Summary: This Discovery Phase project, led by National Grid Electricity Transmission (NGET), will develop an understanding of the barriers, opportunities, and benefits of modernising existing electricity infrastructure by replacing conventional cables with High Temperature Superconductor (HTS) cables.
This will help meet the anticipated increase in demand for electricity, especially in highly populated urban areas, that will result from a shift towards electrification for heat and transport. The project will aim at investigating and developing a technology that will allow more rapid progress to be made towards decarbonisation whilst minimising costs and disruption to local consumers.
Scope: Our project will investigate a number of key questions:
- Evaluation of the costs and benefits of using HTS cabling for urban electricity networks for consumers and stakeholders.
- Modelling the impact on other parts of the network infrastructure, such as potential replacement of existing high voltage substations with a medium voltage (MV) option.
- Assessing the benefits and technical issues of using HTS technology to provide additional capacity for 132kV applications. As a 132kV HTS system has higher capacity than a 400kV conventional option, these applications cover the majority of power delivery requirements in future cities.
- Opportunity to develop standardised designs and installation techniques for HTS technology to address current high installation costs. Standardisation is one of the most effective ways in helping network operators deliver power where it is needed in the most efficient way.
Results: The key results for the Discovery Phase would be a detailed suite of reports, and a technology roadmap identifying key opportunities, barriers, and further work required to mainstream HTS cabling solutions.
Problem Bring Solved
Policy Context: The Government’s Energy White Paper (2020) and Net Zero Strategy (2021) make it clear that achieving the UK’s net-zero ambition will require the widescale electrification of heat and transport. This will mean substantially increased demand for electricity by 2050, particularly in more densely populated urban environments.
The Infrastructure Challenge: Currently the primary policy focus is on the generation of clean electricity to meet this anticipated increase in demand. However, equally as important will be the network infrastructure required to ensure that demand can be met. Without developing new infrastructure solutions, there will potentially be challenges connecting consumers to a supply of cleaner electricity.
Problem: Much of the existing electricity network was developed 40-50 years ago. This means it is an ageing technology which may not be able to deal with the level of capacity that electrification of heat and transport will demand. There are a number of key challenges:
- Cost and time: Conventional reinforcement methods for urban electricity networks are often very costly and time-consuming due to the extensive civil engineering required and the land use permits and cost.
- Capacity: To accommodate fast charging of electric vehicles, conventional reinforcement may not be able to deliver the required capacity and speed of change expected by consumers and stakeholders.
- Efficiency: Current cabling solutions have relatively high-resistance, leading to energy losses which ultimately require higher-levels of generation.
- Environmental: The thermal footprint of conventional cables and their emission of electromagnetic fields (EMFs) can impact on surrounding infrastructure and nature along the cable route.
Opportunity: We know that upgrading the electricity network infrastructure will be required to increase capacity. This creates an opportunity to investigate new, emerging technologies that are able to reduce disruption, costs, and time, and which can more efficiently deliver the capacity that heating and transport electrification will demand.
Our Solution: This Discovery Phase project will investigate the feasibility of use of High Temperature Superconductor (HTS) cable technology to increase network capacity in the urban environment. Superconducting cables have three to ten times higher power density than conventional cable systems, meaning they deliver higher capacity at lower voltage levels and via a lower number of routes. Lower voltage substations have smaller footprint, which is very beneficial for densely populated areas. HTS technology will allow faster network capacity increase, delivering time, cost, and carbon savings with reduced energy losses and wider environmental benefits.
Impacts and benefits
The discovery phase has delivered a comprehensive overview of the current status of HTS technology and the potential applications for it that exist in the GB grid.
A cost/benefit analysis (CBA) has been developed for the option to replace a 400 kV conventional system with a 132kV HTS solution. It has been populated with publicly available data and data from project partners to provide a baseline cost for comparison with actual site data that will be generated in future phases. The graph below shows the estimated through life cost of an HTS systems and a conventional system. This shows that whilst HTS systems are currently more expensive than the equivalent UGC, the costs are of a comparable order. Future opportunities such as technology learning rates, economies of scale and contractor familiarity have the potential to reduce HTS costs to achieve parity. Project costs are sensitive to the actual location, so identifying a suitable site on the GB grid for the application of HTS technology will allow costings to be refined.
As is common during investigations of lower maturity technologies, the data gathering exercise that supported our CBA identified several areas of uncertainty regarding the through-life costs of constructing, maintaining and operating HTS lines and their auxiliary sub-systems. The total through life cost will be highly sensitive to these uncertainties so at this stage it is not possible to define an accurate through life cost for the technology or to compare it to conventional technology. As an example, a significant percentage of the cost of an HTS system is the supporting auxiliary sub-systems, including the cooling systems. The through life maintenance and/or replacement frequency (and therefore costs) for the cooling system are unknown at this stage. Once known, this data has the potential to have a significant impact on the total through life cost. The graph below shows how the through life cost of the HTS system reduces as the lifetime of the supporting systems increases. This graph also shows that it is reasonably foreseeable for the through-life cost of the HTS system to achieve parity with a conventional system but this depends on a number of currently unknown factors such as the lifespan of the auxiliary systems.
One aspect of the project that has changed from the initial proposal is the detail of the case studies we wish to undertake. This change is detailed in Section 1 of this report.
