Why does the energy transition need more copper?

The future is bright for copper. The energy transition provides a major driver for new demand, adding potentially 25-50% to the copper stock in use and increasing annual demand by 20-30% depending on the phase of the transition. This observation is well documented in the scientific press, amply discussed in media, but rarely do we hear the question why the energy transition needs so much copper. Here are a few reasons that help explain the why:

[1] Small is beautiful when it comes to copper

When it comes to copper use, small machines use relatively more copper than big machines. Take transformers for example: the biggest transformers designed can reach 1,100 Mega-Volt-Ampere, roughly equivalent to the capacity of a large power station. Such transformer will weigh over 400 tons and contain 60 tons of copper. If the copper use per kg of copper would be proportional to its rating, we could expect that a transformer using 60 grams of copper could serve 1,100 volt-ampere of power, i.e. one millionth of its big brother. Actually, it serves only 11 VA or a 100 times less than expected. Put differently, it requires 100 times more copper per unit of power than the largest machines. Similar conclusions can be drawn for rotating machines such as motors and generators.

Hence, smaller units need more copper per megawatt (or per unit of power).

[2] Variability leads to more megawatts

In addition to more copper per megawatt, we need more megawatts. A conventional thermal power station may operate e.g. 5,000 to 7,000 hours per year of 8,760 hours. Renewables are weather-dependent. The ratio of their annual energy output and rated power defines their number of full-load-equivalent operating hours, which varies between 900 and 1500 hours for solar photovoltaics to around 4,500 hours of offshore wind power plants. Onshore wind power falls somewhere in-between these two extremes.

Replacing conventional power plants with renewables requires between 1.5 - 8 times more megawatts. In practice, a mix of renewables will be used and units of power may increase by a factor two to three for the same amount of energy produced.

[3] Dispersed power needs to be collected by grids

Photovoltaic power systems use lots of land, about 1 ha/MW which can produce 0.9 - 1.5 GWh/year. A large thermal power station of 1 GW running 7,000 hours would be replaced by 5,000 - 7,000 ha of PV power stations, covering 50-70 km2 (or 12,500 - 17,500 acres). All that energy needs to be collected by a wire and cable network. E.g. in photovoltaic power systems, about 25% of copper use is in the modules and 75% in the wiring. And when it comes to wind power systems, each offshore wind farm leads to a new copper demand of a few hundred tons in the cabling.

Hence, there is at least as much copper in connections than there is in equipment.

[4] Variability also leads to a need for redundancy and the use of combined solutions

Electricity needs to be delivered to customers at the right time. The balancing of supply and demand in a near 100% renewable electricity system requires a carefully designed mix of flexibility on the supply side, flexibility on the demand side, grid level integration and an appropriate use of energy storage. All these additional systems require copper to a varying extent.

Hence, deep integration of renewables leads to additional hardware and redundancy solutions requiring copper. For example, batteries currently use 0.4 kg of copper per kWh; smart buildings use 10 to 30% more copper in their electrical installations.

[5] The energy transition is electricity-intensive

The rapid decarbonisation of the electricity system, in combination with the unsurpassed end-use efficiency of electricity drives electrification in the energy transition, i.e.:

• the electrification in OECD economies of heating & cooling in buildings and of passenger transport;
• the indirect electrification of hard-to-decarbonise sectors such as the process industry, long-haul transport and seasonal storage through e-fuels and green hydrogen.
• the electrification of rural and peri-urban communities in developing economies for energy access.

Over the past century, we observed a strong relation between copper and electricity use. Going forward, this link is particularly apparent in the area of emobility.

[6] Energy efficiency further adds to copper demand

In cables, transformers and rotating machines, losses can be reduced economically through using more copper. This is somewhat a secondary effect compared to the above-mentioned trends for renewables, energy flexibility and electrification but it is significant, and moreover, energy efficiency can partially offset the additional electricity use due to electrification and improve the cost-effectiveness of the energy transition, making it more acceptable for energy users.

High efficiency motors and transformers use typically 20% more copper. Upsizing a cable requires 50% more copper.

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Last update: July 27, 2021