Innovative aluminium-calcium composite promises breakthrough in power transmission

The U.S. Department of Energy's Ames National Laboratory, a leading institution in material science, is now in the field-testing phase of a pioneering high-voltage overhead power conductor. This new conductor, an aluminium-calcium composite, represents a significant leap forward in long-distance power transmission. Developed and patented by the esteemed scientists at Ames Lab, the aluminium-calcium conductor is lighter and stronger and boasts at least 10 per cent lower line losses compared to existing materials, potentially enhancing the reliability and performance of the nation's electrical grid.

In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions.

Ames National Laboratory is a U.S. Department of Energy Office of Science National Laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies, and energy solutions.

For over fifty years, aluminium wires with a steel core have been the industry standard for high-voltage overhead conductors. This combination of dissimilar metals presents numerous challenges, particularly in response to weather events like ice, wind, and storms. However, many of these issues can be mitigated using a uniform material, such as the aluminium-calcium composite.

Progression of the material from a bar, which is refined into a pole, then the pole is stretched into wire

Source: U.S. Department of Energy Ames National Laboratory

Iver Anderson, the project's lead researcher, detailed the new conductor's composition and benefits. The aluminium-calcium composite comprises microscopic calcium filaments that reinforce the aluminium, providing a lightweight yet strong alternative. While aluminium is an excellent conductor of electricity, it is typically too weak to be used alone in overhead conductors. Adding calcium eliminates the need for a heavy steel core, simplifying the design and substantially improving grid efficiency and durability.

As field testing commences, the potential for this innovative conductor to revolutionize power transmission and bolster the nation's grid resilience is becoming increasingly evident. This new conductor has the potential to significantly improve the efficiency and durability of the nation's electrical grid, marking a transformative shift in power transmission technology.

Anderson said, “While most metal composite experts would not think of using another weak metal to add strength to aluminium."

 “But, when calcium is co-deformed with aluminium (like striped toothpaste), they form very thin, long threads of calcium metal that make the aluminium stronger without making it more brittle.”

Anderson's team developed the composite, which is made from fine aluminium powder mixed with a small amount of calcium powder (less than 10 per cent of the total). They utilised their expertise in powder processing to address the manufacturing challenges of converting highly reactive calcium into the fine powder needed for the composite.

Ames Lab, in collaboration with a complete supply chain of seven U.S. companies, produced the first prototype sample conductor. This inclusive approach ensures that all stakeholders are part of the project, from the initial stages of compacting and co-forming the powders into a bar to the final manufacturing processes.

Recently, Ames Lab partnered with Mid-American Energy, a regional power company based in Des Moines, Iowa, to test the conductor in the field. They will install it between existing transmission towers to assess its real-world performance, testing it against variable electrical loads and the extreme weather conditions of the Iowa plains, including heat, cold, wind, and severe storms.

“Although the strength, conductivity, and other properties of individual strands of the new composite conductor have been measured in the Lab, measurements on the full conductor form in the natural environment are critical to industry acceptance of this new conductor choice,” said Anderson.

Using aluminium-calcium power conductors instead of traditional steel-core conductors for overhead transmission lines can enhance power grid resiliency and efficiency. These innovative transmission lines are crucial in advancing the nation's clean energy goals by efficiently transporting clean energy to where it is needed.

This research is backed by the Advanced Materials and Manufacturing Technologies Office (AMMTO), part of the U.S. Department of Energy's Energy Efficiency and Renewable Energy Office. The AMMTO fosters a globally competitive U.S. manufacturing sector by promoting the adoption of innovative materials and manufacturing technologies to support a clean, decarbonized economy.