Climate change has arguably impacted the electric power and energy industry harder than it has impacted any other. While superstorms continue to hammer Utilities in the Southern and Eastern United States, hot, dry, windy conditions AND SAGGING TRANSMISSION LINES in the Western Unites States are causing fires that have burned millions of acres, leveled thousands of homes, killed hundreds of people and cost tens of billions of dollars.
While demand for electricity is expected to increase by at least fifty percent by midcentury, and utilities are struggling to connect new sources of renewable generation, the electric transmission grid is in need of major upgrades. With that said, legacy steel reinforced aluminum conductors in use today (ACSR) are overloaded, sagging and have been attributed to dozens of wildfires on both transmission and distribution lines. While efforts continue to underground distribution lines and install better monitoring equipment, sagging transmission conductors pose a fire risk too serious and fierce to ignore any longer.
Not only do transmission lines cause fires, fires can also destroy transmission lines. Using modern high-capacity, low-sag conductors such as ACCC® Conductor, these risks can be substantially mitigated, and the grid can be prepared to efficiently deliver more power to accommodate growing demand and access new generation resources. Higher capacity conductors with corresponding substation updates can also allow grid operators to reroute power around high-risk or active fire zones to minimize the need for preemptive outages that impact people’s lives, businesses, and the economy.
Modern conductors, such as the ACCC®, use carbon fiber composite cores that enable them to carry twice the current of legacy conductors without exhibiting excessive sag. Increasing the distance to vegetation and underbuilt structures substantially decreases the risk of wildfires. Increasing the clearance to ground (with reduced conductor sag) also substantially reduces potential damage to conductors in an active fire. Unlike steel reinforced ACSR conductors, composite core ACCC® Conductors can tolerate exposure to high temperatures which helps them survive and remain in service. In most instances, legacy ACSR conductors require immediate replacement even if they don’t fall completely to the ground, because the strength of their aluminum is severely impacted and the galvanic barrier on their steel core wires is essentially lost.
While the thought of upgrading numerous transmission lines in highly fire prone areas may seem daunting, the reality is that this is being done around the world, efficiently and effectively. ACCC® Conductors, for instance, can be installed on existing transmission structures under maintenance rules without the need for excessive permitting or structure reinforcement or replacement that can quadruple project costs, installation timeframes and environmental impact.
Project Example:
In 2019 Southern California Edison used high-capacity, low-sag ACCC® Conductor to increase line capacity and resolve sag violations on their double-circuit 230-kV Rector to Vestal lines and the adjacent 230-kV Vestal to Magunden lines in the Big Creek Transmission Corridor. Implementing the ACCC® Conductors saved customers more than US$85 million dollars in lieu of a project that uses conventional ACSR conductors to increase line capacity and fully resolve sag infractions.
Reconductoring with the ACCC® Conductor also reduced the construction time from an estimated 48 months to 18 months — freeing up SCE resources and crews to focus on other projects. This reconductor project increased line capacity from 936 amps to 1,520 amps, which has huge transmission grid reliability impacts at the independent system operator level.