effectively improve energy efficiency of motor systems by roughly 20-30%, which would reduce total global electricity demand by about 10%”.

The road ahead

The report outlines the three major routes to achieving these savings, which are:

  • Using properly-sized and energy-efficient motors;
  • Using adjustable-speed drives (equipment used to control the speed of machinery) to match motor speed and torque to the system mechanical load requirements, which makes it possible to replace inefficient throttling devices and, in some cases, avoid wasteful mechanical transmissions and gears.
  • Optimising the complete motor system, including a correctly sized motor, pipes and ducts, efficient gears and transmissions, and efficient end-use equipment (fans, pumps, compressors, traction, and industrial handling and processing systems).

If all EMDS move towards the least life-cycle cost level using best available technologies, the authors calculate that in 2030, approximately 3,890 TWh of annual electricity demand would be saved, giving rise to savings of 2,490 Mt of CO2 emissions (equivalent of just under half the US’s annual CO2 emissions in 2008).

In order to assist countries in implementing these changes, the IEA has also produced a separate information paper, which provides a work plan for governments for delivering more energy-efficient EMDS. Walking the Torque proposes an achievable plan to improve efficiency of EMDS by 10-15%, which is half of the theoretically possible savings outlined in the other paper.

Photo: © GraphicObsession.