Making Existing Transmission Infrastructure Work Harder
The electric power industry is confronting a challenge that is becoming more urgent by the month. Electricity demand is growing, large new loads can appear much faster than traditional infrastructure can be planned and built, generation projects continue to seek access to constrained transmission systems, and utilities are simultaneously being asked to improve reliability while keeping electricity affordable. America unquestionably needs new generation, new transmission lines, substations, energy storage and other grid-enhancing technologies, but as we pursue those investments, there is another question that deserves to be asked much earlier in the planning process: Are we getting everything we reasonably can from the infrastructure we already have?
This question supports the broader theme of CTC Global’s “The Capacity We Already Own” campaign, but the case for doing more with existing infrastructure extends well beyond any single technology provider. A growing body of independent research, government programs and utility experience is pointing in the same direction. The U.S. Department of Energy has identified advanced reconductoring as an important means of expanding transmission capacity while reusing existing infrastructure, reducing project costs and accelerating project schedules. Research from GridLab, Energy Innovation and the University of California, Berkeley has similarly examined advanced reconductoring as a way to substantially increase the capacity of existing transmission corridors while longer-term grid development continues.
A transmission line represents much more than conductors suspended between structures. Land and rights-of-way have been acquired, structures engineered and erected, foundations installed, access established, environmental and permitting processes completed, substations connected, and communities have already incorporated this infrastructure into their surroundings. These are enormously valuable assets. When additional capacity is needed, rebuilding or replacing all of that infrastructure should not automatically be the first option considered. In many cases, the most effective place to begin is by examining whether a better conductor can allow those same assets to accomplish substantially more.
Capacity Is More Than an Amp Rating
Advanced conductors change the performance equation because they can address several limitations simultaneously. The lightweight composite core used in ACCC® Conductor allows substantially more conductive aluminum to be incorporated into a conductor of comparable diameter and weight, while its very low coefficient of thermal expansion substantially reduces thermal sag. Those characteristics address two fundamental limitations of conventional steel-reinforced conductors: electrical resistance and sag at elevated operating temperatures.
That distinction matters because conductor performance cannot be judged simply by maximum operating temperature or a published ampacity. Increasing current increases conductor temperature, higher temperature increases resistance and electrical losses, and conventional steel-reinforced conductors experience substantially greater thermal expansion and sag. A higher amp rating therefore does not necessarily translate into an equivalent increase in useful delivered power. A transmission upgrade should ultimately be evaluated by how much power it can deliver safely and efficiently within the physical limitations of the corridor.
Efficiency belongs in this discussion as well. Every transmission conductor has resistance, and the electricity lost overcoming that resistance must be generated but never reaches the customer. Reducing conductor resistance means more of the electricity already being produced reaches its intended destination. Over decades of operation, those savings can become substantial. The capacity we already own is therefore not limited to additional amperage that can be placed on an existing corridor; some of it is the power currently being consumed by electrical losses that better conductor technology can help preserve.
Real Projects Have Already Demonstrated the Opportunity
American Electric Power’s Lower Rio Grande Valley project in Texas provides one of the clearest examples. AEP needed to substantially increase the capability of two parallel 120-mile, 345 kV transmission lines serving a rapidly growing region, while maintaining service and making maximum use of existing infrastructure. The project replaced double-bundled conventional ACSR conductor with double-bundled ACCC® Drake while retaining the existing structures and completing the work while the lines remained energized.
The result was an increase in line capacity from approximately 1,751 amps to 3,099 amps (with further reserve capacity). The project also reduced line losses by approximately 30 percent, freeing roughly 34 MW of generation capacity that otherwise would have been consumed by those losses. The project was completed ahead of schedule, avoided extensive structure replacement and ultimately received the Edison Electric Institute’s Edison Award. The important lesson extends well beyond the conductor itself: AEP extracted substantially greater capacity, efficiency and value from a transmission corridor it already owned.
Southern California Edison demonstrated the same principle under very different circumstances on its Big Creek 230 kV transmission system. SCE needed greater capacity to improve access to hydroelectric generation and grid reliability but faced significant physical constraints along the existing corridor. By reconductoring with ACCC Conductor, SCE increased line capacity from approximately 936 amps to 1,520 amps without replacing the existing structures. The ACCC Advanced Conductor also addressed sag constraints, reduced the estimated construction schedule substantially and avoided major infrastructure costs.
Different utilities, different systems and different operating conditions produced the same underlying lesson: before rebuilding the infrastructure around the conductor, determine what can be accomplished by improving the conductor itself.
From Specialized Solution to Standard Planning Tool
Government policy and independent research are increasingly recognizing this opportunity. DOE has examined advanced conductors as a means of accelerating transmission expansion, and its recent SPARK initiative places substantial emphasis on accelerated reconductoring and other advanced transmission technologies capable of increasing transfer capability and making better use of existing rights-of-way. This represents an important evolution in the transmission discussion. Advanced reconductoring is increasingly being considered not simply as a solution to unusual engineering problems, but as one of the tools available to address capacity, affordability, reliability and the speed at which grid improvements can be delivered.
None of this suggests that reconductoring eliminates the need for new transmission. It doesn’t. There will be corridors where structures need replacement, locations where entirely new transmission paths are required, and system constraints involving substations, transformers, breakers or stability limits that cannot be solved by changing the conductor. Good engineering requires evaluating the entire system. But that is precisely why advanced reconductoring should be evaluated systematically rather than reserved for exceptional circumstances.
The planning sequence matters. Before deciding an existing corridor must be rebuilt, determine what can be accomplished with a better conductor. Before deciding another right-of-way is required, determine how much additional capacity the existing right-of-way can support. Before accepting electrical losses as unavoidable, calculate what a lower-resistance conductor can save over the life of the project. And before comparing conductor solutions primarily on initial material cost, evaluate structures, foundations, permitting, construction schedules, electrical losses, maintenance and the economic value of time.
These aren’t simply arguments for a particular product. They are good engineering and good asset-management questions.
For many years, advanced conductors were frequently selected when utilities encountered unusual problems – a difficult crossing, an overloaded corridor, a clearance constraint or a project where conventional conductors simply could not meet the requirement. Today, growing electricity demand, data-center development, advanced manufacturing, generation interconnection requirements and concerns about affordability are turning yesterday’s unusual transmission challenges into increasingly common ones. At the same time, advanced conductor technology has accumulated decades of testing, installation and operating experience around the world.
Perhaps the next important evolution, therefore, isn’t technological at all. It is procedural. Advanced reconductoring should increasingly become one of the standard alternatives evaluated whenever additional transmission capacity is required – not because it will be the answer in every situation, but because failing to evaluate the capacity available from existing corridors risks overlooking one of the fastest and most economical resources available to the grid.
Building the transmission system of the future will require enormous investment, thoughtful planning, new infrastructure and continued innovation. But not every additional megawatt requires another transmission corridor. Sometimes the towers are already standing, the right-of-way already exists, the substations are already connected, the community already hosts the infrastructure, and the opportunity is quite literally hanging between the structures.
Look up before we look out.
Before we build more, let’s make sure we’re using what we already have better.
