Widespread installation of advanced electrical conductors would help accelerate decarbonisation of the US power grids by creating carrying capacity on the network more quickly and cost-effectively than expansion of large-scale transmission, according to a new report partly funded by the American Council on Renewable Energy (Acore).
“We find that the incremental capacity generated by deploying advanced conductors to address just 25% of ageing infrastructure needs in NERC [North American Electric Reliability Corporation] regions can facilitate the interconnection of at least 27GW of zero-carbon generating capacity annually over the next ten years,” wrote Jay Caspary and Jesse Schneider, who authored the study delivered by research house Grid Strategies.
That forecast increase has the potential to reduce power sector CO2 emissions by 2.4 billion metric tons, equivalent to those from 22 average-size coal-fired plants. During the same period, energy savings from newly created transmission capacity would save consumers at least $140bn.
NERC is a non-profit regulatory authority whose missions is to ensure the reliability of the bulk power system in the US, Canada, and part of the Mexican state of Baja California.
The report, Advanced Conductors on Existing Transmission Corridors to Accelerate Low- Cost Decarbonisation, also details that their use will notably lower line losses originally built with conventional conductors, which increases their efficiency.
The ability to reconductor existing structures and raise loading limits provides an effective way to make the grid more robust, address congestion, and increase transmission capacity at critical points on the grid. Extreme weather has stressed grids in California and Texas where congestion is also slowing interconnection of more solar and wind energy.
Department of Energy data shows that parts of the US grid are more than a century old and 70% of transmission lines have been in service more than 25 years. Heavy-duty, long-haul transmission to tap abundant solar or wind resource in remote areas of the country’s interior can take 10 or more years to permit and build.
“We need two to three times the amount of transmission capability today to support the decarbonisation goals of the future,” said Caspary on a webinar. “What can we do now? We can take full advantage of existing transmission assets and critical rights of ways that need replacement of aging conductors.”
President Joe Biden has set goals to decarbonise the national grid by 2035 and for the US to achieve net-zero by mid-century.
The Grid Strategies report was funded by Acore, along with the National Resources Defence Council, and private firms CTC Global, Lamifil, Taihan USA, and TS Conductor.
Advanced conductors are built around a composite and/or carbon core and provide higher capacities and lower losses compared to traditional ones with aluminium and steel cores. They can also operate at higher temperatures and can do so for an extended periods with low sag, which allows for a much greater increase above normal loading capabilities.
While these benefits and the ability of advanced conductors to double the power density on paths using existing structures, their application is in the US is limited – usually on lower voltage 69kV or 138kV facilities that “often become congested when contingency conditions occur on a parallel extra high voltage path”, according to the report.
Caspary said that the price of advanced conductors is 10-20% more than conventional ones and this is a hurdle for many state utility regulators.
“They typically look more for least cost solutions. The lowest possible cost to provide the requested service in the very near-term,” he said, adding he hopes regulators will start looking at “maximum benefit metrics when it comes to economics. No-regrets solutions.”
Historically, utilities have also preferred to rebuild existing facilities because that makes their life easier when it comes to maintenance and operations. They can deal with it down the road and walk away from it in 20, 30 or 40 years, according to Caspary.
“We may not have the luxury of doing that. It is very costly. The outages are very disruptive to the operation of the transmission system. We need to find ways to be smarter in the use of advanced transmission technologies such as advanced conductors,” he said.
With climate change, more cost-competitive renewables, and growing public pressure for cleaner energy sources, change may be in the offing.
“I think you are going to see some existing announcements by some of the more utilities in the near-term that are going to move toward advanced conductors as their standard conductor for critical lines,” he said.