Exploring new frontiers in energy transmission

Meeting the increasing demand for electricity…

The present high demand for electricity is being driven by consumers, by the ongoing electrification of the automotive market, and the increasing rate of industrial decarbonization. In the coming years, the road towards achieving global sustainability goals will also put significant pressure on existing electrical transmission and distribution systems.  

…while meeting global climate objectives

To keep the Paris Agreement target of limiting global warming to 1.5 °C within reach, the COP28 outcome recognized that the energy sector needs to reach net zero emissions by 2050, utilizing zero- and low-carbon fuels well before or by around mid-century.¹ Under the Inflation Reduction Act, the United States has committed to reducing emissions by 50-52% below 2005 levels by 2030.²  China is also taking steps to reduce its carbon emissions. China’s 30·60 decarbonization goal estimates the country will peak emissions by 2030 and be able to achieve net zero by 2060.3 

The scale of the task: replacing the old and preparing for the future

Increasing electricity output while also reaching greenhouse gas emission targets and continuing the transition process poses an array of challenges. There is not only the challenge of replacing the current aging electricity distribution infrastructure but also a need to increase investment in adding new infrastructure, for example, more overhead power lines and subsea cables.

Research from the IEA reveals that to fully adopt renewable energy, the world will need to double the size of existing electricity grids within the next two decades.  The IEA estimates that this will require approximately 49.7 million miles of new and rebuilt transmission lines.⁵ In the US alone the required number of conductors is expected to multiply by up to 414% by 2035.⁶  To complete the energy transition, the European Union must double or even triple its energy transmission rate. To do so requires replacing inefficient conductor technology.⁷ 

True sustainability, energy security, grid stability, and optimum efficiency can only be achieved by adopting innovative new conductor technologies. This is true for both the overhead conductor market, land cables, and the subsea power transmission industry.

Sustainable overhead power transmission faces multiple challenges essential to grid efficiency and resilience:

• Resistive Power Losses
• Sag and Thermal Inefficiencies
• Intermittency in Renewable Energy Supply
• Aging Infrastructure

Luckily, solutions exist to ensure a smooth transition and prepare the network for tomorrow.

Reducing the line’s resistance with more aluminium                 

Outdated overhead cabling results in significant losses due to heat resistance. Conductors that “run hot” are extremely inefficient. Over long distances, this can greatly diminish the reliability and efficiency of the transmission cables and increase the carbon footprint of transmitting electricity. Reconductoring with higher performance conductors, that operate efficiently at higher temperatures, can help to solve this.[i]

The conductor can be made more efficient while using Mega and Giga high tensile strength steel wire cores as, for a given conductor diameter, the steel section can be reduced and the aluminium section can be increased.

Addressing the sag

Traditional overhead conductors are limited in their maximum operating temperature and have a higher thermal sag compared to advanced steel cores. Thermal sag can sometimes require maintenance which adds to the lifetime costs of the transmission line.

Sag occurs when a conductor either heats up (thermal sag) or becomes covered in ice (ballast sag). Sag clearances are calculated during line design with this in mind. Advanced conductors like composite core conductors are the most susceptible to ballast sag. Steel core conductors are the best solution for ballast sag issues due to their higher modulus of elasticity, nearly double that of carbon fiber. Our studies have shown that reconductoring with advanced steel cores is the most cost-effective option that delivers optimal capacity and efficiency while still meeting the maximum sag requirements.

Getting rid of inefficient and non-sustainable products

Existing grid conductor technology, particularly in developing countries, is not designed to cope with increasingly higher loads or the integration of certain renewable electricity sources (wind and solar) that have a more intermittent supply than sources such as coal, gas, or nuclear power.

Transforming the overhead conductor market is no easy task. There are a range of challenges including long project lead times, difficulty in obtaining approvals for new projects, and permitting process delays.

In the US, low-cost, non-sustainable imported traditional conductors are preventing newer more efficient, and sustainable options from gaining ground in the market. While less expensive, imported conductors often contain steel derived predominantly from iron ore and are manufactured using carbon intensive blast furnace / basic oxygen furnace routings, more sustainable alternatives contain recycled steel and are manufactured using highly efficient electric arc furnaces. This is the case with the vast majority of US manufactured conductors.

