Environmental permitting for data centres: what you need and when to apply

Jennifer Stringer, Technical Director, explains the environmental permits required for a data centre development - and when to apply.

Jennifer Stringer, Technical Director


You’re developing a data centre. To ensure security of power to the facility, a relatively small area of your site will be allocated to onsite emergency back-up generation. Typically, these generators will be fuelled by diesel and the installation of these units will usually trigger the need to obtain an environmental permit.

The permit will only cover the emergency back-up generators and any associated plant and equipment such as diesel storage tanks - not the wider data centre operations. And so, as a comparatively small part of the overall scheme, permitting may be considered as something that can be left until later (or even overlooked completely). But failing to properly manage permits early on can lead to unwanted (and avoidable) project delay.


What permit do I need?

There are various types of permits that could be triggered for emergency back-up generators, so understanding which permit you need is the first step. This will depend largely on the installed capacity (based on thermal input not electrical output of the generators) and the location of the site relative to sensitive receptors (third bullet point below) Applying for the wrong permit could end up costing you a considerable amount of time and money. So, it’s really worth seeking advice at an early stage to ensure you are applying for the right one.

The flow chart below provides a simplified visual to assist with this process.

Exemption back-up generators

Only very small back-up generators are exempt. They are units with an installed capacity of <1MW thermal input. Most data centres will have an electrical demand too high to be exempt from a permit.

Standard rules permit

A standard rules permit has advantages in terms of simplicity of the application, as well as the cost and timescale for securing a permit. However, in order to qualify for a standard rules permit, you need to check that your development proposal and site location meet all permit conditions, as there is no flexibility to change these. There’s currently only one standard rules permit option available to back-up generators and this is SR2018 No. 7.

Key qualifying requirements of this permit are:

  • Engines would have a thermal input ≥1MW but <20MW and <50MW in aggregate; and
  • Burn a qualifying fuel, this includes gas oil; and
  • Be located >5km from a SAC, SPA, Ramsar site, SSSI[1] or where the stack is a minimum of 3m above ground be >500m from any of these designated sites; and
  • Operate for no more than 50 hours per annum and <500 hours per annum for emergency duty.

If your back-up generators don’t meet the above criteria and aren’t exempt, then a bespoke permit is required.

Bespoke Medium Combustion Plant (MCP) permit

A bespoke MCP permit can be applied for where the installed emergency back-up generators have a thermal input, ≥1MW but <50MW in aggregate. MCP permits are focussed on air quality impacts and therefore have the advantage of a narrower scope of information to support the application, with lower regulatory costs and a quicker overall permitting timeline.

Bespoke Installation Permit

Where the installed capacity of the emergency back-up generation is thermal input ≥ 50MW in aggregate, a bespoke installations permit is required. These permits cover the potential impact from the back-up generators and associated fuel storage to all environmental media; meaning they require consideration of emissions to air, water, land, noise, dust, odour etc, as well as raw material consumptions, waste generation and energy efficiency. 

The potential impact on the land occupied by the facility and to the groundwater below it will also need to be considered over the course of its operational life. And so, during the application stage a baseline ground and groundwater condition will usually be defined; used to measure against the condition at the end of the facility’s permitted life.

If at that point the data centre is found to have caused contamination, then a permit surrender remediation would be required to return ground and ground water conditions to their baseline state.

[1] Special Areas of Conservation (SAC), Special Protection Areas (SPA), Sites of Special Scientific Interest (SSSI)

When to apply

In the development of data centres, programme is everything. And while you can construct a facility without a permit, a permit is essential to commission on fuel or bring the data centre into operation. Knowing when to apply - and how long to allow for regulatory determination and issuing - is therefore key to achieving a smooth project programme and speed to market.

In the UK, regulatory guidance sets out timelines for obtaining permits. These are however now overly optimistic. Duly making timelines were originally much shorter and an application could expect to be picked up for duly making within a month; but for many permits this is now four months or even longer. 

Determination timelines have also increased; particularly where assessments require audits of detailed air quality modelling which can commonly add six months.

To help you prepare the chart below illustrates current and typical timelines for the various permit types.

It’s also important to know that some permit types come with pre-operational conditions that need to be discharged before the facility can be brought into operation. In these instances, additional time needs to be built into your programme to allow for this – we would recommend at least three months.

All permit types require operators to have a written environmental management system (EMS) covering the operation of the permitted activity. This EMS will also need to be established before the facility is commissioned on fuel and subsequently brought into operation.

What if there isn't sufficient time?

In certain circumstances there are options that can be explored if the permit isn’t issued in time to commission your data centre. For most permits, a duly made application is the minimum requirement for the regulators to consider alternative options.

This option comes with some risk and should really only be used as a last resort, especially because there’s no guarantee an alternative will be agreed. 

As trusted data centre advisors, and with decades of experience helping clients to comply with UK environmental permitting regulations, we can advise on the most cost and time effective route for your development.

To discuss the permitting requirements for your data centre, get in touch using the form below.

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