Engineers from National Grid, and contractors Morgan Sindall Infrastructure and Siemens Energy, have completed replacing existing cables to new high voltage electricity cables as part of its Dinorwig to Pentir project.
The first of three sets of high-voltage electricity cables connecting Dinorwig hydroelectric power station in Gwynedd to National Grid’s transmission network has been energized.
Dinorwig power station is owned and operated by First Hydro, a company that's 75% owned by ENGIE. National Grid has been upgrading the 12 km connection between its 400 kV Dinorwig substation transmitting its electricity to the grid, and its 400kV Pentir substation.
The first new circuit including three 12.2 km cables, each made from 14 sections joined together and weighing an estimated 1,500 tons, has been installed under sections of the A4086 and A4244, in nearby fields and inside Dinorwig. Each new circuit takes a different route from the original cables, ensuring the existing connection remains in service and continue transmitting clean power from Dinorwig, while the upgrades are in progress.
National Grid’s project is an essential upgrade to the transmission network to ensure the reliability and security of electricity supplies from ENGIE’s First Hydro site to the local area and beyond in the future, as demand for electricity increases. Work is under progress to complete two other new circuits as part of the scheme.
National Grid is also upgrading its Dinorwig substation. The complex engineering work is an essential part of creating the new, secure and reliable connection between the power station and the electricity network.
Additionally, National Grid is safeguarding critical bat habitats in the cable tunnels, which has included installing permanent acoustic barriers alongside roosts to reduce disruption during construction.
Dinorwig hydroelectric power station is made up of 16 km of underground tunnels deep below Elidir Fawr mountain in Gwynedd. It is a vital part of the electricity network in Wales and England, providing fast-response power generation to help stabilize demand on the transmission network.
