“In the past, grid operators and regulators considered line losses as an intractable problem that was part of life. It was also a problem they did not worry much about because costs were passed on to the consumer,” says Hiel. “Now, times have changed because we have been moving toward an environmentally-sensitive and low-carbon world and long-established business models and practices no longer rule.” He says that aluminum conductors with pultruded composite cores can reduce line losses by 25 to 40 percent.
ACCC is also stronger than ACSR. The hybrid glass fiber and carbon fiber composite core has a tensile strength of 2.2 GPa, while high-strength steel core has a tensile strength of 1.9 GPa. In addition, ACCC is 70 percent lighter and more compact than traditional stranded steel core. This allows for the addition of compact, trapezoidal-shaped aluminum strands around the composite core, which enables the incorporation of up to 28 percent more aluminum, says Hiel. “When you put more aluminum in the conductor, you increase its capacity to transfer power – what the industry calls ampacity,” he says.
Another advantage of ACCC relates to sag. Aluminum conductors expand when heated, causing slack between the towers. “Carbon fiber has virtually zero coefficient of thermal expansion, making it a far superior product than a steel strength member,” says Hiel. “The result is that the cable virtually doesn’t sag.” This, in turn, means that towers can be placed farther apart on new construction and rebuilds. For line refurbishment – called reconductoring – utilities can use existing infrastructure with ACCCs to double their capacity thanks to low thermal sagging properties.
CTC Global has manufactured the pultruded composite cores, which were patented by Hiel, for a decade. They have installed more than 40,000 miles of ACCC worldwide. Hiel says the potential for applications like this – and other composites in infrastructure – is endless. “The U.S. was built on steel, aluminum and concrete,” he says. “It needs to be rebuilt on composites.”