As Congress, the Department of Energy and Federal Energy Regulatory Commission move to spur new transmission, efforts are underway to improve existing transmission assets and expand where they can go.
For example, transmission developers are increasingly looking to "shared usage of right of way," negotiating directly with rail lines and governmental stakeholders of highways to use those corridors to bury transmission lines, according to Kevin Ludwig, associate vice president and grid solutions leader at Black & Veatch. There has also been a focus to use inland waterways with submarine cables which are paired with a high-voltage, direct current transmission system to move large amounts of power, Ludwig added.
In terms of existing transmission technology, high-temperature, low-sag conductors are being deployed in niche cases largely when transmission owners are seeking to push more power in a corridor or need their transmission to span a long distance but are constrained by special crossings, Ludwig said. Such conductors have a heat-resisting composite core rather than steel that's commonly used to structurally support lines, allowing more power to be pushed through the line without it expanding and sagging.
"The barrier to broader migration to high-temperature, low-sag conductors are its cost and the special tools/hardware required for installation," Ludwig said. But there are new developments in this space that allow composite conductor installation with the same tools/hardware as traditional conductors with the benefits of high-temperature operation. Separately, there are also advances in conductor monitoring technology that allow for real-time rating adjustments rather than a static rating which often is based on worst-case conditions that only exist for a small portion of a year. This technology allows additional energy flow without any investments in new conductors and will be rolled out by utilities as a result of FERC order 881 to improve transmission line ratings.
Elsewhere, Ludwig said pilot projects are underway with high-temperature superconducting power lines involving underground infrastructure cooled by liquid nitrogen, allowing transmission to have nearly zero resistance. In addition, AC transmission lines — typically governed by breakers that only allow operators to turn the lines on or off — are growing more dynamic with controls that can regulate the power flow by adjusting the line's impedance, much like using a valve to adjust water flow.
Among the companies pioneering new transmission-related technologies that help utilities, four are worth noting:
NewGrid's congestion monitoring/mitigation solutions for the grid uses "operational transmission topology optimization," said Todd Allmendinger, director of consulting and research at the Cleantech Group. This can avoid congestion and curtailments affecting renewable power plants by rerouting flow around bottlenecks. This is done by opening and closing transmission circuits, much like traffic lights in a big city.
2. Pearl Street Technologies
The company applies methods used in computer chip circuit design and simulation to grid planning, Allmendinger said. "They've developed a physical-based grid model which can run simulation and optimization scenarios for long-term planning.
Initially targeting the transmission networks in the U.S. is a smart move by the firm, given its federally regulated nature and therefore the ability to access clean data at a national scale," he said. With seed funding raised in January, the company plans to increase its portfolio of ISO customers. Allmendinger notes part of their importance to those who own and operate transmission and distribution systems: their longer-term vision is to "become a one-stop shop for planning real-time control for all distribution, transmission, and microgrid networks," he said.
Pearl automates the creation of base case planning models for customers who've grown tired of the traditional ‘hand-made' approach, which costs more in the way of staff time. Those models have been a boon to customers seeking to reduce costs and realize greater efficiencies for the planning of new investments, including transmission and other projects. But one potential downside of automating base case planning models is the problem that arises whenever low-quality data is used at the start of the process when base cases get shaped.
3. TS Conductor
The California-based company is updating existing steel-based conductor/wire transmission technologies — a segment of the grid that has changed little over more than a century.
According to founder and CEO Jason Huang, the company produces a new kind of electric conductor (used in transmission and distribution networks) which can increase the capacity of existing lines 2.5 times without having to change or retrofit the existing supporting infrastructure (e.g., poles, towers). "This allows grid operators to accept large increases of renewable power generation coming online at minimum additional cost to electricity consumers, Huang said." This becomes important as much more of these resources come online during the next few years. Thus, one benefit of TS technology is that it opens up a constrained electric grid, at the minimum cost possible, in order to allow renewable generation to make its way to customers, Hervé Touati, TS's chief strategy officer, said.
