UK Developer Curtis Hall Proposes Temporary 49.9MW Gas Plant to Power Cardiff Data Center Campus

Plans for a major data center campus in Cardiff could hinge on a temporary natural gas power plant, as UK property developer Curtis Hall seeks permission to build on-site generation capacity just below the threshold that would trigger Welsh government oversight, according to reports from the BBC.

The proposed "temporary ancillary energy center" would consist of gas turbines with a combined capacity of up to 49.9MW, according to planning documents. The facility could begin operating in July 2028 and would remain in service until the site secures a full electricity grid connection, which is currently expected in July 2033. If built, the center would include five gas turbines, a steam generator, and two backup gas turbines, while the data center itself is ultimately expected to require 150MW of power from the grid.

The project highlights the mounting power constraints facing data center developers in the UK, where lengthy grid connection lead times have already prompted Microsoft and OpenAI to withdraw from proposed projects. Curtis Hall said the gas generation plan represented a "worst-case scenario" and that the facility would not serve as the data center's permanent power supply. "If the connection arrives in time, the energy center will not be needed at all," the company said, adding that gas turbines appear in planning documents because "they represent the worst case for emissions and noise, so assessing them tests the upper limit of any impact." The company also said it had not confirmed the nature of the generation technology and was open to alternatives such as fuel cells.

The proposal has drawn criticism, with opponents arguing that the 49.9MW capacity is an attempt to circumvent planning rules, as generation facilities of 50MW or more require approval from the Welsh government. The site is also expected to deploy 40 backup diesel generator sets. According to Cardiff Council, a range of council members have raised formal objections and are calling for the Welsh government to scrutinize the plans. The development, first reported in February, is slated for a park-and-ride facility in Llanrumney on an approximately 40-acre land parcel, with layouts setting out three data centers, an on-site substation, ancillary energy facilities, and an administration and storage building. Concerns have also been raised about the impact on local hospital services, as the park-and-ride serves as a key parking area for the University Hospital of Wales, the country's largest hospital.

The Cardiff proposal underscores a broader trend of data center operators turning to behind-the-meter generation to bridge the gap between soaring compute demand and constrained grid infrastructure, a stopgap that raises questions about emissions, local opposition, and the long-term role of fossil fuels in powering digital infrastructure.