Copper has a superior electrical and thermal conductivity, is highly durable, and can be 100% recycled, without any loss in performance. Here, we sum up 10 good reasons and figures why copper should be a material of choice when it comes to building a more sustainable energy system.
Copper as a good conductor of electricity and heat
1. Adding 1 kg of copper saves 100 to 7,500 kg of CO2 emissions
Every conductor in the electrical system has a built-in resistivity. This means that part of the electrical energy that it carries is dissipated as heat and is lost as useful energy. For a given conductor diameter, those energy losses can be reduced by choosing a material with a high electrical conductivity. The electrical conductivity of copper is second only to silver and is 65% better than aluminium.
These energy losses can be further reduced by increasing the conductor diameter. While this cannot be increased endlessly, the environmental optimum, for transformer and motor windings, electrical cables, and traction overhead lines, lies at a significantly higher conductor size than prescribed by current standards. Carbon emissions saved per additional kg of copper over the lifetime of the device are between 100 and 7,500 kg depending on the application [1-7].
2. Adding 1 kg of copper saves 500 to 50,000 kWh of primary energy
Reducing energy losses by increasing the diameter of the copper conductor means that less electrical energy needs to be generated, transported, and distributed. Between 500 and 50,000 kWh of primary energy are saved over the life cycle of the system for each additional kg of copper used [1-7]. Moreover, these savings delay the need to invest in new grid capacity and other infrastructure.
3. Adding 1 kg of copper saves the economy 24 to 2,400 euro
The energy savings that result from increasing the conductor diameter lead, in the vast majority of cases, to a reduction in the life cycle cost of the system. For intensively used electrical devices, such as cables, transformers and electric motors, the cost of energy losses over their lifetimes are many times the initial purchasing cost. The 500 to 50,000 kWh that are saved by each additional kg of copper, will save the EU economy between 60 and 6,000 euro (at an industrial electricity price of 0.12 €/kWh and a primary energy factor of 2.5).
4. Using copper results in a highly efficient heat transfer
As with electrical conductivity, the thermal conductivity of copper is second only to silver. This makes copper the preferred material in applications where heat transfer is involved, e.g. in air-conditioning and solar thermal water installations. Its high thermal conductivity reduces the heat losses and the carbon emissions associated with them.
Copper as an environmentally well-performing material
5. Copper can be 100% recycled without any loss in performance
Unlike most aluminium conductors, which need to be produced from primary metal, copper conductors can be made from 100% recycled material. In 2010, 44% of Europe’s total copper demand was sourced through recycling. The energy required to recycle is approximately 20% of that required for primary production (from mining). Moreover, the relatively high value of copper, combined with its easy recyclability, is a key driver in the recovery and recycling of end-of-life products that would otherwise be lost.
6. Compactness of copper conductors saves on other types of materials
For the same efficiency and power, a copper conductor will have a cross section that is approximately 40% smaller than that of the equivalent aluminium conductor. This compactness saves, among others, on magnetic materials, on materials for motor or transformer housing, on insulation materials for wires and cables, and on the cabling ducts in urban environments. This brings about obvious economic (lower cost) and ecological (less material) advantages.
A similar advantage exists in the use of copper tubes for air-conditioning systems. The excellent thermal conductivity of copper, combined with its high mechanical strength, enables the use of smaller diameter tubes that can withstand the higher pressures required for more environmentally friendly refrigerants. Apart from the direct energy efficiency improvement, more compact installations save on material, as well as on economic and ecological costs.
Lifecycle benefits when using copper
7. Copper and its characteristics are durable
Copper is a highly durable material that will continue to function throughout its lifetime without a significant loss in performance. The copper component is highly unlikely to be the reason for a device to reach the end of its useful life.
8. More copper means higher safety and reliability
Degradation (e.g. of cable insulation or motor windings) is often the result of excessive heating caused by the conductor needing to transport a higher current than it is designed for. Optimising the conductor diameter consequently reduces the risk of electrically induced fires, increases reliability, extends service life, lowers maintenance costs, and reduces the need for a back-up installation. Copper conductors also facilitate high quality joints (welded or bolted). As these are often weak points, durable joints significantly improve the reliability of the energy system.
9. Copper has a high mechanical strength
The mechanical strength of copper is of high importance for electrical appliances, which have to withstand the forces of short circuit currents, and for thermal applications that have to withstand high pressures. Combined with its excellent electrical and thermal conductivity, the high mechanical strength of copper, and its alloys, delivers resource efficiency through miniaturisation.
10. Copper is highly corrosion resistant
Because copper develops its own adherent protective coating, it has an excellent resistance to corrosion in all kinds of common environments including atmospheric air, potable water, soil, and even sea water and a wide variety of chemicals. Secondly, since copper is at cathodic extreme of the metal series, it is very insensitive to galvanic corrosion. As a result, copper retains its excellent electrical and thermal conductivity over the years. Neither does corrosion influence the mechanical strength of copper, which is one of the reasons why the material is highly durable.
 EPD, May 2000, Product Specific Requirements for Rotating Electrical Machines, available from www.environdec.com
 European Commission - DG TREN, 1999, Save: Technical, economical and cost-benefit analyses of energy efficiency improvements in industrial three-phase induction motors
 THERMIE, December 1999, THERMIE STR-1678-98-UK: the Scope for Energy Saving in the EU through the Use of Energy-Efficient Distribution Transformers, available from www.leonardo-energy.org
 Leonardo ENERGY, R. Targosz (ed) et al, February 2005, Global energy savings potential from high efficiency distribution transformers, available from www.leonardo-energy.org
 Egemin Automation, 2011, consultancy note: Modified Cable Sizing Strategies/Potential Savings vs. Copper Usage
 Frederik Groeman, July 2000, Optimal reduction of energy losses in catenary wires for DC railway systems, ref 98430138-TDP 00-12709, available from www.leonardo-energy.org
 Frederik Groeman, November 2001, Benefits of upgrading the overhead line of a DC railway line in the Netherlands – a simulation case study, available from www.leonardo-energy.org.