Copper or aluminum cable? Cost comparison for underground cable and grid connection

Particularly with cables such as NA2XS(F)2Y or NAYY for wind turbines, the choice of material determines costs, performance and service life. Copper impresses with its high electrical conductivity, while aluminum scores with low costs and low weight. But which material is technically and economically the better choice in the long term? This article provides a detailed analysis of the advantages and disadvantages of both options.

Electrical and Mechanical Properties Compared

Copper has been the preferred material for electrical wiring for decades. It offers high conductivity and excellent mechanical stability. Aluminum, on the other hand, is significantly lighter but has lower electrical conductivity. This means aluminum cables require a larger cross-section to transmit the same current.

Comparison of Properties

Property	Copper	Aluminum
Electrical Conductivity	58 MS/m	35 MS/m
Density (g/cm³)	8.96	2.70
Corrosion Resistance	Very high	Medium (oxidation)
Mechanical Strength	High	Medium
Weight	High	Low
Price per ton	€8,000 – 9,000	€2,300 – 2,500

Although aluminum offers weight savings in transport and installation, it requires larger cross-sections to achieve the same performance. This can impact space requirements in cable trays and mechanical stability. Additionally, aluminum is more prone to oxidation, which can lead to contact issues, whereas copper maintains its conductivity over long periods without significant quality loss. In humid or salty environments, such as offshore wind farms, this can be a crucial factor.

Costs: Acquisition, Installation, and Operation

Material Costs

The biggest advantage of aluminum is its lower purchase cost. While copper prices fluctuate significantly, aluminum remains relatively stable. In a direct comparison, aluminum cables such as NA2XS(F)2Y often perform better economically for long installation routes and large power lines – despite their lower conductivity compared to copper. Cost per ton (as of 2024):

• Copper: €8,000 – 9,000
• Aluminum: €2,300 – 2,500

For long cable routes, this price difference can add up to a substantial amount.

Installation Effort

• Copper cables are heavier, making transport and installation more labor-intensive.
• Aluminum cables are lighter, simplifying mounting and logistics.

Especially in offshore wind farms or hard-to-reach locations, aluminum can offer significant advantages.

Operating Costs and Energy Losses

• Copper cables have lower transmission losses due to their superior conductivity.
• Aluminum cables require larger cross-sections to transmit the same power, increasing costs for cable tray construction and materials.

Aluminum saves on initial purchase and installation but may become more expensive in the long run due to higher energy losses.

Lifespan and Maintenance

Another crucial factor is the durability of the materials.

Corrosion Behavior

• Copper is highly resistant and barely oxidizes.
• Aluminum forms an oxide layer that can degrade electrical contacts.

In humid or salty environments, such as offshore wind farms, aluminum can become problematic.

Mechanical Durability

• Copper cables are more robust and less prone to material fatigue.
• Aluminum is softer and requires special connection techniques to ensure long-term reliability.

Maintenance Effort

• Copper connections remain stable for decades.
• Aluminum connections require regular inspections to prevent contact issues.

Copper lasts longer and requires less maintenance. Aluminum may lead to higher long-term costs.

Longevity matters: while copper remains maintenance-free for decades, aluminum requires regular inspections to prevent performance losses.

Environmental Friendliness and Sustainability

Environmental impact is becoming increasingly important in modern energy industries. Sustainability doesn’t start with operating a wind farm—it begins with selecting the right materials for its infrastructure. Copper and aluminum differ not only in production but also in recyclability and overall environmental impact.

Energy Consumption in Production

Copper is an excellent conductor, but its extraction and processing are highly energy-intensive. Mining requires massive open pits or underground mines, consuming vast resources. Refining copper also demands extremely high temperatures, leading to significant energy use. Studies show that producing one kilogram of copper requires four to five times more energy than the same amount of aluminum. Aluminum, in contrast, is extracted from bauxite, which is more abundant than copper ore. However, refining aluminum requires the energy-intensive Hall-Héroult process (electrolysis). The advantage? Recycling aluminum uses only about 5% of the energy required for its initial production.

CO₂ Footprint and Environmental Impact

Copper production generates significantly more CO₂ emissions than aluminum—if the aluminum is sourced from recycled material. While both metals are recyclable, copper’s primary extraction has a higher environmental toll. Another key factor: lifespan and maintenance. Aluminum cables wear out faster than copper cables and need more frequent replacements. This means that aluminum’s environmental benefits rely on consistent recycling after use.

Recyclability

Both copper and aluminum are fully recyclable, but in practice, there are differences:

• Copper has a high recycling rate because of its high value—it’s rarely discarded.
• Aluminum is easier and cheaper to recycle, but a significant portion of global production still depends on virgin bauxite.

Long-Term Sustainability in Wind Farms

Aluminum excels in production efficiency and recycling, while copper’s durability and lower maintenance needs make it a long-term sustainable choice. For wind farms, choosing the right material is also an environmental decision. Conclusion

• Aluminum wins with its lower CO₂ footprint in production and excellent recyclability.
• Copper lasts longer, requires fewer replacements, and thus also contributes to sustainability.

Ultimately, the best choice depends on whether short-term efficiency or long-term durability is the priority.

Which Solution is Best for Wind Farms?

Comparison of Key Factors

Factor	Copper	Aluminum
Efficiency	Better	Higher losses
Cost (Material & Purchase)	More expensive	Cheaper
Installation Effort	Heavier, more complex	Lighter, easier
Operating Costs (Losses & Maintenance)	Lower	Higher
Corrosion Resistance	Very good	Medium
Lifespan	Longer	Shorter
Environmental Impact	High energy consumption	Better with recycling

Recommended Applications

• Aluminum is ideal for long medium-voltage routes, where weight and cost are crucial factors.
• Copper is the better choice for grid connections, substations, and critical areas, where efficiency and longevity matter most.

The best solution is often a combination of both materials to balance cost and efficiency effectively.

Copper or Aluminum – Which choice pays off?

The decision between copper and aluminum cables depends heavily on the specific requirements of a wind farm project. Aluminum offers lower material costs and reduced weight, making installation easier. Copper, on the other hand, excels with higher efficiency, lower maintenance costs, and longer lifespan. The best approach is often a strategic combination of both materials:

• Aluminum for long transmission routes where cost and weight matter.
• Copper for critical grid connections, ensuring long-term reliability and efficiency.

This way, costs can be optimized while maintaining operational security. Anyone wishing to purchase cables such as NA2XS(F)2Y should consider the installation environment, the load and the project period in addition to the pure material price. For many onshore wind farms, aluminum offers a clear cost advantage – for others, the more robust NAYY copper cable is worthwhile. Need expert advice on cable selection?
Get in touch with our specialists at KLZ—we’ll help you find the perfect cable for your wind farm project!