Energy efficiency
Energy efficiency takes on a central role in the conversion of previous energy systems. All other things being equal, higher electrical conductivity means higher energy efficiency or more compact designs with the same efficiency.
Copper has the highest electrical conductivity of all non-precious metals. Its properties therefore make it the preferred conductor for wires, cables and electrical devices, which use about two-thirds of the copper produced worldwide. Copper also conducts heat much better than other metals, which is very important for heat exchangers and heat sinks in electronic components. In terms of conductivity, only silver performs better. The copper industry is developing innovative materials with higher conductivity to further improve the range of applications.
The compactness of copper conductors saves on other materials such as dynamo sheet, housing, insulation, connectors and cable support systems. Without copper, electrical components such as motors, transformers and cables would be about 20% larger for the same efficiency. Unlike other conductors that must be made from primary metal, copper conductors can be made from 100% recycled material. The energy required for recycling is about 20% of the energy required for primary production (from mining). In addition, the relatively high value of copper, combined with its ease of recycling, is a key factor in recovering end-of-life products that would otherwise be lost.
Copper conducts heat much better than other metals
Compactness of copper conductors saves materials
With the same efficiency and performance, a copper conductor has a cross-section about 40 % smaller than that of a comparable conductor made of aluminium. This compactness saves, among other things, on magnetic materials, on materials for motor or transformer housings, on insulating materials for wires and cables and on cable ducts in urban environments. This leads to obvious economic (lower costs) and environmental (less material) benefits.
Energy losses can be further reduced by increasing the conductor cross-section. While this cannot be increased endlessly, the environmental optimum for transformer and motor windings, electric cables and overhead railway lines is a much larger conductor size than required by current standards, which only aim at electrical safety (compliance with permissible operating temperatures). The CO2 emissions saved during the service life of the equipment per additional kg of copper range from 100 to 7,500 kg, depending on the application.
Reducing energy losses by increasing the conductor cross-section means that less electrical energy has to be generated, transmitted and distributed. Between 500 and 50,000 kWh of primary energy is saved over the lifetime of an installation for each additional kilogram of copper. It can therefore be more advantageous not to exploit the better conductivity of copper by reducing the conductor cross-section and – as described above – saving space, but by leaving the conductor cross-section as it is and reducing losses through the better conductivity of copper.
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, allows the use of thinner wall tubes for the higher pressures required for more environmentally friendly refrigerants. In addition to direct energy efficiency improvements, more compact systems save material as well as economic and environmental costs.
Improving energy efficiency
Studies have shown that the energy consumed each year by electric motors in industry could be reduced by around 30 TWh by 2020 if all motors were brought up to today’s technical standards. That is enough to make several large power plants superfluous. Similar savings potential can be achieved with the use of efficient lighting systems. In both areas, copper materials are the ideal efficiency boosters.
When it comes to energy efficiency, copper’s role also extends beyond the product level. Through copper wires and cables, it also acts at the system level to save energy through control and regulation technology. These energy and thus carbon dioxide savings at the system level are often orders of magnitude higher than the savings at the product level.
Transformers
A transformer is a component that is counted among the electrical machines, although in principle it contains no moving mechanical parts. It absorbs electrical energy and also emits electrical energy again. In the process, however, a high voltage becomes a low voltage and a small current becomes a correspondingly larger current – or vice versa – without there being a direct conductive connection from the input to the output side. Instead, in a transformer there are two coils on a common iron core through which the energy is transmitted magnetically. One coil consists of many turns of thin wire, the other of a few turns of thick wire. The wire is usually made of copper, in some cases of aluminium, which, however, does not conduct as well as copper, which is why the aluminium wire has to be thicker. The electrical power is calculated from voltage times current. Since it is not possible to drive the electrical current as high as desired, because the conductors would have to be immeasurably thick, very high voltages have to be used to transmit high power. The traditional electricity grid works with centralised large-scale power plants, some of which feed more than 1 gigawatt [GW] – a billion watts – into the grid. This has always required transmission networks of corresponding capacity. The new electricity system, which is to supply industrial areas in southern Germany with wind power from the North Sea, must also transmit enormous amounts of power in as concentrated a manner as possible over as few routes as possible. For this, very high voltages of e.g. 220 kilovolts [kV] – 220,000 volts – will be used. If the line can then carry a current of 1,000 amperes [A], for example, this results in a transmittable power of 220,000 V * 1,000 A = 220,000,000 watts = 220 megawatts [MW]. To transmit this power at the same rate as the end consumer voltage, the lines would have to be more than one metre thick – and it still wouldn’t work.
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