Incremental copper use improves equipment energy performance

Incremental copper use improves the energy performance of copper using equipment and appliances, thus benefiting the environment while lowering lifecycle costs in most cases

As the best conductor of electricity and heat among commercial metals, copper contributes significantly to improving the energy performance of electrical equipment and appliances such as motors, transformers, air-conditioners and heat pumps.  The reduction in energy usage per unit of output in turn reduces CO2 emissions at the power generating station, helping in the battle against global climate change.

Electric Motors:

Electric induction motors use enameled copper wires in the stator winding and either copper or aluminium in the rotors. During operation, there is a flow of current both in the stator and the rotor causing i2R energy losses. Other energy losses occur in the magnetic steel, bearings and fan. A reduction in the stator i2R energy losses can be achieved by redesigning the motor with higher cross-section conductors thus reducing the conductor resistance. This requires incremental copper. Further, in motors with aluminium rotors, a reduction in the rotor i2R energy losses can be achieved by substituting the rotor material with higher conductivity copper.

Transformers: 

Distribution and power transformers consist of two electrical windings coupled magnetically through a core made of magnetic material. The flow of current in the electrical windings causes i2R energy losses. Other energy losses arise in the magnetic core.  A reduction in the i2R energy losses can be achieved by redesigning the transformer windings with higher cross-section conductors thus reducing the conductor resistance.  This requires incremental copper.

Room Air-Conditioners and Heat Pumps:

A room air-conditioner transfers heat from an enclosed room in a building to the outside atmosphere, thereby cooling the room. An air to air heat pump is similar, but operates in reverse by transferring heat from the atmosphere to the enclosed room, thus heating the room. Both appliances are structurally similar and consist of two heat exchangers, one in the room and one outside. A refrigerant liquid absorbs heat and turns into a gas in one heat exchanger, and then delivers the heat in the other, cools, becoming a liquid again and then the cycle repeats. An electric motor driven compressor moves the refrigerant around delivering the energy needed for this thermodynamic process.

The heat exchangers are usually made of copper tubes due to its superior thermal conductivity. The energy efficiency of the appliances can be increased by increasing the heat exchange surfaces which results in incremental copper use.

Thus, it can be seen that the energy performance of the equipment and appliance groups described above improves with the incremental use of copper.  Various case studies have shown that adding just 1 kg of copper to electrical equipment and appliances can lead to lifetime savings of up to 5,000 kWh of electrical energy. On a conservative basis, this is equivalent to saving up to 2,500 kg of CO2 emissions and $350 in energy costs per kg of copper. In addition to the environmental benefits, this is a very good financial return on an upfront dollar investment in single digits!

References

  • VITO and BIOIS study for preparing the implementation of the new Ecodesign or Energy Related Products (ERP) Directive (2009/125/EC) related to power and distribution transformers, on behalf of the European Commission DG ENTR unit B1 OT2: Distribution and power transformers Tasks 1 – 7 Contact VITO: Paul Van Tichelen, Contact BIOIS: Shailendra Mudgal,ecotransformer.org 2010/ETE/R/106, January 2011
  • Drivers for Copper use in Power Transformers, S.A.A. Houtepen, J. Bloem KEMA, Arnhem 20 December 2011 , 74101182-ETD/SUP 11-2903
  • ECI Case studies – “$1M investment ‘’
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