A 450 MW AI data center planned for North Wales meets opposition. At this scale, the power connection shapes the whole site

What is proposed

Gwelyfenai has submitted an outline planning application to Gwynedd Council for a data-center campus of about 300,000 square meters on the former Ferodo factory site at Griffith’s Crossing, between Caernarfon and Y Felinheli. The existing buildings would be demolished.

• Power from the transmission grid. The campus would connect to the national transmission system by underground cable from the Pentir substation, with no new overhead lines, and would not draw operating power from the local distribution network.
• Generators and a substation on site. The plans include 147 generators and a substation.
• Closed-loop cooling. The developer says water would be recirculated and none would be taken from the Menai Strait.
• Jobs. The developer estimates about 200 permanent jobs, and about 915 jobs a year for Welsh residents over a six-year build.

Why it is contested

About 300 people marched in Caernarfon on October 10. Opponents, including Plaid Cymru MP Liz Saville Roberts, question the impact on the landscape and wildlife and whether the permanent jobs justify a site of this size. The Welsh Government is now considering a request to take the decision from Gwynedd Council. It has not said whether it will.

The wider picture in Wales

South Wales is a UK AI Growth Zone. In August, Nebius made the first commercial commitment there, leasing AI capacity at Vantage’s Newport campus; Vantage expects more than 1 GW of AI-ready capacity across Newport, Bridgend and Bro Tathan.

What large sites have in common

• One very large connection. A campus of hundreds of megawatts is planned around a single transmission connection, its substations and its on-site generators. That connection decides where the site can go and when it can open.
• Every step is visible. Cable routes, substations, generator yards and building footprint all go through planning, and each can be contested.

Where CROSSOVER fits

• Power in 16 MW blocks. Each CROSSOVER unit is designed to deliver 16 MW at 800 V DC directly from the generator, on four isolated buses, so capacity can be added unit by unit as racks arrive.
• Behind the meter. CROSSOVER runs on natural gas from the pipeline, so a site does not have to wait for a large transmission connection.
• Fewer pieces of equipment. No medium- and low-voltage transformers, switchgear or separate rectifiers between the gas turbine and the racks; fewer components, no gearbox, a smaller footprint.
• Factory-built. CROSSOVER is built on skids from existing aero engines and set up from three 40 ft modules, with a 72-hour install as the engineering target.
• On the 800 V DC timetable. CROSSOVER targets its first unit and pilot in Q2 2028 and volume production in 2029.

On-site generation does not remove planning: fuel supply, emissions and noise are assessed like any other plant. What changes is the size of each step and the time to the first megawatt.

Read with care: Hyper Tech is not affiliated with Gwelyfenai Ltd, Canolfan Ddata Menai, Vantage or Nebius, and takes no position on the planning application, which is for the council and the Welsh Government. Details of the proposal are as reported by the sources below; the 450 MW figure is TechRadar’s. CROSSOVER is a development program; ratings, install times and dates are design targets.

Sources

1. Nation.Cymru: report on the planned protest and the application, October 8, 2026.
2. TechRadar: “Controversial North Wales data center the size of ‘57 football pitches’ sees opposition from tens of thousands”, October 14, 2026.
3. Place North West: report on the call-in request, October 15, 2026.
4. Vantage Data Centers: “Vantage Data Centers and Nebius Expand UK AI Infrastructure with First Deployment in South Wales AI Growth Zone”, August 13, 2026.
5. Hyper Tech: CROSSOVER, power for AI data centers and CROSSOVER: 72 hours to power.

Earlier posts: Vantage reserves 1 GW of 800 V DC converters · NVIDIA’s DSX POD and 800 V DC power on site · Google’s Detroit-area data center and Midwest power · 16 MW blocks at 800 V DC: what NVIDIA showed at OCP