Will more AI data centres mean higher electricity bills and water use? One figure cannot answer that. A report today raised the lack of consistent disclosure of actual electricity and water use at Korean facilities. Here is how to read a project plan or environmental report.
Sources checked at 13:03 KST on September 30, 2026. Today's Hankook Ilbo report prompted the question; figures and definitions were checked against the IEA's updated analysis, the US Department of Energy's design guide and cooling-water guidance. A global projection is not the measured result of a Korean facility.
Key points
- The IEA’s roughly 950 TWh for 2030 is a global projection, not a local measured figure.
- Distinguish MW from MWh and read PUE and WUE alongside total electricity and water use.
- Check cooling, water source, measurement period and off-site power-generation boundaries.
Three-point summary
- The IEA estimates 485 TWh of global data-centre electricity use in 2025 and projects about 950 TWh in 2030. The second number is a forecast, not an observation.
- PUE is total facility energy divided by IT energy; site WUE is annual on-site water use divided by annual IT energy. Neither ratio alone reveals the total or the local impact.
- Ask for annual total electricity, on-site water use, cooling method, measurement period and the boundary used for water associated with power generation.
Is 950 TWh the figure for a local data centre?
No. The IEA's 2026 global outlook sees total data-centre electricity use rising from 485 TWh in 2025 to about 950 TWh in 2030. Demand at AI-focused centres could grow faster, but chip, grid and investment bottlenecks affect the outcome. A global annual projection cannot be turned into a confirmed city demand or a household bill increase.
Locally, distinguish a facility's contracted capacity in MW from its actual annual consumption in MWh. MW is a rate of power; MWh is energy over time. Only in a hypothetical case where a 100 MW facility draws 100 MW every hour would one day equal 2,400 MWh. Actual utilisation and cooling loads change annual use. Grid effects also depend on the connection point and supply plan. US DOE on regional grids
Does a low PUE solve the water question?
PUE is total facility energy divided by IT equipment energy. In the US DOE guide, a value closer to one means a smaller share goes to cooling, lighting and other non-IT loads. But if server workloads differ, a lower PUE alone does not prove a lower total electricity bill. Metric definition
Water needs a separate measure. Site WUE uses L/kWh: annual water used at the site divided by annual IT electricity. Cooling towers evaporate water to reject heat, so cooling design and climate matter. A measure that also counts off-site water used in electricity production has a different boundary from site WUE. Cooling that saves water can also require more power; read the metrics together. DOE on WUE · design guide
From capacity to local impact
Check totals and boundaries, not one number.
- 01CapacityMW: power at a moment
- 02Actual useMWh: energy over time
- 03EfficiencyPUE, WUE and denominators
- 04Local settingWater source, grid, climate
This is an editorial concept diagram, not measurements or a ranking of a particular facility.
Five fields to check in a report
| Field | Figure or explanation to seek | Easy mistake |
|---|---|---|
| Scale | Contracted MW and measured annual MWh | Treating maximum capacity as consumption |
| Power efficiency | PUE plus total and IT energy for the same period | Treating low PUE as low total use |
| On-site water | Annual withdrawal and consumption, WUE and water source | Treating L/kWh as the whole local burden |
| Indirect effects | Power supply and boundary for off-site water and emissions | Assuming site figures include everything |
| Comparison | Year, utilisation, cooling design and location | Ranking unlike facilities on one ratio |
In a hypothetical comparison, site A reports a low PUE and site B reports low on-site water use. That does not settle which is better for a community. You need the same-period total electricity, cooling design, source of water and local grid conditions. Hankook Ilbo noted gaps in standardised Korean operating data; that is no licence to invent missing facility figures. September 30 report
What should residents and users ask?
For a proposed facility, ask whether projected and measured annual power and water use are shown separately, where water comes from, how cooling changes in heat or drought, and how often results will be disclosed. In a company report, check the denominators and boundaries of PUE and WUE, and distinguish renewable-power procurement from power actually used hour by hour. If those details are absent, first ask what an “efficient” claim is being compared with.