For most materials the critical temperature is extremely low, close to absolute zero (-273°C). High Temperature Superconductors (HTS) have critical temperature of circa -200°C and were discovered in the 1980s. For superconductors to be efficient, reliable and sustainable, cooling that can maintain the superconductor within a temperature range below their critical temperature is key. The first generation of superconducting electricity cables have been applied in urban settings to relieve congestion for 20 years. To date the technology has not been optimised for longer distance transmission or marine use cases.
SuperNode is developing the next generation of superconducting cable technology to extend the range of applications and address the limitations of first generation. SuperNode employ novel materials and thermal management techniques to maintain the superconducting wire below its critical temperature over longer distances efficiently and reliably.
SuperNode’s unique contribution is in developing innovative technology and manufacturing know how and combining it with mature superconducting wire technology to produce high capacity electrical cables. This will enable the transfer of very large amounts (several GWs in a single cable) of renewable electricity to consumers and indeed around the continent - to decarbonise Europe’s entire energy system.
Conventional cables vs. superconductors
The electrical losses of conventional cables generate heat which limits the amount of current and ergo power they can transfer[1]. Superconducting cables have no electrical losses so are not current limited. They can convey several GWs of power in a much smaller space than conventional aluminium or copper-based cables and require less infrastructure, materials, and environmental impacts.
Overhead powerline development on land is increasingly difficult as public acceptance is low. This is reflected in the PCI[2] list where overhead projects get stuck for up to 20 years and thus new ones are not even contemplated.
Conventional underground copper or aluminium cables can only carry 1 GW per cable. They suffer from electrical losses and require large amounts of material, not least in the form of copper or aluminium. As the current is limited for these conventional cables, ever higher voltages are required which drives the size and cost of the associated infrastructure. Ultimately more cables, with the associated landfalls, crossings and rights-of way, are required per unit of energy transferred than is the case were superconductors used.
The consenting process for smaller underground infrastructure is often simpler and quicker than for overhead lines so networks can be extended or supersized more rapidly to support electrification powered by renewables. SuperNode technology is much more sustainable in terms of sourcing and recycling than conventional cables where copper availability and pricing is an issue. Some copper is needed for fault scenarios for superconducting cables. For reference, SuperNode’s technology requires 85% less copper than conventional cables for equivalent power transmission.
Next generation Supernode cables vs existing superconducting cables
Superconducting electricity cables are not a new technology. They are already in use for AC power distribution to address urban congestion where space is at a premium, typically using liquid nitrogen to cool the superconductors. The first generation of the technology has used corrugated steel pipes to convey the liquid nitrogen and house the superconducting wire.
All these projects, while successful and laudable, have one obvious limitation – distance. Existing superconductor cables are limited to circa 10km between cooling stations. This limits their technoeconomic range.
SuperNode has developed a smooth-bore inner cryostat that enables vastly reduced friction, turbulence and pressure loss compared to current state-of-the-art. Coupled with innovative thermal management the cable range can be extended to 100km plus. The superconducting cable system has been designed to be manufacturable at scale, deployable, operable reliably and maintained for >40 year lifetime.
This next generation superconducting cable technology will result in lower operational and capital costs, providing a much more competitive proposition than first generation cables for long range transmission.
Technology development
SuperNode has been developing its technology since 2019 and is now commencing TRL5 (Technology Readiness Level) testing with a robust plan to TRL6 by 2025.
The Journey from TRL6 to TRL8 will require pilot projects to further qualify and prove the technology in both terrestrial and marine settings in co-operation with system operators and/or developers.
Integration of the cable systems into new and existing grids in terms of compatibility, reliability, maintenance, protection, and asset lifetime has been a major workstream for SuperNode with academia and industry.
Pilot projects are needed to prove the technology and ideally to solve a network or industrial problem to demonstrate the reliability of conventional cables. Developers and DSOs have identified opportunities in this regard and need support to take well informed and considered innovative steps. SuperNode has identified potential pilot applications for renewable connections, distribution grids, battery storage facilities, data centres, electrolysis facilities and other industrial uses where a large DC load exists.
SuperNode is developing a pipeline of candidate pilots with key stakeholders in European countries.
A key attribute of the technology is that it is scalable from MWs to GWs. The superconducting cable system that delivers as little as 50MW can deliver larger scale solutions with higher power transfers, without significant modification to the superconducting cable system. The technology is scalable to meet growing needs.
SuperNode’s aim is to provide unobtrusive efficient bulk power solutions for grids at a time when the demands placed upon grids is growing beyond what the existing solution set (toolbox and supply chain) can deliver.
