SuperNode’s superconducting cable system is specifically designed to be compatible with conventional equipment and techniques for deployment and operation. In the marine (offshore) context this includes compatibility with conventional vessels, cable handling and deployment techniques and equipment, trenching equipment, subsea rated power and control systems, and the competencies associated with the deployment and operation of this equipment. Of particular note is SuperNode’s development of novel joints for individual cable section ends, which enables the joining of multiple sections during deployment through a simple and rapid ‘plug’ operation, avoiding the need to splice superconducting cables in the field. In the onshore context the cable is designed for transport on road reels and deployment and management with conventional equipment.

Just one-third of the materials utilised in superconducting cables consist of metals obtained through primary mining activities or as mining by-products. However, these metals can all be obtained from secondary (recycled) sources. Copper is a critical metal to the energy transition and to power grids, and has seen demand and prices skyrocket. Superconducting cables require 85% less copper than conventional cables for equivalent power transmission which would shield SuperNode from copper markets. Other critical metals like Silver, Nickel and Rare earths are required in tiny quantities.

All of the other materials used in superconducting cables are non-metals and can be manufactured and therefore have a minimum supply risk. 100% of materials used in superconducting cables are recyclable when they reach their end-of-life.
Lead, which is used for corrosion resistance in conventional cables, is identified by the EU as a substance of very high concern and has been recommended to be included in Annex XIV of the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals). There is No lead (Pb) found within a Superconducting Cable. None of the materials used in superconducting cables are listed on the REACH authorisation list.

LN2 which is used to cool the superconducting tape, can be extracted out of air, which is approximately 78% Nitrogen.

The installation of SuperNode’s superconducting cable is performed similar to standard power cables, with cables transported to location on standard cable drums/reels. The cables are then placed in ducts or buried directly in the ground depending on the location and application.

Superconducting cables typically require an active control system for cooling and recirculation of liquid nitrogen. These systems are autonomous in operation and require very little maintenance throughout the operational life of the system.
Qualification of AC superconducting cables is performed in accordance with IEC 63075 ‘’ Superconducting ac power cables and their accessories for rated voltages from 6 kV to 500 kV – Test methods and requirements ‘’ and Cigre TB 538 ‘’ Recommendations for testing of superconducting cables ‘’ and Cigre TB 644 ‘’Common Characteristics and Emerging Test Techniques for High Temperature Superconducting Power Equipment ‘’.

For DC Superconducting cables there is currently no qualification standards, a combination of standards will be required, leveraging on the experience of AC superconductors and also extruded cable qualification such as IEC 62067 “Power cables with extruded insulation and their accessories for rated voltages above 150 kV (Um = 170 kV) up to 500 kV (Um = 550 kV) – Test methods and requirements’’, IEC 62895 ‘’ High voltage direct current (HVDC) power transmission – Cables with extruded insulation and their accessories for rated voltages up to 320 kV for land applications – Test methods and requirements’’ & Cigre TB852 ‘’ Recommendations for testing DC extruded cable systems for power transmission at a rated voltage up to and including 800 kV ’’ and Cigre TB

Both AC and DC Superconducting cables have advantages and disadvantages depending on the application.

For high-capacity power transmission, DC cables can be utilised over longer distances than AC cables. DC cables do not experience the same electrical losses as AC making them more efficient in power transmission. Most national grids however, operate with an AC system therefore DC transmission requires large infrastructure (Converter Stations) for the technology to be integrated with existing networks.

SuperNode are developing both AC and DC superconducting cables for a variety of different applications, AC superconducting cables for small scale power applications such as grid resilience in urban dense locations and DC superconducting cables for large-scale point to point power transmission, and meshed DC rids.

SuperNode’s cable is approximately the same physical size as conventional cables today. A key advantage of SuperNode’s superconducting cable design is its scalability. The superconducting cable can be designed to deliver significantly higher powers without any geometry change. This means that for a given geometry the cable power can be significantly increased without requiring bigger cables or increasing the number of cables for a given power transfer requirement. For example, today’s conventional state-of-the-art technology is 525kV DC cables, with the ability to typically transfer 2GW of power in a bi-pole configuration. For additional power transfer requirements (i.e. >2.0GW) the projects will require an additional pair(s) of cables. SuperNode’s superconducting cables however, can be scaled from 1 – 10GW in the same cryostat geometry.

Vacuum degradation and the associated impact on thermal insulation performance is one of the most significant challenges that SuperNode are working on. To this end we have developed bespoke test equipment for measuring insulation performance, and we are working with different collaborators within this space. The most prominent of these projects has been undertaken with CERN to understand how the novel materials SuperNode are developing interact with the vacuum over the lifetime of the cryostat. The mechanical loading on the system during its deployment and lifetime are well understood, and are a key input to the design specifications for the system.

