Explainer – Building new pylons in the UK

Before building any new parts of the electricity grid, network operators will always first consider every option to squeeze more capacity and capability out of existing grid infrastructure. If new infrastructure is needed to meet demand, network operators assess all types of infrastructure – taking in to account costs, environmental impact and the amount of energy that needs to be carried. These options typically include underground and subsea cables as well as new pylons and overhead lines.

Some commentators have questioned the cost, the impact on communities or local landscapes and the long-term viability of pylons, pointing to the experiences of other countries that they claim have moved away from pylons towards other solutions. To help inform future debates, we present some information below:

Are more pylons needed, why can’t we just update existing infrastructure?

The National Energy System Operator (NESO) have been clear in their ‘Beyond 2030’ publication which looks at the future of the grid, that the UK requires a combination of both onshore and offshore infrastructure, and a range of infrastructure solutions to achieve our goals. Pylons are one of those solutions to get us there.

Network operators always try to squeeze as much capacity out of existing infrastructure as possible, including managing peak demands and increasing network ‘flexibility’. When they have exhausted all those options, they consider the requirements for new parts of the network and where to place it. In some areas, it is possible to place new lines near the existing ones and minimise the ‘footprint’ of the grid. However, sometimes this is not possible so new sites need to be created.

Are pylons more expensive than other solutions?

No, this is not correct. Network operators have regulatory and license obligations to ensure that the cost of improving the electricity network is efficient, given that it is ultimately covered by the UK’s electricity consumers.  

The cost of offshore solutions – cables under the sea – can be significant. In East Anglia, published assessments for an equivalent offshore infrastructure solution showed that to deliver the same capacity as a proposed overhead line, you would need to build three subsea cables and six converter stations. This is because you would need one converter station at each end of the subsea cable. In total it would cost over four times that of a solution using overhead lines.

The government's electricity networks commissioner also estimated that undergrounding cables can cost up to ten times as much as going overhead, with these costs ultimately being borne by consumers. Though costs vary from project to project,  annual maintenance costs for underground cables are higher than for overhead lines, due to significant amounts of associated equipment that need to be maintained at each end and along the route. This is alongside higher costs to make any repairs which may occur throughout their lifetime, for example, repairing damaged cable joints.

But it’s not just about costs. We understand that plans for any new infrastructure can cause concern in nearby communities. It's therefore essential to balance this cost with environmental and technical factors, alongside the views of local communities, when making decisions around infrastructure. Careful consideration is given to all these areas, to help inform and shape the proposals.

Balancing these is a difficult job and there is no ‘one size fits all’ solution. The network developers' job is to carefully consider the most feasible options and present proposals for public consultation from which they will review all the feedback to help develop more detailed proposals.

Why can’t we be more like countries that have their infrastructure offshore or underground, like Germany?

There is no fully offshore solution to connect offshore wind to the grid in any country. The power must be brought onshore somewhere, and still needs to be transported to different areas of the country to power homes and businesses.

Our neighbours around the North Sea have similar plans. For example, the German Grid Development Plan 2037/2045 includes a need for substantial new onshore overhead lines and substations, in addition to subsea and underground cable proposals.

Germany’s opposition has recently said using overhead lines instead of digging underground could save the country €35 billion. German political parties which previously backed underground cables, as part of former Chancellor Angela Merkel’s grand coalition, have now called for overhead lines to be given priority.

Are pylons more damaging to the local environment?

When planning routes for overhead lines and substations, network operators consider their visual and environmental impacts and how this may affect the local scenery, heritage sites and communities. Network operators seek to reduce the visual impact, carbon emissions, waste and water usage of their infrastructure while increasing the biodiversity of their sites. They consult with local communities, agencies and landowners with the aim of finding the best solution possible.

Underground cables, including high voltage direct current (HVDC) cables, are often suggested as an alternative to pylons. Again, there is no one solution which will work for every project and underground cables are used across the electricity grid where they best meet project requirements.

However, the decision to use underground infrastructure must be rigorously tested, and other options considered, as this infrastructure can have lasting environmental effects, particularly on natural habitats and hydrology. The area required for laying cables also needs to be cleared of buildings or vegetation, for easy access during construction and repairs. On average, over 14 times as much earth is excavated for underground cables than overhead lines.