Summary
- The permit covers 129 standby generators serving four proposed data centre buildings and ancillary infrastructure.
- The emergency plant has approximately 925MW of installed thermal input and may use HVO or gas oil.
- Conditions govern emissions, testing, fuel storage, drainage, pollution controls, and operational management.
The Environment Agency has issued Amazon Data Services UK an environmental permit for the standby generation plant proposed at its Didcot North Data Centre Campus in Oxfordshire.
The permit covers 129 emergency generators with a combined installed thermal input of approximately 925MW. The units would support four data centre buildings and associated infrastructure if the campus lost its mains electricity supply.
Of the total, 122 would be main backup generators serving the four data centre buildings. Four house generators would support non-critical building loads, while three smaller units would serve the substation and the site’s central industrial water building.
The generators are expected to use hydrotreated vegetable oil as their primary fuel, although the permit also allows gas oil. Each unit would have an individual exhaust stack, with the largest group terminating 33 metres above ground level.
The permit authorises a combustion activity under the Environmental Permitting Regulations because the total thermal input exceeds the 50MW threshold. It does not replace planning permission, a grid connection, building-control approval, or the other consents required to construct and operate the wider campus.
The regulated pollutants include nitrogen dioxide, carbon monoxide, particulate matter, and sulphur dioxide. The generators would operate during mains failures and undergo routine maintenance testing, creating a different emissions profile from continuously operating power plant but still requiring controls because of the number and combined scale of the units.
The Environment Agency’s introductory note identifies approximately 2,428 cubic metres of fuel storage across bulk tanks, unloading areas, and generator belly tanks. Bunding must provide containment of at least 110% of capacity.
Backup power defines the permitted installation
The site occupies approximately 23 hectares of the former Didcot A coal-fired power station, including land previously used for coal storage and the cooling towers. Reusing a former generation site provides an established industrial setting, but the permit shows how the electrical resilience requirements of a large data centre create a substantial regulated installation in their own right.
The emergency plant’s 925MW thermal input should not be read as the campus’s IT load. Thermal input measures the fuel energy supplied to the engines, not the electrical output available to servers. Engine efficiency, auxiliary demand, redundancy design, and the number of units running during an incident all affect the usable electrical capacity.
The scale nevertheless indicates the resilience architecture being planned. Four buildings supported by 122 principal generators imply extensive distributed backup provision, with additional units protecting building services, the substation, and water infrastructure.
Environmental conditions extend beyond stack emissions. Surface water from generator compounds, hardstanding, roofs, and fuel-handling areas must pass through the site drainage system and oil separation before discharge towards Moor Ditch.
The permit also requires a written environmental management system, competent staffing, maintenance records, accident controls, and procedures for preventing and responding to pollution. Testing schedules form part of the operating techniques against which compliance can be assessed.
The Environment Agency identified 27 Sites of Special Scientific Interest and three Special Areas of Conservation within its wider 15-kilometre screening area. The closest residential properties are approximately 600 metres southeast of the permitted installation, while an industrial park lies close to the eastern and southern boundaries.
Didcot’s history as a power-generation location does not remove the need to demonstrate that a new form of energy-intensive infrastructure can operate within current air-quality and environmental standards. The permit converts the application’s proposed controls into enforceable conditions.
It also illustrates the regulatory exposure attached to standby systems as data centre campuses become larger. Emergency generators may run infrequently, but their aggregate fuel storage, testing regimes, emissions, drainage, and maintenance requirements can place them within the same permitting framework used for major industrial combustion activities.
The permit was determined on 27 July and published by the Environment Agency on 3 August. Amazon must now comply with its conditions if the standby installation is built and operated, while the broader campus remains dependent on the delivery of its remaining construction, power, and planning requirements.
