Composite conductor cores enable power modernization - Case De Angeli Prodotti
At around 2.9 watt-hours per request, OpenAI’s ChatGPT’s more than 200 million weekly users would consume nearly 60 MWhs by searching once each week — enough to power two Glastonbury festivals. Surging electrical demand from AI-enabling data centers and increased urban power consumption, as well as vast renewable energy production, require upgraded electrical infrastructure. To help grid owners’ search for a way to maximize transmission capacity without lengthy new construction projects, electrical equipment OEM De Angeli Prodotti built a partnership with composites expert, Exel Composites.
Europe’s electrical grids urgently need an upgrade and there are several reasons behind this. With multiplying devices, growing reliance on AI tools, and the shift to electric vehicles (EVs), demand for uninterrupted power has skyrocketed. The push for renewables like solar and wind adds variability, requiring flexible grids to manage production peaks. Climate goals like the Green Deal and electrification of transport, heating, and industry further strain the system. Extreme weather and cybersecurity threats demand resilience, while cross-border energy integration exposes bottlenecks. Finally, smart grids and efficiency improvements are essential to reduce losses and adapt to evolving needs.
Although electricity consumption has fallen in successive years since the energy crisis of 2022, the German, Spanish, and French governments have all projected between 2-7 per cent compound annual growth rate (CAGR) of net electricity demand between 2023 and 2030. Additionally, the European Commission has mandated that 42.5 per cent of EU energy must come from renewables. This presents its own challenge.
Where a country might have once relied on dozens of large power generation centers, the shift towards decentralization will multiply the generation points due to smaller wind, solar, and tidal plants feeding into its grid. Around 40 per cent of European overhead power lines are over 40 years old, lacking both the capacity and flexibility to transmit the amounts of power that we now produce and use.
Scaling up power transmission infrastructure to match this need for increased capacity and integrating this multitude of sources poses a major challenge. Building new transmission lines with new towers can take between eight and ten years, and is nearly impossible in some built-up areas. Here, advanced conductor core technology is the key to making the most out of existing power infrastructure.
Composite conductor core technology helps Europe meet its power demands
Replacing the steel cores in traditional aluminum conductor steel reinforced (ACSR) conductors is the focus here. ACSR conductors have stranded conductive aluminum wires around a mechanically supportive steel core. However, at higher temperatures with increased current, this steel expands and the wires begin to sag, potentially breaking regulations on the acceptable distance from the ground.
These steel cores also conduct some electrical charge away from the aluminum, leading to energy losses during transmission. Adding additional aluminum into cabling will improve electrical capacity, but steel cores leave no room for this extra conductive material as the line is designed according to a specific conductor size.
In contrast, carbon fiber cores are known for their high tensile strength and light weight, which have earned them high-temperature, low-sag (HTLS) status. The grades of carbon fiber used in composites conductor cores have a coefficient of thermal expansion of between 0.2-0.9 x10-6 K-1 while steel tends to have 12-17 x10-6 K-1.
Conductors with carbon fiber core allow power asset owners to meet ground clearance, meaning the conductor distance -from -ground regulations even up to conductor temperatures of 190°C.
While building new transmission infrastructure takes up to a decade, reconductoring can be completed within 12-24 months. Advanced carbon fiber composite conductor cores can double the ampacity of the line, also known as the current carrying capacity, addressing immediate challenges in the energy modernization process. These include integration of recently built renewable sources and supply for essential data centers.
Finally, ESG regulations will increase the pressure on grid companies to improve their processes’ sustainability significantly in the next ten years. Eliminating most of the construction needed and reducing transmission losses during the line’s lifetime will significantly bring down associated emissions, especially with breakthroughs in sustainable carbon feedstocks and the use of renewable energy in carbon fiber manufacturing.
Breakage threatens the single-wire cores
Despite their advantages, some issues have so far dissuaded transmission system operators (TSOs) from universally adopting conductors with carbon fiber reinforced cores. Most predictably, the industry’s unfamiliarity with this solution slows down its implementation. Metal-based conductors have been used for more than a century and any technological innovation requires use cases and demonstrations of efficacy to succeed.
