DESNZ underground cable report: cost and method insights for UK grid engineers
Reviewed by Joe Ashwell
First reported on The Construction Index
30 Second Briefing
Ramboll’s DESNZ-commissioned study on undergrounding high-voltage transmission lines finds that cable ploughing, horizontal directional drilling and microtunnelling (pipe jacking) can approach the costs of conventional cut-and-cover over 20–50 km routes. Cable ploughing, already used in Wales by Aneurin Thomas Plant with Foeck equipment in sensitive environments, could cut total project costs by 20–40%, with civil works alone reduced by up to 66–72%. The report points to further savings from emerging technologies, including graphene-enhanced conductors and improved converter station design.
Technical Brief
- Ramboll benchmarked cut-and-cover against seven trenchless methods: ploughing, HDD, microtunnelling, auger boring, Direct Pipe, E-Power Pipe and Pipe Express.
- Assessment horizon focused on 20 km and 50 km transmission routes, targeting long-distance undergrounding economics.
- Methodology combined a literature review with qualitative scoring against capital cost, technical feasibility, environmental impact and completeness of solution.
- Evidence base relied on published performance and cost claims for both construction methodologies and associated cable technologies.
- Cable ploughing, HDD and microtunnelling were identified as the only alternatives with route-length cost profiles comparable to cut-and-cover.
- Application example: Aneurin Thomas Plant has deployed Foeck cable ploughing equipment in environmentally sensitive Welsh sites.
- Scope is limited by reliance on secondary data and by current UK experience largely confined to short sections.
Our Take
DESNZ’s involvement here lines up with other UK energy security work in our database, such as its Wylfa nuclear and gas storage/FSRU assessments, signalling that underground cable cost reductions could directly influence grid-connection strategies for future large generation and storage schemes.
The 20–50km study route lengths and 20–40% overall cost reductions suggest cable ploughing could materially change the business case for medium-distance onshore transmission reinforcements in the UK, especially where visual impact concerns are pushing projects away from overhead lines.
Civil engineering cost cuts of 66–72% are significant enough that UK infrastructure clients already working with Ramboll on highways and water quality schemes may start to view ploughed undergrounding as a standard option in multi-utility corridors, rather than a niche technique.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
Related Articles
Related Industries & Products
Construction
Quality control software for construction companies with material testing, batch tracking, and compliance management.
Tunnelling
Specialised solutions for tunnelling projects including grout mix design, hydrogeological analysis, and quality control.
QCDB-io
Comprehensive quality control database for manufacturing, tunnelling, and civil construction with UCS testing, PSD analysis, and grout mix design management.