In terms of integrating SuperNode’s High Temperature Superconductor (HTS) technology with standard power conversion and switchgear architectures and equipment, several considerations need to be addressed:

• Power Converters: To integrate HTS devices with standard power systems, power converters are used to convert the alternating current (AC) from the grid to the appropriate direct current (DC) for the HTS equipment. Conversely, when power is fed back to the grid from HTS devices, power converters are required to convert DC back to AC.
• Protection and switchgear: HTS devices need proper protection against faults and overcurrent events. Specialised switchgear that can handle high current levels and interrupt fault currents can be designed and implemented. The cables themselves can be designed as fault tolerant and inherently react with increased impedance to grid faults, firewalling and/or protecting against propagation of faults in meshed grids.
• Grid compatibility: The integration of HTS technology with existing power systems requires compatibility with the grid’s voltage levels, frequency, and control systems. This can seamlessly be accommodated as per codes and requirements.
• Scalability: HTS cable technology is ideally suited for large power applications. Multiples of power capacity can be achieved with minimal increases in cable geometry and cost, unlike conventional cables which scale proportionally in cost and size for power capacity increases.

 SuperNode, with its partners in industry and academia, is actively supporting the development of integration and protection technologies that can optimally leverage the power characteristics of its HTS cable such that compelling system-wide value proposition can be realised across high-capacity, renewables-based transmission networks.  

Firstly, it’s important to consider the similarities between a superconductor cable system (SCS) and conventional technologies. For both, the end effects of major structural damage is the same i.e. loss of electrical transmission.

Like conventional technologies, our system is designed for use in the given operational environment so the main cause of this damage would either be defects of the system during production, deployment loads beyond the specified limits or rare accidental events (including anchor strikes, digger strikes and trawler impact).

The key differences lie in what physically happens to the cable and how we address these issues. Given the design architecture of the SCS, catastrophic damage can affect several different parts, but the main system-level effect for the SCS is damage to the thermal performance, which in turn can cause sections of the system to heat up and lose superconductivity. Dependent on the extent of the damage, the SCS could continue functioning at reduced capacity until repairs are needed.

For conventional cables, most cases of damage are addressed by finding and repairing the affected section of the cable, which itself is an onerous task. A key benefit of the SCS is the embedded detection systems and its modularity. A digital twin initiative will be implemented which actively monitors the cable’s operational condition and feeds the date to predictive models that trigger control protection and maintenance actions. In the event of failure, location of any damage to the system can be established down to the one-meter section of cable where it occurred which facilitates local intervention or expedited replacement of a specific damaged cable module.

Generally these risks are low, but they are reduced even further by controlling the manufacturing processes, embedding safety within the design, and qualifying the cable beyond the basic operational conditions to ensure it remains robust throughout its operational life.

Firstly, the fault parameters are clearly defined, namely fault current and fault duration. These are determined by examining the HTS cable circuit and the operational and emergency scenarios to which it will be exposed. The maximum current the cable will experience during a fault and the fault duration are determined and form a design input to the HTS cable. A shunt made of copper is added to the cable assembly and is sized accordingly to the fault current and fault duration. During a fault, the copper shunt and high temperature superconducting (HTS) material share the fault current. The copper shunt protects the cable from damage as it has been designed to handle the fault current for the fault duration. Current limiters or a trip switch can also be used used to cut power to the cable and protect the cable such that design fault current or duration is not exceeded. SuperNode has conducted various simulations and laboratory test programs to ensure our cables can withstand any fault conditions they might encounter during their service life.

SuperNode’s superconducting cable is being put through a comprehensive qualification and demonstration program under the review of a third-party certification body. This program will subject the cable to a wide suite of tests (both industry standard and novel) which will verify the reliability and safety of SuperNode’s cable and all required ancillaries through the entire lifecycle of the system. In addition, while current generation superconductors do require active cooling, SuperNode are designing the active elements of the system with appropriate redundancy and reliability to achieve the availability required for an ultra-high-power transmission asset.

We are developing a cable technology that is more efficient than standard copper cables at long-distance, high-capacity transmission. However, the real value of our technology is the economic and operational benefits it can deliver to the transmission system as a whole; it can enable reduction of equipment & infrastructure size and cost throughout the network. Whilst the equipment that our cable integrates with is standard in nature, for some applications, new designs and configurations are required to fully exploit the beneficial characteristics of our cable. We are working closely with leading academics and industry OEMs to study and develop such substation and converter station equipment and systems. As with any integrated DC transmission system, we do require power conversion and protection equipment to operate seamlessly with our cables. We undertake detailed integrated system studies to understand the operability, constraints and requirements for such systems such that they can inform our cable design and deliver optimised system-wide techno-economic benefit.