Tech Insights

Small but Mighty: Transmission Cables Use Nanotech To Boost Conductivity

May 23, 2024 by Liam Critchley

TS Conductor has designed carbon nanotube composite fibers to create stronger, faster,  and more efficient transmission cables.

Transmission lines are still made of aluminum-conductor steel-reinforced materials, based on a patent from 1908. However, traditional steel materials lack sufficient conductivity and are a barrier to faster transmission. 

Many advanced alloys and composites offer conductivity and structural properties without needing steel. TS Conductor, a California-based company, has created a transmission cable using carbon nanotube (CNT) composite fibers to provide conductive and reinforcement properties to the cable’s core. The cable could accelerate grid modernization and increase capacity three times over existing structures.

 

Conductive cable.

Conductive cable. Image used courtesy of TS Conductor
 

What Are Carbon Nanotubes?

CNT composite fibers act as an additive material in another host. CNTs have a very high electrical conductivity that various composites can utilize. CNTs also have excellent inherent strength—100 times steel’s strength at just a quarter of the weight—but their small size means they can’t be used alone in many applications, especially those needing a “bulk” material.

Various bottom-up fabrication and spinning methods can enable CNTs to align within composite fibers. Combining CNTs within the host achieves the best possible conductive and mechanical properties because CNTs are 1D materials. The electrons only flow along the longitudinal axis (in one dimension). Aligning also improves the elastic modulus and fracture toughness of the composite.

CNTs can enhance the host material's strength and improve conductivity in applications where strength is required, such as power lines. Pairing CNTs with an already conductive but less mechanically robust material, such as aluminum, helps achieve a much more rounded set of properties for transmission line applications without needing heavier steel alloying elements.

 

CNT-Enhanced Cable Core for Transmission Lines

The cable’s core combines conductivity and strength by substituting some carbon fiber with a small amount of CNTs to generate beneficial properties in the same composite. The core is encapsulated with a highly conductive aluminum alloy to provide lifetime protection against environmental degradation, including moisture plasticization, polymer oxidation, and UV/ozone degradation. It’s also possible to embed optical fibers into the cable to make them “smart,” which could benefit digitalized smart grids.

Transmission lines in the US have been created from various design approaches, all with different structural loading criteria. Weather events—such as wind, snow, and storms—produce loads that can exceed the line's loading criteria, causing corrosion, tension, friction, and structural failure.

Rising global temperatures also affect transmission lines. These temperatures reduce the thermal rating of transmission lines—the maximum current for a specific temperature—causing the lines to sag significantly, threatening the grid’s stability. Therefore, transmission lines with materials that can withstand higher temperatures are needed to prevent sagging.

 

How CNT Can Improve Transmission Lines

Upgraded transmission lines improve their structural loading characteristics and gain structural uniformity across the grid. CNT-enhanced cables can provide enhanced structural support and thermal protection and present themselves as a plausible alternative.

The CNT-enhanced cable from TS Conductor could triple (300%) the capacity of existing transmission lines, but TS Conductor eventually aims for 500% capacity. The cables can reduce line losses—the power lost between the energy source and its intended destination—by 50%.

The core doesn’t expand under thermal loads (high temperatures in remote environments, for example), eliminating the potential for thermal sagging and keeping the power line taut and able to withstand high winds. The core is also lightweight but with high strength, an ideal property combination for structural supports, making it more resilient and durable.

 

Video used courtesy of TS Conductor

 

TS Conductor claims CNT-based cables can replace traditional transmission lines using existing utility poles, thus saving time and costs. 

 

CNT Cable Future

While TS Conductor’s cable is not yet widely used, the technology is gaining attention. The Department of Energy selected the company as a finalist in its CABLE competition, which carries a $4.8 million funding prize for winners. The 2024 BloombergNEF Pioneers Award also recognized the company's solution to ease renewable energy transmission bottlenecks.