BE24221 - Research Study of the Potential for Cost Reduction in Undergrounding Transmission Lines over Long Distances

The objectives are:

• To list undergrounding methods that could be used for transmission lines.
• To qualitatively assess all methods of undergrounding with respect to their suitability for undergrounding transmission lines over long distances of order 20-50km and shortlist three methods with the most potential for further study.
• To document published evidence for the lifetime cost of the counterfactual of undergrounding in shallow trenches using 'cut-and-cover' and sensitivity to distance per km in a UK context.
• To engage with specialist suppliers for the three shortlisted undergrounding methods chosen for further study to quantify and validate current installation costs and sensitivity to distance of these methods using a basis consistent with that for the counterfactual.
• To work with specialist suppliers to identify areas where innovations in shortlisted undergrounding methods such as in equipment or methodology might help to reduce costs when scaling-up to longer distances.
• To analyse and compare costs with the counterfactual and identify the main cost components.
• To identify if choices about cable technology such as voltage and whether AC or DC impacts the comparative costs of undergrounding methods.
• To qualitatively assess wider aspects of the shortlisted non-traditional undergrounding methods including constraints, environmental impact, deliverability, and energy security
• To write a final study report collating the above research and analysis with conclusions on whether there is scope to reduce undergrounding costs using nontraditional undergrounding methods and recommendations for further work