Evidence Series — Scottish Energy Compact — June 2026
Hyperscale data centres are among the most water-intensive industrial facilities ever built. Scotland’s planning system has no standardised requirement to assess abstraction volumes, cooling methodology, or catchment impact. Not one application in the current pipeline has been subject to a published cumulative water impact assessment.
Section 1 — How Much Water Do These Facilities Use?
Data centres generate enormous quantities of heat. Every server, every switch, every power unit converts electricity into computation — and waste heat. At hyperscale, that heat must be removed continuously, around the clock, every day of the year. The choice of cooling method determines whether a facility draws millions of litres of water per day from the local supply system, or near-zero. That choice is currently made by the developer, disclosed inconsistently, and never independently verified before planning consent is granted.
The three principal cooling methods have radically different water demands. The Compact prohibits the first:
Water is circulated through cooling towers where it absorbs heat and evaporates. Approximately 80–85% of water withdrawn is lost permanently to the atmosphere and does not return to the water supply. At the Green Grid industry benchmark of 1.8 litres per kWh of IT load, a 500MW facility at 80% utilisation draws 17–19 million litres per day — around 6.9 billion litres per year. This requires a dedicated 450–600mm mains feed at sustained industrial pressure. In Fife, where Lomond Hills reservoirs stand at 21% of capacity (30-year low) and the River Eden catchment has had abstraction licences suspended under SEPA’s Significant Scarcity designation, this volume cannot be accommodated without material harm to existing users and environmental flows. The Compact prohibits evaporative cooling for all facilities above 200MW.
Modern hyperscale facilities use outside air directly for cooling, drawing on ambient temperature rather than water evaporation. Scotland’s cool climate is a genuine engineering advantage: air-side economisation is effective for more days per year in Scotland than in most of Europe. Annual water consumption falls to approximately 1–2 million litres per day for backup only — a reduction of 90% or more compared to evaporative cooling. Google’s Waltham Cross facility uses advanced air-cooling systems limiting water consumption to what Google describes as “domestic levels.” This is the standard the Compact requires.
Adiabatic systems use water misting to pre-cool incoming air without direct contact cooling towers. Water consumption is significantly lower than wet tower evaporative cooling but still material at hyperscale — a 100MW facility may draw 3–5 million litres per day in peak summer conditions. Permitted under Condition 3 only where the applicant submits an independently verified WUE declaration demonstrating compatibility with SEPA Environmental Authorisation requirements for the relevant catchment, and where SEPA confirms the authorisation in principle before consent is granted.
| Facility Size | Cooling Method | Peak Daily Use | Annual Use |
|---|---|---|---|
| 100MW | Evaporative | ~5.2M litres | ~1.9bn litres |
| 100MW | Air-side hybrid | ~0.8M litres | ~280M litres |
| 500MW | Evaporative | ~19M litres | ~6.9bn litres |
| 500MW | Air-side hybrid | ~3.5M litres | ~1.2bn litres |
| Full pipeline (8,700MW) | Mixed | Up to 330M litres | Up to 120bn litres |
Estimates based on US DoE and Lawrence Berkeley National Laboratory benchmarks applied to Scottish pipeline. Peak daily figures assume summer conditions at maximum evaporative load. Air-side hybrid assumes 85% air-side, 15% evaporative at peak. Full pipeline estimate is indicative upper bound.
The industry metric for water consumption is Water Use Effectiveness — litres of water consumed per kilowatt-hour of IT load. The global average WUE for data centres is approximately 1.8 L/kWh. Best-in-class facilities achieve 0.2–0.5 L/kWh. No Scottish planning application has been required to declare a WUE target or commit to one as a condition of consent.
Source: Uptime Institute Global Data Centre Survey 2024; Green Grid WUE whitepaper
Section 2 — Scottish Catchments at Risk
Scotland’s water resources are generally abundant but unevenly distributed and seasonally variable. Summer low-flow periods in Scottish rivers can be severe — particularly in the east, where several of the largest proposed sites are located. The cumulative abstraction of multiple large facilities drawing from the same or connected catchments in a hot, dry summer has never been modelled.
