The proposed hyperscale AI data centre at Auchtertool could emit as much NOx air pollution as the nearby Shell liquified gas plant under normal operations according to calculations.
This was covered in the Sunday Mail
John Swinney told to halt ‘hyperscale’ AI data centre plans amid fears of mass pollution 21/06/2026
Data centres require diesel generators for emergency back up generation as they need to be online 24/7. These generators need to be tested throughout the year to ensure they are in working order and the calculations have been done from the routine testing, rather than the emergency operation.
The developers of the 600MW hyperscale AI data centre have not been required to do an environmental impact assessment and have very vague statements about the back-up generators, not disclosing the number or size. However it is clear that all hyperscale data centres need backup generation for the full capacity of the data centre to prevent outages and ensure the standard 99.999% uptime required. They mention that they would be non fossil fuel. This means biodiesel which is the same chemical as diesel, but which comes plant or animal fats instead of mineral oil.
Researcher and journalist Petra Matijevic, who did a study of the air pollution impacts of the Larbert hyperscale data centre which was published in the National, did a follow up on what we know about the Auchtertool application. [1]
Figures from the detailed air pollution report, which was part of the EIA for the 300MW data centre at Larbert, were used to estimate the pollution that would be created by the Fife data centre if they used the same generators specified in the EIA. [3]
Since the Auchtertool developers will not need to do an EIA we will not get a similarly detailed analysis as the one done so this needs to be an estimate. We have no idea what generators they would use but this gives a ball-park figure for air pollution.
The Larbert data centre is 300MW but has 640MW of backup generation, just a bit more than that required as a minimum at Auchtertool.
Using the energy demand for generators Petra found that three generators would need to be operating eight hours a day on every working day of the year which would create a large amount of air pollution roughly equivalent to that produced by Shell’s Fife natural gas liquids plant a mile away at Mossmorran [2]. This plant will stay open when the Fife ethylene plant closes and so will be the only emissions coming from the site at Mossmorran by the time this data centre would open.
With a 600 MW data centre, it would have at least 188 generators of Larbert size, not including any redundancy (they would add extra in case some of them fail during emergency).
Based on 188 generators of the same type as specified for Larbert, we calculated that the generators would release at least 271 tonnes of NOx (nitrogen oxide) gases a year just from routine testing operations, which would make the development a large-scale industrial polluter and place it firmly above SEPA’s reporting threshold of 100 tonnes for yearly exhaust gas releases. The latest reporting figures for Shell’s Fife NGL Plant at Mossmorran showed it emitted 280 tonnes of Nox gases in 2024. [2]
In order to fulfil the testing schedule, due to the large number of generators rewired, any three of the generators would be operational for their 1- and 4-hour staggered scheduled testing for an 8 hours every working day, releasing more than a tonne of NOx a day.
Despite this, the data centre has not been required to do an EIA. And so will not be required to do an Air Quality Assessment of the type done for the Larbert site.
Dr Kat Jones, Director of APRS said:
“The hyperscale data centre at Auchtertool has not been required to do an Environmental Impact Assessment and so we have had to estimate these figures from what we know from the Larbert site.
“To find out that this level of air pollution could be produced by this development, which the developers are trying to tell us is a ‘green data centre’; and which did not require an Environmental Impact Assessment is shocking.
“When you have a development that uses the energy of 600,000 homes and needs diesel back-up for to keep on 24/7, then even with routine testing they are going to breach safe air pollution limits. And when there is a power interruption and the generators are on emergency power it will be completely off the charts.
“The Scottish Government cannot allow these hyperscale AI data centres to be permitted for so many reasons, but surely the most important and critical is people’s health. We are calling on them to put in place an immediate moratorium which they investigate the impacts of hyperscale AI data centres on Scotland’s communities, electricity grid and environment.”
“This analysis is surely the most compelling reason why the Scottish Government needs to put a moratorium on all applications for hyperscale data centres to allow time for them to go on schedule 1 of the EIA regulations so all will be required to conduct proper and detailed environmental checks.”
