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By NiLu Updated

Data centers — energy and environmental impacts

How power, energy, water, emissions, and local impacts relate — and which limits prevent universal conclusions.

In brief

  • Power, energy, connected capacity, and actual consumption are not equivalent.
  • Global pressures can look limited while certain territories face strong concentration.
  • Water and emissions depend on the boundary, architecture, and location considered.
  • Data gaps by site and region must accompany any public conclusion.

Energy is not a single metric

MW describe power at a given moment. MWh and TWh describe energy over time. Requested, reserved, installed, energized, usable, and consumed capacity are not equivalent. [1] [2]

A project can have land and a building before it has a sufficient electrical connection. Grid, substation, transformers, switchgear, UPS, generators, and cooling each have their own schedules. [1] [2]

Territorial concentration

The sector’s global share can look limited while certain markets face much greater pressure. In Ireland, data centers accounted for 23% of measured electricity consumption in 2025. The case demonstrates concentration, not a worldwide rule. [3]

Projections also need to remain attributed. Scenarios for 2030 depend on equipment, utilisation, efficiency, deployment, and energy availability. They are not a guarantee that the grid will meet all projected demand. [1] [2]

Water and cooling

Water consumption and withdrawal are different metrics. It is also necessary to separate potable, non-potable, and reused water; direct on-site use and indirect use in electricity generation.

An LBNL study found variation greater than four orders of magnitude in water consumption per workload across the evaluated combinations of equipment, utilisation, cooling, climate, power grid, and hardware refresh. That does not represent the observed distribution of all sites and does not authorize a universal “per query” number. [4]

Liquid cooling can reduce certain loads or enable higher densities, but its environmental effect depends on the complete architecture and the final form of heat rejection. [5]

Emissions

Operational emissions depend on the electricity consumed, timing, and location. Location-based and market-based Scope 2 answer different accounting questions. [6]

A PPA or certificate can support a market-based claim without proving that consumption was met by carbon-free generation in every hour. Proposals for hourly matching and physical availability should not be confused with every rule currently in force. [6]

There are also embodied emissions in construction, servers, electrical equipment, and cooling. Today, methods and inventories do not offer an independent baseline that is sufficiently comparable for the whole sector.

Local impacts

Beyond energy and water, projects can alter land use, noise, heat, infrastructure, and territorial planning. Local case studies demonstrate mechanisms and conflicts in specific jurisdictions; they do not measure global prevalence. [7]

Uncertainties that remain

  • public and comparable water by site;
  • generator operating time and real emissions;
  • comparable embodied carbon;
  • cumulative regional impacts;
  • energized versus actually usable capacity.

These uncertainties must accompany any public synthesis.

References

  1. IEA — Energy and AI (2025). IEA. Accessed July 22, 2026.
  2. IEA — Key Questions on Energy and AI (2026). IEA. Accessed July 24, 2026.
  3. CSO Ireland — Data Centres Metered Electricity Consumption 2025. Central Statistics Office Ireland. Accessed July 24, 2026.
  4. LBNL — The water use of data center workloads (2025). Lawrence Berkeley National Laboratory. Accessed July 24, 2026.
  5. U.S. DOE FEMP — Cooling Water Efficiency Opportunities for Federal Data Centers. U.S. Department of Energy. Accessed July 24, 2026.
  6. GHG Protocol — Scope 2 Guidance. GHG Protocol / WRI. Accessed July 24, 2026.
  7. JLARC — Data Centers in Virginia (2024). Virginia JLARC. Accessed July 24, 2026.