When the press reports a "100MW data center," most readers have no mental model of what that means in terms of physical infrastructure. This explainer translates the headline number into the actual electrical equipment required — and why each component is currently difficult to procure.

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WHAT 100MW MEANS IN PRACTICE

100MW Data Center — Power Consumption Context 100 MW = 100,000 kW = power for approximately 80,000 European households
Annual electricity consumption: ~876,000 MWh at full load
Annual electricity cost at €60/MWh: approximately €52 million
Equivalent GPU clusters: approximately 50,000 H100 GPUs at full utilisation
PUE assumed: 1.3 (typical for modern AI data center)

THE TRANSFORMER REQUIREMENT

A 100MW data center needs to step down electricity from the grid voltage (typically 63kV, 90kV or 225kV in France) to the facility's internal distribution voltage (typically 11kV or 33kV). This requires one or more large power transformers.

Transformer Specification — 100MW Facility Required capacity: 120–130 MVA (including N+1 redundancy)
Typical configuration: 2 x 65 MVA transformers (100% redundancy)
Or: 1 x 130 MVA main + 1 x 130 MVA standby (full redundancy)
Current lead time at major OEM: 48–60 months
Current lead time at second-tier European manufacturer: 20–32 months

THE MEDIUM VOLTAGE DISTRIBUTION

From the main transformers, power is distributed through medium voltage switchgear to multiple transformer substations within the facility. A 100MW campus will typically have:

BACKUP POWER

AI workloads require extremely high availability — typically 99.999% uptime (5.26 minutes downtime per year). This requires multiple layers of backup power:

Backup Power Infrastructure — 100MW Facility UPS systems: 100–130 MVA of UPS capacity (typically battery-based)
Standby generators: 100–130 MW of diesel or gas generator capacity
Generator count: typically 20–40 units of 3–6 MW each
Generator lead time: 12–18 months (less constrained than transformers)

COOLING POWER

Cooling consumes a significant fraction of a data center's total power. For a 100MW IT load with a PUE of 1.3, approximately 30MW is consumed by cooling systems. AI-optimised facilities with liquid cooling may achieve PUE of 1.15–1.20, reducing cooling power to 15–20MW.

TOTAL ELECTRICAL EQUIPMENT BILL

Electrical Equipment Cost — 100MW AI Data Center Main power transformers: €3–8 million
MV switchgear and distribution: €2–5 million
UPS systems: €15–25 million
Standby generators: €20–40 million
Cabling and busbars: €5–10 million
Total electrical infrastructure: €45–88 million
As % of total data center build cost (€200–400M): 15–25%

THE PROCUREMENT TIMELINE REALITY

For a 100MW AI data center targeting energisation in Q1 2027, the main power transformer order needed to be placed by approximately Q1 2025 with a second-tier European manufacturer, or Q4 2022 with a major OEM. Projects that have not yet placed transformer orders should revise their commissioning targets accordingly.

The electrical equipment, which represents 15–25% of total build cost, is determining 100% of the schedule. This is the operational definition of a bottleneck.