In our world, you can’t help but stumble across dozens of articles every week that talk about the importance of adding transmission capacity to support decarbonization goals. Southern California Edison, for instance, in its ‘Pathway 2045’ roadmap for enabling a clean energy future for California, predicts a 60% increase in demand and a 40% increase in peak load by 2045. Further, SCE predicts that the bulk of renewable generation resources will continue to be located far away from load centers.
While distributed generation assets, load flow controllers and dynamic line rating equipment will help to some extent, the need to increase the capacity of the existing transmission infrastructure is essential - especially considering the time it takes to plan and secure approvals for new transmission lines.
Fortunately, a number of leading utilities such as NV Energy, American Electric Power, Southern California Edison and dozens of others have begun using advanced conductors to increase the capacity of existing transmission lines. “Reconductoring” with advanced conductors allows crews to pull in new wire using the old wire without the need to replace or upgrade existing structures that would have otherwise been required to support larger, heavier legacy type conductors such as ACSR (Aluminum Conductor Steel Reinforced).
Advanced conductors, such as ACCC® (Aluminum Conductor Composite Core) use light-weight carbon fiber composite cores that enable the incorporation of added aluminum content without an overall increase in diameter or weight. While the composite core offers a lower coefficient of thermal expansion (compared to steel) to mitigates conductor sag and improve clearances to vegetation and underbuilt structures, the added aluminum content helps carry more current with reduced electrical line losses.
Reduced line losses help deliver more power from existing generation assets to reduce costs and, in some cases, reduce fuel consumption and associated GHG emissions. Considering that thermal power plants consume between 10,000 and 50,000 gallons of water per MWh of electricity generated, line loss reductions can also translate into reduced water consumption which may be an important consideration in drought-prone regions.
In 2016, American Electric Power upgraded two adjacent 120 circuit mile 345 kV transmission lines in the Lower Rio Grande Valley in Texas. They used advanced conductors to double the capacity of these transmission lines primarily to accommodate peak load winter demand. Reconducting with ACCC® allowed them to utilize existing structures without modification – saving tens of millions of dollars and months of time. While their primary objectives were completed successfully, line loss reductions also saved them an estimated 300,000 MWh per year (at a relatively low load factor of 34%). At that time, based on all combined sources of generation resources, that equated to a reduction of CO2 emissions of ~200,000 metric tons - the equivalent of removing over 43,000 cars from the road (one car in the U.S. emits ~4.6 metric tons of CO2 per year). They also saved an estimated 3.5 billion gallons of water per year (@12k gallons/MWh).
Over the years, many utilities offered consumer rebates to encourage the use of more efficient appliances, light bulbs and other devices - primarily to help delay the need to build additional generation resources that were very expensive and nearly impossible to permit. Today, it seems quite logical for utilities to be encouraged if not incentivized to use energy efficient advanced conductors that can not only help reduce grid congestion costs - and link cleaner generation assets - but especially for the “second and third tier” benefits that include GHG emission reductions, improved clearance to vegetation to reduce fire risks while helping utilities reach their broader sustainability goals.
Other substantial advantages to reconductoring with advanced conductors was clearly reflected in Southern California Edison’s recently completed Rector to Vestal and adjacent Vestal to Magunden 230 kV transmission reconductoring projects in the Big Creek Transmission Corridor. The use of ACCC® Conductor not only doubled the corridor’s capacity - which has huge transmission grid reliability impacts at the independent system operator level - it also saved consumers more than $85 million dollars in lieu of a project that used conventional ACSR conductors to increase line capacity and fully resolve sag infractions. Additionally, it reduced construction time from an estimated 48 months to 18 months - freeing up SCE resources and crews to focus on other projects.
The use of advanced conductors offers tremendous benefits. The ACCC® Conductor, in particular - which has been deployed to well over 1,000 projects, globally - is a well proven technology whose time has come. If you are not familiar with it, today might be a good day to take a closer look. www.ctcglobal.com