Another concern is that the 1st generation solution of these conductors uses a single strand core and, as these very long components can be sensitive to mishandling, there’s a risk of breaking them. This material sensitivity can lead the constructors and installation crews, more familiar with ACSR or nickel alloy-based INVAR cores, to break the carbon fiber filament while handling it.
For TSOs looking to upgrade their infrastructure swiftly without incurring huge costs, compromising the installation in this way is unacceptable. One solution that smoothed the integration of single-wire conductor cores is De Angeli Prodotti’s ACCS-Sens monitoring system. Here, the aluminum conductor composite single core (ACCS) has three optic fiber wires embedded inside to check the integrity of the core during installation.
Exel Composites collaborated with De Angeli Prodotti to provide this reassuring fix to TSOs and it has succeeded, with hundreds of kilometers delivered on one project in Belgium alone.
Even before the two companies developed the ACCS-Sens technology, an alternative was produced. De Angeli launched the aluminum conductor composite multi (ACCM) core as an intrinsically safer version to put TSO’s minds at ease.
The ACCS-Sens was not the first project on which the two companies had worked together, however. After an enormous Italian grid operator had requested a more robust solution than the ACCS core, De Angeli targeted a new design.
“Although the ACCS-Sens provides peace of mind about the integrity of the ACCS core, some grid operators prefer the security of avoiding vulnerability to breakage altogether,” explained Luca Mora, president at De Angeli Prodotti. “This is the reason that we originally partnered with Exel Composites. We needed a carbon fibe core supplier that is reliable, capable, and has enough production capacity to support the development of a new product.”
“Pultrusion is the ideal manufacturing technique for this product,” explained Heini Kloster, the newly appointed product manager for conductor cores at Exel Composites. “Because it’s a continuous process, we can produce many kilometers of uniform carbon fiber profile; the only limitation is the length of the fibers themselves. This answers to the need for large capacity production.”
Multi-wire carbon fiber cores
The ACCM core features several carbon fiber wires stranded together inside an extruded aluminum tube. Exel Composites supplies these carbon fiber strands to De Angeli Prodotti, which then strands conductive aluminum around the core. The stranded core gives the conductor much greater flexibility, close to traditional ACSR conductors, making damage during installation and other handling very unlikely.
De Angeli Prodotti produced a comparative analysis of ACCM vs ACSR cores to demonstrate the business case for its conductor core solution. Readers can find a full list of the findings here.
Over a 50 km – 380 kV triple bundle single circuit transmission line, the study yielded a 60 per cent ampacity increase and a 13.08 GWh per year reduction in losses along the line.
Across our 50 km transmission line, the ACCM core yields cost savings of €1.046 million based on line loss reductions alone. This saving would see the grid operator break even within 24 months.
Most attractive for TSOs is the assurance that comes with the ACCM core. De Angeli Prodotti has published test data, the first of its kind in the conductor core industry, that shows that breakage sustained to carbon fiber strands does not damage the other wires and has no impact on their tensile strength.
“This type of validated data has never been published in this field before, it’s a big step in facilitating the wider rollout of carbon fiber conductor cores,” explained Kloster.
The typical tensile strength of non-damaged carbon fiber strands is around 210 kN, while the minimum guaranteed value to support a power transmission conductor is 147 kN. After conducting multiple experiments, De Angeli found that the tensile strength of an ACCM core with one broken strand did not fall below 172 kN.
The Italian manufacturer’s customers are satisfied with this test data and grid companies do not require a monitoring solution as part of the installation service with the ACCM conductor.
Manufacturing solutions for the power demands of tomorrow
“Exel Composites will remain our composites supply partner because of its rich expertise in R&D and collaborative approach to advancing projects,” said Mora. “Our teams had weekly meetings and worked very closely, I was impressed by the level of customer support.”
Europe and the world require big solutions to keep the lights on at Glastonbury festival and everywhere else. Integrating the recent dramatic advances in renewable energy, reducing energy losses and carbon emissions and, crucially, increasing transmission capacity are all major concerns. Carbon fiber conductor cores can achieve all of these. De Angeli Prodotti and Exel Composites are working together to modernize global power transmission infrastructure in a sustainable, cost-effective way.
