Chile’s copper mines are using substantially more electricity for each tonne of metal they produce as declining ore grades increase the physical demands of mining, a trend that could intensify pressure on the country’s power system as the industry electrifies.
Average copper grades reported by Cochilco fell by a third to 0.62% in 2024 from 0.93% in 2005. Over the same period, sector electricity intensity — total electricity consumed by Chilean copper mining per tonne of mine copper produced — climbed 68% to 5.16 MWh per tonne from 3.07 MWh.
There is a strong long-term relationship between falling grades and rising electricity intensity, but the link doesn’t establish causation. Across the 20 annual observations, copper grade and electricity intensity have a Pearson correlation of -0.91, while a simple linear regression in levels produces an R² of 0.82.
The distinction matters as Chile, the world’s leading copper-producing country, considers the electricity requirements of future supply. Cochilco projects electricity demand from copper mining will rise 20.2% to 33.2 TWh in 2034 from 27.6 TWh in 2025, while copper production increases just 8.3% over the same period.
Grade pressure
Copper grade affects how much material is associated with each tonne of contained metal. In a simplified benchmark where recovery, dilution and other operating conditions remain unchanged, the amount of ore required for a fixed quantity of copper moves approximately with the inverse of grade.
On that basis, the decline to 0.62% from 0.93% implies a 50% increase in the ore burden. Producing the same amount of contained copper would require 1.5 times as much ore as in 2005 if all other conditions remained unchanged.
That calculation is a mechanical benchmark rather than an estimate of the actual increase in tonnes mined or processed. Still, it illustrates the physical pressure that declining grades can exert on mining operations.
Putting electricity intensity and the inverse-grade benchmark on a common 2005=100 basis produces a similar long-term direction. The inverse-grade index reaches 150 in 2024, compared with 168 for electricity intensity.
The gap between those indices should not be interpreted as a measure of the contribution from other factors. Nor does the regression result mean declining copper grades explain 82% of the increase in electricity intensity.
Year-to-year data reinforce that caution. The correlation between annual changes in grade and annual changes in electricity intensity is only -0.32, considerably weaker than the relationship between their long-term levels. Average grades also improved to 0.62% in 2024 from 0.59% in 2023 even as electricity intensity continued to rise.
The evidence is therefore consistent with declining grades acting as a structural pressure on electricity requirements rather than as a stand-alone explanation for annual changes.
Other factors can affect electricity consumed per tonne of copper, including processing routes, recovery, mine configuration, water requirements and the energy mix. The historical data considered here don’t identify their individual contributions, and this analysis doesn’t attempt to separate them.
Electrification effect
Electricity intensity is also becoming a more complicated measure of mining performance as operations replace activities traditionally powered by fossil fuels with electrical systems.
A mine that replaces diesel haulage with electric or trolley-assisted equipment, for example, may consume more electricity per tonne while cutting diesel use and potentially reducing both total energy consumption and greenhouse-gas emissions.
Rising electricity intensity therefore shouldn’t automatically be interpreted as deteriorating overall energy efficiency. Increasingly, the indicator reflects two structural forces: the additional physical effort associated with lower-grade deposits and the transfer of energy demand from fossil fuels to electricity.
Those forces have fundamentally different economic and environmental implications, even though both can push electricity consumption per tonne higher.
For Chile, the distinction has consequences beyond individual mines. The historical increase in electricity intensity, combined with further electrification, suggests future copper production could require substantially more generation, transmission capacity and mine-site electrical infrastructure.
Cochilco’s forecast underscores the scale of that challenge. With mining electricity demand projected to grow more than twice as quickly as copper production through 2034, the electrical requirements of each additional tonne are becoming increasingly important to planning future supply.
The next tonne of Chilean copper may require more electricity not only because lower grades make it physically harder to produce, but because a growing share of the energy needed to mine it will come from the electrical system rather than fossil fuels.
* Patricio Faúndez is Economics Analyst Leader at GEM Mining Consulting.
