Tech Insights

Aluminum Alloy May Enable Stronger, Faster Power Transmission

May 24, 2024 by Liam Critchley

Could a stronger, more conductive aluminum alloy upgrade outdated transmission cables?

In power lines, conductive cables transfer energy over long distances across the grid to distribute it where needed. Most power lines are made from metallic conductors and alloys. Cables comprise an aluminum outer wrap housing a less conductive but stronger core material, often steel. These are known as aluminum-conductor steel-reinforced cables.

NanoAL, a materials research startup, is developing a stronger, more conductive aluminum alloy steel-core cable designed to replace conventional wires for improved energy transmission. 

 

Transmission cables.

Transmission cables. Image used courtesy of Pexels

 

Traditional Power Line Weaknesses

Most power lines are based on a 1908 patent and require upgrading to carry more electricity to meet modern society’s growing energy needs. Studies show if the U.S. uses commercially advanced conductor materials in the grid’s power cables, it could save consumers up to $140 billion and prevent 2.4 billion tons of carbon emission over the next ten years.

Developing advanced material systems tailored to grid cables rather than off-the-shelf conductor materials can further improve these numbers. Advanced conductor materials might reduce the need to increase the number of power lines across the U.S. while also decarbonizing the power grid.

Most transmission lines today are built from aluminum wrapped around a steel core. Steel's strength protects the lines from sagging in adverse weather conditions, such as high winds and snow, and slows general material degradation over time. However, despite steel’s mechanical benefits, it is not an ideal conductor material. Steel is about only 10% as conductive as aluminum. While making the cables completely out of aluminum would increase conductivity, the lines would weaken, sag, and break quickly.

 

Conductive but Strong Aluminum Alloy

NanoAL has been improving the interplay of mechanical strength and electrical conductivity by developing an aluminum alloy 60% stronger than other aluminum alloys today. It is 700% more conductive than traditional steel cores. Moreover, the alloys are 19% stronger than traditional steel cores, with a tensile strength of over 500 MPa and a specific strength of 189 MPa*cm3/g.

 

NanoAL’s alloy compared to other materials

NanoAL’s alloy compared to other materials. Image used courtesy of NanoAL

 

Copper is the more conductive metal used in other cable applications but is unsuitable for transmission lines for several reasons. NanoAL’s aluminum alloy has an electrical conductivity approaching 48% of standard annealed copper, showing its high conductivity level and potential.

NanoAL’s proposed cable uses its aluminum alloy Nano 6000-T9 as its core. It’s wrapped in an aluminum 1350 alloy with over 99.5% aluminum but a relatively high iron and silicon content (compared to other alloying elements) to improve its strength through solid solution strengthening.

As the U.S. builds more wind and solar plants in remote locations, transmission lines will be exposed to harsh weather, such as strong winds, sun rays, and localized heating. Cables must be improved to withstand these environmental effects. Switching out the steel core for conductive but reinforced aluminum materials could also make transmission cables more efficient. In the long run, the improvements could save money and help reduce the grid’s carbon footprint by reducing energy loss.

 

Collaborations and Scaling Potential 

NanoAL aimed to develop an aluminum alloy with a strength comparable to steel, directly substituting for the high-strength steel used in power lines.

NanoAL worked on the project with General Cable, a subsidiary of the Prysmian Group. These two companies have developed aluminum alloys for various applications in the past. The collaboration helped NanoAL define the customer and application requirements for the cable materials and the scale-up processes required. Next, NanoAL and General Cable will develop commercial potential and scale the material.

 

Advancing in CABLE Competition

NanoAL is a finalist in the Department of Energy’s competition for Conductivity-Enhanced Materials for Affordable, Breakthrough Leapfrog Electric and Thermal Applications (CABLE). The winners will receive $500,000 to develop their materials further.