The ILI Group planning submission for Auchtertool declared a water demand of 93,000 litres per day — presented as equivalent to 239 homes. At the Green Grid industry benchmark of 1.8 litres per kWh of IT load, a 500MW facility at 80% utilisation requires 17–19 million litres per day under evaporative cooling: up to 200 times the declared figure. Scottish Water confirmed capacity for the declared figure but noted the existing mains pipe is already too small. Lomond Hills reservoirs — the primary drinking water source for Fife — stood at 21% of combined capacity in 2025, the lowest level in 30 years. The River Eden catchment feeding the same supply zone has had abstraction licences suspended under SEPA’s Significant Scarcity designation in both 2022 and 2025. In May 2025 SEPA confirmed all of Scotland was at some level of water scarcity. No planning authority has required the applicant to reconcile its declared demand with industry benchmarks.
Sources: The Courier, “Water chiefs speak out on Fife AI data centre supply claims”; Scottish Water Annual Report 2024/25; SEPA Water Scarcity Report 15 May 2025; Green Grid WUE White Paper #35
Ravenscraig (550MW, Apatura), Drumshangie (500MW, Apatura) and Newhouse (400MW, ILI Group) form a cluster of over 1,450MW in North Lanarkshire. All three draw on the same regional water infrastructure and potentially the same catchment systems. No cumulative water assessment has been published for this cluster. Each application has been treated in isolation by the planning authority.
The Killean site carries an option to expand to 2,000MW — the largest single facility in the pipeline. Argyll’s west coast location provides relatively high rainfall, but the site’s scale means water demand at peak could exceed local catchment capacity during drought conditions. No hydrological impact assessment has been published for the full 2,000MW scenario.
Hurlford (540MW) and Ochiltree (200MW) sit in East Ayrshire, both drawing on the River Irvine catchment system. Combined peak water demand from these two sites alone could reach 24 million litres per day under evaporative cooling. The River Irvine is already subject to abstraction pressures from agricultural and industrial users.
Duns (225MW) and Coldstream (300MW) sit in the Scottish Borders, close to the River Tweed system — one of Scotland’s most ecologically important rivers and a designated Special Area of Conservation. Any significant abstraction from connected catchments would require SEPA scrutiny. No such assessment has been published or required.
Hunterston (~450MW) and the proposed Irvine site (1,000MW pre-planning) represent over 1,450MW on the North Ayrshire coast. Both sites are coastal, which opens the possibility of seawater cooling — as used at Google’s Hamina facility in Finland. However, no cooling methodology has been specified for either site, and seawater cooling carries its own environmental impact requirements under the Marine (Scotland) Act 2010.
Scotland’s planning system currently assesses each data centre application in isolation. There is no requirement for a developer to consider the combined water abstraction impact of neighbouring facilities. There is no requirement for SEPA to publish a catchment-level assessment of cumulative demand before consent is granted. The Scottish Government has issued no guidance to planning authorities on how to assess water impact for facilities of this scale. This is a structural gap in the consent process — not a fringe concern.
Section 3 — The Regulatory Position
The Scottish Environment Protection Agency (SEPA) is the statutory body responsible for regulating water abstraction in Scotland. SEPA has the powers to require abstraction licences for significant water extraction. However, the current planning process for data centres does not systematically trigger SEPA involvement at the pre-application stage.
The result is that planning authorities grant consent without a binding SEPA abstraction assessment in place. By the time a facility is built and operational, the abstraction is a fait accompli — enforcement against an operational facility consuming millions of litres per day is politically and practically difficult.
The planning system currently asks communities to accept major new water-intensive infrastructure without a transparent evaluation of the impact on local rivers, lochs, and groundwater. That is a failure of due diligence, not a fringe concern.
Michael Knox — Scotland’s Data Centre Reckoning, June 2026From 1 November 2025, the EASR superseded the Controlled Activities Regulations 2011 as the primary licensing framework for water abstraction in Scotland. Any abstraction above 50 cubic metres per day requires formal Environmental Authorisation from SEPA. A 500MW data centre under evaporative cooling draws approximately 19,000 cubic metres per day — requiring a full Complex Licence. This authorisation is currently sought after planning consent is granted, not as a precondition of it. By that point, the infrastructure investment creates pressure to authorise regardless of catchment conditions. The Compact closes that sequence: SEPA authorisation must be confirmed in principle before consent is granted.
