Weight for weight, outside precious metals, copper is the best conductor of electricity and heat. It is hardly surprising, then, that about 60% of total copper use is for these applications.
Copper is used in high, medium and low voltage power networks, and copper conductivity is considered to be the standard by which other conductors are measured.
Blister copper is 96-99% pure, but there is a way to purify it further, through a technique called electrolysis. The unique combination of strength, ductility and resistance to creep and corrosion establishes this non-ferrous metal as the preferred and safest conductor for wiring in buildings. As an essential component of energy-efficient motors and transformers, it is used in a multiplicity of applications in manufacturing industries, all forms of transport and the domestic environment.
Copper's conductivity is almost twice that of aluminium, which makes copper the material of choice for high energy efficiency applications.
Copper wire has long been the preferred conductor material in the majority of cables used for power and telecommunications. Having high conductivity combined with ductility that makes it easy to draw down to close-tolerance diameters, it can also be readily soldered to make economic, durable connections. It is compatible with all modern insulation materials, but its good oxidation resistance means that it can also be used without any surface protection.
Insulation can be of lacquer or enamel types used for winding wires or of polymers for energy cables. Lacquers permit close spacing of windings to give the best efficiency in the coils of motors, transformers and chokes.
Busbars are robust conductors that function as electrical manifolds to distribute power from a single source to several users. Because of its good conductivity, strength, connectivity, ductility and resistance to oxidation, copper is the most obvious material to specify for the manufacture of busbars. High conductivity copper billets are hot extruded into a regular cross section, followed by drawing down to the necessary finished size.
Copper used for the manufacture of transformer windings is in the form of wire for small products and strip for larger equipment. For small products, such as magnet wire, the wire must be strong enough to be wound without breakage, yet flexible enough to give close-packed windings. Strip products must be of good surface quality so that insulating enamels do not break down under voltage. Good ductility is essential for the strip to be formed and packed, and good strength is needed to withstand the high electro-mechanical stresses set up under occasional short-circuit conditions. The properties needed for motor windings are similar to those needed for transformers, but with the additional requirement to withstand mechanical vibration and centrifugal forces at working temperatures.
While this sector is relatively small in terms of tonnage, copper plays a vital role in a number of small, high-tech applications. Copper or copper-base alloys are used in Printed Circuit Boards, in electronic connectors and lead-frames. In addition, it has long been used in the area of telecommunications, and is now increasingly used in IT, notably for the manufacture of microchips and in semi-conductor applications. Copper heat sinks allow dispersion of heat from high-frequency microprocessor and logic devices.
Thanks to its thermal conductivity, copper is an ideal material for the manufacture of all types of heat exchangers. It is easily fabricated and joined, and has excellent corrosion resistance. There are many different ways copper is used in heating and cooling applications. Copper can be used as a bulk material to radiate heat, as a pipe to transfer refrigerants, as a surface to collect the suns energy. It can be used as a heat pipe or part of a heat pump, as a fin material to transfer energy to and from the air or as a conductor of heat from one material to another. Simple or complex geometries can easily be made to maximise the cost efficiency of the transfer of energy.
Typical applications include radiators, air coolers, oil coolers and mobile air conditioners in transport; heat sinks for electrical equipment; calorifiers, heat pumps for domestic and industrial water heating and coils in air-conditioning and refrigeration units. With clever design copper can make heat exchanger units eco-friendly, economical and future proof for natural refrigerants.
Heat and cooling accounts for 48% of European final energy demand. 70% of that is low to medium heat below 250 degrees. Copper is used in solar thermal, geothermal and biomass applications.
Copper forms part of the materials presently used for photovoltaic solar cells, in the technology’s cabling, earthing, inverter, transformers and photovoltaic cell ribbons.