Last December, TS saw three partners — Breakthrough Energy Ventures, National Grid Partners and a subsidiary of NextEra Energy — finance its $25 million investment round. Touati is quick to point out the potential implications of their technologies for grid resiliency. At a time when demand is rising for hardware that can withstand extreme weather, TS conductors are 2.4 times stronger than their steel core equivalents, which have been used since the early 20th century for transmission and distribution networks.
Global warming results in the wires getting hotter, which means they can handle less capacity. Touati says that "TS conductors have a thermal extension that is considerably lower than the thermal expansion of steel - 193x lower to be specific. As a consequence, TS conductors are much less susceptible to sag at higher temperatures.
TS Conductor has been selected by PG&E for fire remediation. The specific technology that has been selected is TS's smart covered conductors. Touati explained that "the conductors are externally protected by insulation ("covered") and internally contain an optical fiber that operates as a sensor to detect elevated temperature or other anomalies on the line. The intended use is in the distribution network of PG&E, not the transmission network."
Larry Miloshevich, an independent advocate on issues of energy policy and energy regulation, became familiar with TS Conductor as a participant in a transmission proceeding at the state Public Utilities Commission concerning Xcel Energy's application to construct a $1.7 billion, 560-mile transmission line called Colorado's Power Pathway. The line will access high-quality renewable resources in eastern Colorado.
"I was not previously aware of carbon-core conductor as an alternative to traditional steel-core [aluminum conductor steel reinforced] ACSR transmission line, but…it quickly became clear on the basis of engineering data that [the] carbon-core conductor, and [the] TS conductor in particular, is the future of transmission lines," Miloshevich said.
"While new materials and design for transmission lines may not sound like a revolutionary application that has the potential to accelerate the renewable energy transition and reduce its cost, it is, for several reasons. The carbon core of [the] TS conductor is stronger and lighter than [the] traditional steel core conductor, and it has very low expansion and 'line sag' caused by heating when carrying higher electrical power," he continued.
"The higher strength allows the use of the most conductive but softer 'annealed' aluminum to carry the power, whereas annealed aluminum cannot be used with [the] traditional ACSR conductor because the aluminum must provide part of the strength, so harder and less conductive aluminum must be used with [the] traditional conductor," Miloshevich added.
Asked about TS, the co-founder of Rocky Mountain Institute, Amory B. Lovins, said that he'd "agreed to advise TS Conductor because its unique technology looks so important in decongesting the grid by profitably and conveniently reconductoring within existing rights-of-way. This could cut a decade off urgent transmission debottlenecking for renewable expansions — and the economics and reliability look excellent too," Lovins said.
Last December, the New York Power Authority (NYPA) announced it will deploy LineVision's non-contact LiDAR (light detection and ranging) sensors to monitor its 230kV transmission lines in Franklin and Clinton counties, both located in upstate New York. The sensors not only unlock additional capacity on the grid, their data provide insight into conductor health and support the "real-time detection of anomalies and potential risks to the transmission system," according to Jonathan Marmillo, LineVision's co-founder and vice president of product management.
Marmillo explained that "utilities are moving to more resilient and optimized grids. Especially in the age of climate change — wilder, more violent storms are a risk to transmission lines. We've seen power lines cause wildfires; we've seen them ice-up and fail. More often than not, we're seeing 70-year old lines asked to contend with modern problems not just limited to capacity challenges. And they just can't. Our sensor offers a complete picture of what's happening on lines — offering data they've never had before without simply sending a crew out to physically inspect every line 24/7. Our sensor does that for them."
According to Babak Enayati, manager, DG standards and new technology at National Grid, "LineVision's sensors are at the core of our grid enhancing technologies program because its dynamic line ratings solution enables us to increase visibility of the capacity of our electric transmission network. Over the past year of testing these sensors, we found that LineVision's monitoring system and Dynamic Line Ratings platform provides a 31% increase in capacity over ambient line ratings and a 45% increase compared to static ratings. Knowing the rating of the transmission line helps us to optimize system operations."