Government Study Finds Cheaper Way to Put Power Lines Underground

A new government-backed study has revealed that innovative underground cable installation techniques could dramatically cut the cost of hiding electricity transmission lines beneath the ground.

The report, commissioned by the Department for Energy Security and Net Zero (DESNZ) and produced by engineering consultancy Ramboll, examined whether newer construction methods could offer a cheaper alternative to traditional undergrounding techniques that are often criticised for their high price tag.

With opposition to new overhead pylons continuing to grow in some parts of the UK, the findings could reignite the debate over whether more power infrastructure should be placed underground.

At the centre of the study is a technique known as cable ploughing, which allows high-voltage cables to be installed directly into the ground with minimal excavation. According to Ramboll, the approach could reduce the overall cost of underground cable schemes by between 20 and 40 per cent compared with conventional "cut-and-cover" construction methods.

The savings could be even more dramatic when it comes to civil engineering costs alone, with reductions of up to 72 per cent identified in some scenarios.

Researchers assessed a range of alternative installation techniques over route lengths of 20km and 50km. These included horizontal directional drilling, microtunnelling, auger boring, Direct Pipe, E-Power Pipe and Pipe Express technologies.

While several methods showed promise, cable ploughing, horizontal directional drilling and microtunnelling emerged as the strongest contenders when compared with traditional construction techniques.

Although these technologies are already commercially available, they have largely been used on smaller projects or outside the UK, meaning widespread deployment on major transmission schemes remains relatively untested.

The report suggests there is significant scope for innovation to transform how electricity infrastructure is delivered in the future.

Supporters argue that reducing construction costs could make undergrounding a more realistic option in sensitive landscapes and areas where communities have raised concerns about the visual impact of overhead power lines.

One company already championing the technology is Welsh contractor Aneurin Thomas Plant, which has deployed specialist cable-ploughing equipment supplied by German manufacturer Foeck. The firm has promoted the technique as a less disruptive solution, particularly in environmentally sensitive locations.

Despite the potential savings, Ramboll noted that cable materials themselves still account for a substantial proportion of overall project costs. Nevertheless, the consultancy believes the findings provide valuable evidence for policymakers, network operators and developers as they consider future transmission projects.

The report arrives at a critical time for Britain's energy network. National Grid and transmission operators are preparing to deliver hundreds of miles of new infrastructure as part of plans to connect renewable energy projects and strengthen electricity supplies across the country.

Several major pylon projects have attracted fierce opposition from residents, campaign groups and local politicians, many of whom argue that more cables should be buried underground despite the higher costs involved.

Until now, the price of undergrounding has often been cited as one of the biggest barriers to wider adoption. The latest findings suggest that emerging construction methods could help narrow the gap, potentially giving planners more flexibility when assessing future routes.

The study stops short of recommending wholesale replacement of overhead lines, but it indicates that a combination of new installation techniques and advancing cable technologies could make underground solutions more viable on selected projects in the years ahead.

The research also points towards further technological breakthroughs that could drive costs down even further. Emerging innovations such as graphene-enhanced conductors and improvements in converter station design are highlighted as potential game changers for the electricity sector.