Yet another proposed data centre is considering building an energy centre powered by gas, as Curtis Hall looks for a solution to grid delays for its Cardiff project. 

Curtis Hall has proposed building a data centre on the site of the Cardiff East Park and Ride, but it has reportedly been told that the 150MW of grid capacity it would need at full completion may not be available until sometime between 2030 and 2034. 

That’s a long time to wait for a grid connection, but is hardly unheard of in the UK’s data centre sector. In fact, earlier this week it was revealed the Nscale’s flagship project in Loughton, Essex, was suffering from similar grid delays, with UK Power Networks telling the firm that it wouldn’t have the power the site needs until the early-to-mid 2030s. 

While the delay at Nscale has ultimately led Microsoft to withdraw its backing for that particular data centre, Curtis Hall is eager to get its Cardiff data centre up and running even without a full grid connection. That’s why it’s proposing a temporary energy centre, with environmental assessments modelling up to 49.9MW of gas-fired generation.

That’s obviously lower than the grid connection it ultimately wants, but it could still mean the site can begin some operations much sooner. In fact, the temporary energy centre could begin operating in July 2028 and remain in use until approximately July 2033.

The assessments model gas turbines operating continuously during this period, rather than conventional backup generators used only during power outages.

While it is a potential solution to its power issues, Curtis Hall has stressed that the technology is just one solution to its problem and not necessarily the final one. The developer told the BBC that gas turbines were included because they represent a worst-case scenario for emissions and noise, with alternatives such as gas- or hydrogen-powered fuel cells still under consideration.

The company also said the temporary plant might not be required if the grid connection becomes available sufficiently early.

Why the 49.9MW figure matters

Given Curtis Hall eventually wants the site to have a 150MW grid connection, it looks set to settle on 49.9MW – so why is that? Well, it’s because it sits just below the 50MW threshold at which non-wind electricity-generating stations fall within Wales’ Significant Infrastructure Projects consenting regime.

Under the Infrastructure (Wales) Act 2024, generating stations with an installed capacity of between 50MW and 350MW require Welsh ministerial infrastructure consent. While Curtis Hall has denied deliberately limiting the proposed capacity to avoid that requirement – it is rather convenient. 

There are also inconsistencies in the submitted environmental documentation. The project’s main development description specifies a maximum capacity of 47MW for the temporary energy centre, while the air-quality assessment uses 49.9MW. The legislation also defines installed generating capacity by reference to the maximum sustained output of the equipment, making the final configuration relevant to how the threshold applies.

The plans separately provide for 40 diesel standby generators, intended to maintain electricity supplies during outages once the permanent grid connection becomes available. Unlike the temporary energy centre, these would serve as emergency backup rather than the data centre’s primary electricity supply.

The proposed development has attracted substantial local opposition, including concerns over emissions, noise and the loss of the existing park and ride facility.

Environmental campaigners have criticised the prospect of running fossil-fuel generation for several years, although Curtis Hall maintains that the development would not have a significant impact on local air quality.

In September, the Welsh Government issued a holding direction preventing Cardiff Council from granting planning permission while ministers consider whether to take over the application. No final decision has been made.

Grid delays are changing data centre power strategies

Cardiff is just another example of UK data centre developers exploring alternative electricity supplies, however. In addition to the aforementioned issues with Nscale, a proposed 72MW data centre near Reading also has plans for 49.9MW of natural gas fuel cells to power its initial development.

That project currently has just 1.8MW of grid capacity available, with reinforcement for a secured 60MVA connection not expected until 2037. Even then, the developer may need to retain on-site generation unless additional grid capacity can be secured.

It’s unlikely that these will be the only projects looking to generate more of their own power as a stop gap to a larger grid connection, however. In fact, microgrids may be essential in unlocking the next wave of growth in the data centre sector. That is at least until there is enough grid reinforcement work completed to actually handle the volume of data centres needed in the UK.