The was designed to identify potential cost savings over routes of 20km and 50km. New emerging undergrounding methods were identified, and a literature review was performed to qualitatively assess these methods against key criteria, including capital cost, technical feasibility, minimising environmental impact and whether it can deliver a complete solution. The literature has identified information and claims about the undergrounding methodologies and the impacts of the cable technologies on these methods.
The assessment compared cut-and-cover as a baseline versus cable ploughing, horizontal directional drilling (HDD), microtunnelling (pipe jacking), auger boring, Direct Pipe, E-Power Pipe and Pipe Express.
The assessment identified cable ploughing, HDD and microtunnelling (pipe jacking) as having the most potential to have costs approaching those of cut-and-cover, and whilst these methods are already commercially available, they have to date been limited to short distances or applications largely outside the UK.
In Wales, Aneurin Thomas Plant has used cable ploughing equipment from German manufacturer Foeck, citing its benefits in sensitive environments.
Ramboll said its analysis shows there are significant opportunities to reduce the cost of undergrounding electricity transmission infrastructure through innovation and alternative construction methods.
The consultancy explained that cable ploughing could reduce the overall cost of underground cable projects by between 20 and 40 per cent compared with traditional cut-and-cover methods, depending on project-specific factors. The civil engineering element alone could see cost reductions of up to 66 to 72 per cent.
While cable materials remain a significant proportion of overall project costs, Ramboll says this research provides important evidence to help policymakers, network operators and industry make more informed decisions about when and how undergrounding can be delivered.
Looking ahead, Ramboll says, further innovation, including new cable technologies such as graphene-enhanced conductors and advances in converter station design, has the potential to drive further efficiencies.