Likewise, Europe is also having difficulties in finding affordable solutions to efficiently transmit electricity. It has been estimated that by 2030, 40% to 55% of Europe’s low-voltage lines will be reaching the end of their lifespan and becoming increasingly inefficient.⁸ As it stands now, the European energy network will be unable to cope with the projected rise in electricity demand.⁹

Reconductoring: the only solution to move ahead quickly and sustainably

Reconductoring is often the only viable way forward. Existing power infrastructure and permits can be reused to reduce the requirement for additional new infrastructure. This removes project delays associated with obtaining permits. Reconductoring utilizes existing rights-of-way and towers and can incorporate existing components, all of which save time and money. According to Idaho National Laboratory Advanced Conductor Scan Report, using an ACSS/TW/MA5/E3X conductor can more than double the capacity with the same diameter conductor.[ii]

Achieving sustainability and controlling costs also requires more resistant, durable conductors that can stand up to extreme weather conditions and provide peace of mind during installation and in service.

Wim Van Haver: “Our Mega and Giga advanced cores for overhead conductors can be used effectively for HTLS (High Temperature Low Sag) conductors. These cores are more resistant to frost and heavy snow loads and are less critical in terms of bending radius due to their high tensile strength and high elastic modulus. They comply with existing fittings and wedges and have excellent recyclability.” 

Steel core conductors are 100% recyclable at end-of-life whereas composite cores are not. In the US, 100% of the steel used to make the steel core is used with recycled steel.

Reshaping the transmission landscape requires partnerships between forward-looking companies. Companies that are dedicated to pushing the boundaries of what is possible and expanding the capacity for innovation.

 “It is essential to work in close partnership with all the industry players to keep on looking for the best solutions for our customers to cope with the challenges of grid capacity and sustainability. At Bekaert, we can leverage our 140 years of history in innovation, backed with cutting-edge R&D and testing centers.”

[i] High Temperature Low Sag HTLS conductors like ACSS/TW/MA5 operate at much higher temperatures than the current ACSR conductors (250°C vs. 100°C).

[ii] Replacing an existing traditional Aluminium Conductor Steel Reinforced (ACSR) conductor transmission line with an Aluminium Conductor Steel Supported/Trapezoidal Wire (ACSS/TW) advanced conductor can increase capacity by 218%.¹⁰

The offshore industry’s unique challenges

The offshore industry is facing its own specific challenges, relating to subsea power transmission.

The harsh underwater environment makes the installation of subsea cables a complicated and costly process. Subsea cables must be heavily armoured to withstand damage from the installation process, trailing nets, anchor strikes, and environmental conditions in order to deliver a reliable, constant transmission of electricity.

Additionally, meeting sustainability goals in these conditions also means that it is essential to have cabling solutions that have the least impact on fragile marine environments and can reduce the carbon footprint of a project over its entire lifetime.

Cutting losses while caring better for the marine environment

To protect High Voltage Alternating Current (HVAC) electrical cables, the Bezinox® non-magnetic galvanized stainless steel wire provides more durable armouring than existing non-galvanized stainless steel, proven by long-term test data in natural sea water. The efficiency of this wire allows transmission system operators and owners to transmit energy with minimal losses and with the lowest operational costs while offering peace of mind due to its vastly improved corrosion behavior.

“Our R&D teams have long sought after a way to address these different issues posed in subsea HVAC power transmission. And came up with our Bezinox® product as a solution” Van Haver explains. “Its optimized properties prevent failures and energy losses, increased corrosion resistance offers longer lifetime, the use of more sustainable non-magnetic steel lowers the total carbon footprint. And, finally, the reduced surrounding temperature of the cable offers a better protection to the marine environment.”

Allowing deep-sea power transmission

Another essential problem faced by the offshore industry is enabling power transmission in deep water. Only until recently, offshore power cables have been applied in water depths more than 2000 meters. Standard steel products cannot meet the strength requirements associated with extreme deep sea cable laying, and other alternative materials are unproven or cost prohibitive. However, new technologies are reshaping the possibilities for deep-sea grid interconnectors.

High-performing materials that are durable, lean, and sustainable are essential to harnessing the massive potential of wind and solar and efficiently and effectively distributing power. Despite the urgent need to expand the current electricity transmission networks everywhere around the globe to meet the upcoming power demand, coupled with the pressure to improve the sustainability of the grid, solutions are available to the electrical industry to transform outdated distribution and transmission systems and develop the energy solutions of tomorrow.

The industry needs to adopt a long-term vision, where durability, efficiency, and lowering overall CO₂ emissions matter more than short term monetary gains. The key resides in closely working together with the manufacturers to find and select the right conductors to solve the specific issues of a given environment.

Additionally, steel core manufacturers like Bekaert need to continue to invest in R&D to anticipate and tackle the challenges ahead.

Wim Van Haver: “Our extensive knowledge in materials science allows us to understand which materials have the specific properties best suited to solving current and future challenges. In close collaboration with our suppliers and customers, we are creating products to tackle challenges such as improving performance, reducing energy loss, and minimizing the impact on biodiversity.”