Notes
[1] The Fife calculation was done as a follow up to the work Petra Matijevic did looking at the Larbert data centre air pollution figures. These calculations are laid out on the APRS website https://aprs.scot/news/larbert-data-centre-will-be-top-10-polluter/ – and the story was published in the National 18 June 2026
[2] SEPA polluter register is here: https://informatics.sepa.org.uk/SPRI/
We have downloaded all the NOx polluters that need to report and highlight Mossmorran which reported 0.28 Nitrogen oxides, NO and NO2 as NO2 (kt) in 2024, the last reporting period published.
Once the Fife ethylene plant at Mossmorran closes the remaining plant at Mossmorran will be the Fife Liquified Natural Gas (LNG) Plant. This is is the 14th most polluting site in Scotland for NOx air pollution emissions. It is highlighted bold in the table below.
| Facility | Description | Nox emissions (kilotonne) 2024 |
| Lerwick Power Station, Shetland | Energy sector | 1.5 |
| Fife Ethylene Plant, Mossmorran | Chemical industry | 0.99 (closing in 2026) |
| Tarmac Ltd, Dunbar Plant, E.Lothian | Mineral industry | 0.72 |
| O-I Manufacturing UK Ltd Glasshouse Loan Allo | Mineral industry | 0.66 |
| Shell UK Ltd, St Fergus Gas Plant | Energy sector | 0.66 |
| INEOS Chemicals Grangemouth Ltd, Grangemouth | Chemical industry | 0.46 |
| Grangemouth Refinery | Energy sector | 0.4 |
| Sullom Voe Terminal, Shetland | Energy sector | 0.35 |
| Dunbar ERF , Dunbar | Waste and waste-water management | 0.34 |
| Girvan Distillery | Animal and vegetable products from the food and beverage sector | 0.29 |
| INEOS Infrastructure (Grangemouth) Ltd | Energy sector | 0.29 |
| Stevens Croft Power Station, Lockerbie | Waste and waste-water management | 0.29 |
| Caledonian Paper Mill, Shewalton, Irvine | Paper and wood production and processing | 0.28 |
| ***Fife Natural Gas Liquidation Plant*** | ***Energy sector*** | ***0.28*** |
| Peterhead Power Station | Energy sector | 0.28 |
| Earls Gate Energy Centre, Grangemouth | Waste and waste-water management | 0.27 |
| Grangemouth CHP, Boness Road, Grangemouth | Energy sector | 0.26 |
| MVV Baldovie Incinerator, Dundee | Waste and waste-water management | 0.25 |
| Ardagh Glass, Portland Place, Irvine | Mineral industry | 0.21 |
| Egger, Barony Rd, Ayr | Paper and wood production and processing | 0.21 |
| Millerhill Recycling & Energy Recovery Centre | Waste and waste-water management | 0.2 |
| INEOS FPS Ltd, Kinneil Terminal, Grangemouth | Energy sector | 0.19 |
| Station Rd, Cowie | Paper and wood production and processing | 0.16 |
| Flotta Terminal, Orkney | Energy sector | 0.15 |
| RWE Markinch Limited, Glenrothes | Waste and waste-water management | 0.15 |
| Norbord Ltd, Morayhill, Inverness | Paper and wood production and processing | 0.13 |
| STS Precision Cleaning Services | Chemical industry | 0.1 |
[3] On the methodology:
The exact generators that will be used are unknown as there is scant detail in the application for the Auchtertool AI data centre final data centre operator is not yet known. However we have used the calculation from the Air Quality assessment from the EIA for Larbert data centre for the calculations. This environmental impact assessment report used model KD-3750-E generators produced by a US-based company Rehlko as a likely product. These 3.2 MW generators each emit 7.9 grams of nitrous oxide gases every second of operating at half of their full capacity and 15.3 grams per second at full power, according to the filed documents.
The routine testing schedule described is:
“Monthly Testing: A basic operational test at 50% load for one hour, carried out once per month, with three generators (one generator per data hall) operated at a time;
Quarterly Testing: A load bank test at 100% load for four hours, carried out once per quarter, with three generators (one generator per data hall) operated at a time; and
Annual Testing: A full diagnostic test at 100% load for four hours, carried out once per year, with three generators (one generator per data hall) operated at a time.”
Based on this, each of the 200 generators would be operating 12 hours a year at 50% and 20 hours a year at 100% power, making the up the total emission numbers above.
The generator flue parameters – annex from the Air Quality Assessment report
EIA_Report_Appendix_6.3-_Generator_Flue_Parameters-1644563Download