The ILI Group declared a water demand of 93,000 litres per day for the 600MW Auchtertool facility. Scottish Water confirmed capacity for that figure. At the Green Grid industry benchmark of 1.8 L/kWh, the same facility under evaporative cooling would draw 17–19 million litres per day — up to 200 times the declared figure. There is currently no requirement for a planning authority to verify a developer’s water demand declaration against industry benchmarks, or to require independent WUE assessment before accepting it. NPF4 contains no guidance on WUE targets, cooling methodology disclosure, or maximum abstraction declarations for data centre applications. The gap between the declared figure and the benchmark figure is not a rounding error. It is the difference between a standard connection and a municipal supply system.
Ireland’s experience is directly relevant. Ireland’s 2020 Data Centre Strategic Review found that data centres accounted for 14% of national electricity consumption and raised significant water concerns. By 2021, several Irish local authorities were refusing data centre applications citing water infrastructure constraints. The cumulative impact had not been assessed before the pipeline was approved — exactly the position Scotland is now in.
Section 4 — What Must Change
The Scottish Energy Compact’s Condition 3 covers water impact and cooling standards. It requires no new primary legislation — it requires a ministerial direction to SEPA and planning authorities, and an amendment to NPF4 guidance. Both are within the Scottish Government’s existing devolved powers.
Mandatory WUE declaration. Every application above 50MW must submit a Water Usage Effectiveness declaration using Green Grid standard methodology, independently verified, specifying cooling system, WUE target in litres per kWh of IT load, and the resulting maximum daily and annual abstraction volume. The water source, Scottish Water connection point, and required pipe diameter must be named in the application.
Evaporative cooling prohibited. Closed-loop or air-side economisation cooling is mandatory for all facilities above 200MW. Evaporative and open-loop cooling are not permitted. Scotland’s current catchment conditions — Lomond Hills at 21% capacity, River Eden at Significant Scarcity with suspended abstraction licences, all Scottish catchments at some level of water scarcity as of May 2025 — make the 17–19 million litre daily abstraction of evaporative cooling at this scale incompatible with the Water Framework Directive environmental flow requirements for any Fife catchment.
SEPA Environmental Authorisation before consent. A SEPA Environmental Authorisation (under the Environmental Authorisation (Scotland) Regulations 2018) confirming the abstraction is permissible must be obtained or confirmed in principle before planning consent is granted — not after. The authorisation must address individual and cumulative catchment impact. A planning consent granted before SEPA authorisation is confirmed treats water as someone else’s problem. It is not.
Cumulative catchment assessment. A cumulative water abstraction assessment covering all proposed and consented facilities drawing from the same catchment or Scottish Water supply zone must be submitted alongside each individual application. Each application is currently assessed in isolation. The combined pipeline has never been modelled against available catchment capacity.
Developer pays for infrastructure. The applicant bears the full cost of any required upgrade to Scottish Water’s distribution network as a condition of consent. Annual WUE performance must be reported to SEPA and the planning authority. All assessments, authorisations, and annual reports must be published in full on the relevant planning authority’s portal. Facilities failing their declared WUE target within three years face mandatory consent review.
Pending the full Compact, one action can be taken immediately within existing powers:
MINISTERIAL DIRECTION — NOW
The Cabinet Secretary for Net Zero and Energy should issue a ministerial direction to SEPA and all Scottish planning authorities requiring standardised water abstraction and cooling methodology assessments for any data centre application above 50MW, with all results published before consent is determined.
This requires no new legislation. It requires no amendment to primary statute. It requires a minister to sign a direction.
US Department of Energy — Data Centre Water Usage report
Lawrence Berkeley National Laboratory — Data Centre Water Benchmarking Study
Uptime Institute — Global Data Centre Survey 2024
Green Grid — Water Use Effectiveness (WUE) whitepaper
SEPA — Water Environment (CAR) Regulations guidance
NPF4 (2023) — Scottish Government
Ireland Data Centre Strategic Review 2020
ASHRAE TC 9.9 — Thermal guidelines for data processing environments
Schneider Electric WP-176 — Adiabatic cooling in data centres
Marine (Scotland) Act 2010 — seawater abstraction requirements
River Tweed SAC designation — NatureScot