To help the world transition from fossil fuels to clean energy, a lot of work is being done on the electricity delivery system. From the distribution grid to the bulk transmission system, modernization of the electricity grid is needed. Around the world, installation of new transmission lines, renovation of distribution lines, and expansion of the overall system capacity are being proposed. Exacerbating these challenges is the growing demand for electricity around the world, but the most serious problem is the bulk transmission system with an aging electricity grid.
When it comes to aging infrastructure, the electricity delivery system is leading the way. It has been identified as a prime target for overhauling and strengthening. Last year, the IEA (International Energy Agency) released a report titled “Power Grids and the Secure Energy Transition,” which shocked readers by stating that more than 50 million miles (80 million km) of transmission lines will need to be added or upgraded by 2040 to meet decarbonization goals. The IEA report further stated, “This is equivalent to the entire existing global electricity grid.”
Just thinking about building and retrofitting thousands of miles is a huge responsibility. The IEA study is not the only notable recent report on the need to improve the robustness of the world’s bulk transmission system. Each study has a slightly different approach, but the conclusions are broadly similar: something needs to be done for the entire bulk transmission system, and it needs to happen fast. The IEA’s 2040 target has been met with skepticism from utilities, ISOs (independent system operators), and RTOs (regional transmission organizations) alike.
They understand that one large high-voltage transmission project can take more than a decade to build. Imagine the impact that having multiple large transmission projects going on at the same time around the world could have on the industry. The supply chain challenges alone, not to mention the costs, would be insurmountable. Wouldn’t it be great if we had the technology to increase transmission capacity and modernize our transmission infrastructure at the same time?
Transfer Capability
Yes, thanks to advances in wire technology, it is possible. Modern wires have been developed to achieve the highest power capacity with the lowest deflection and highest tensile strength. This is called advanced wire technology, but it spans many applications. The area of most interest in this discussion is the overhead wire segment. These are of interest to the electric power distribution industry in both new construction and re-energization projects. Since speed is the primary consideration, let’s focus on the re-energization of existing transmission lines as the primary concern.
A few months ago, FERC (Federal Energy Regulatory Commission) issued Order 1920, “Building the Future Through Electric Regional Transmission Planning and Cost Allocation.” Order 1920 addresses many of the key issues that impact the electric grid. Essentially, Order 1920, which is approximately 1,300 pages long, addresses what FERC has described as deficiencies in the existing process for planning, building and paying for current and future needed electric transmission facilities.
One of the most interesting reforms is alternative transmission technologies. Providers will have to consider these technologies when evaluating new regional transmission facilities or upgrades to existing facilities. Providers are defined as ISOs, RTOs, and utilities that are not part of an ISO or RTO. Providers have even been told they will have to explain why these technologies were or were not incorporated into their selected transmission facilities.
Modern Materials Science
The upgrades mentioned in Order 1920 also include the rewiring of existing transmission lines. Logically, advanced conductors should be the go-to technology when it comes to upgrading electric transmission facilities. Modern advanced conductors leverage the latest technological innovations to increase the amount of power that can be sent to market. According to FERC, advanced conductors include, but are not limited to, “superconducting cables, advanced composite conductors, advanced iron cores, high temperature low deflection conductors, fiber optic temperature sensing conductors, and advanced overhead conductors.”
Let’s focus this discussion on advanced overhead conductors so we can take a closer look at this wire technology. A recent study done by the Idaho National Laboratory (INL) is a great place to start. The study is titled “Advanced Conductor Scan Report” and is available on the INL website for those interested.
Examining the INL report revealed some interesting details about these innovative wires: Many of the advanced conductors INL listed should be familiar to readers, such as ACSR (aluminum conductor steel reinforced), AAC (all-aluminum conductor), ACSS/TW (aluminum conductor steel supported), and AAAC (all-aluminum alloy conductor), but they are open to debate.
Some experts argue that these conductors are nothing more than improved overhead conductors. Others say that modern material science is simply improving on modern conductors. FERC puts it nicely, “Advanced conductors include current and future transmission line technologies that have power-flow capacities that exceed the power-flow capacities of conventional aluminum conductors and steel-reinforced conductors,” and that seems about right.
Dynamic Technologies
The INL report states, “A key feature of advanced conductors is their ability to withstand the high conductor temperatures encountered during heavy loads without excessive thermal deflection.” It also notes that conductor re-strengthening can upgrade a line’s performance much more quickly, at a much lower cost, and with less disruption to the community, than new construction. This is a good place to get an expert opinion on advanced conductors and all that derives from this technology lineage. Charging Ahead reached out to Daniel Berkowitz, Strategic Market Manager at Bekaert, to discuss this complex subject and get his perspective on advanced conductor technology and how well-known conductors such as ACSR fit into the scheme of things.
Berkowitz began the discussion by saying, “As you know, ACSR is a very general term. Traditional ACSR/GA2 conductors are conductors with a standard zinc-coated strength grade 2 steel core. They come in a variety of sizes, are inexpensive and robust. This is what the grid is typically equipped with. The advanced steel cores we are developing can of course be used for either ACSR or ACSS conductors. However, conductor manufacturers are trending towards using Bezinal (95% zinc, 5% aluminum) coatings with strength grade 5 steel cores (sometimes called “ultra”) for their ACSS/TW/MA5 conductors. In Europe, we are already using even stronger cores such as strength grades 7 and 8 (“mega” and “giga” respectively). These strengths are achieved in part by adding carbon content to the steel, which increases the rated breaking strength of the conductor and allows utilities to string the conductors at higher tensions.”
Berkowitz explains: “One of the goals of the government’s transmission infrastructure modernization program is to add about 100,000 miles (160,935 km) over the next decade or so. This is an extremely ambitious goal, given regulatory and permitting issues, right-of-way acquisition, supply chain issues, and so on. But rerouting existing transmission lines with advanced conductors can eliminate or reduce these concerns. Rerouting utilizes existing rights-of-way and towers, and can also use most of the other existing components, saving both time and money.”
Berkowitz adds, “Studies have been done to replace similar conventional conductors used in existing transmission lines with a variety of advanced conductors, with very positive results. As an example, we compared the replacement of an existing conventional ACSR conductor transmission line with an ACSS/TW (Editor’s note – Trapezoidal Wire) advanced conductor. The ACSS/TW had a higher strength grade and an advanced metal coating. The diameter was the same as the original conductor. Results showed that the re-conductorized line had improved performance and a 218% increase in capacity. Tomorrow’s grid must be more efficient than today’s system. Advanced conductors are one of the most cost-effective and efficient tools in a utility’s toolbox.”
Holistic approach
There’s an old folk tale about how to eat an elephant. One bite at a time. This approach is essential to adding or upgrading 50 million miles (80 km) of transmission lines. Yes, building new lines takes time and money, but it’s necessary. But what about our congested existing lines? These also need to be addressed, as there are limits to just building new lines. Why not take a holistic approach?
In addition to new power lines, rewiring of existing lines should also be included. This not only reduces congestion but also makes it more cost-effective. High-performance, advanced conductors like the ACSS/TW discussed in the example above have increased the capacity of existing lines by 218%, the equivalent of two lines in one right-of-way. In most cases, rewiring costs less than one-third the cost of new line construction and is typically completed in months instead of years. When dynamic line rating technology is added, capacity increases by 30% to 40%. Wire technology is a win-win for both the distribution and transmission grids, providers and customers.
