Sustainability — Power, Water, Carbon

1 · The three numbers — PUE, WUE, CUE

All three are metrics defined by The Green Grid consortium. They're imperfect (operators choose boundaries cleverly) but they're the universal language for comparing facilities.

2 · Where the watts come from

A data center's CUE is dominated by the local grid mix. The same 100 MW facility produces:

3 · The hyperscaler pledges

• Microsoft — carbon negative, water positive, zero waste by 2030. Acknowledged in 2024 sustainability report that emissions actually rose ~30% since 2020 due to AI buildout.
• Google — 24/7 carbon-free energy by 2030 (every hour, every grid). Currently ~64% averaged.
• Meta — 100% renewable since 2020 (annual matched). Investing in long-duration storage (Form Energy) and geothermal.
• Amazon — 100% renewable globally, claimed 2023 (matched annually). The world's largest corporate buyer of renewables.
• Apple — already at net-zero on operations; targeting full supply chain by 2030.

The honest read: annual matching is much weaker than 24/7 matching. When solar dies at sunset and gas peakers ramp up, "100% renewable annually" companies are still emitting.

4 · Firm clean power — the new race

AI's 24/7 demand needs firm (always-on) clean power. The deals announced in 2024–2025 mark a new chapter:

• Microsoft + Three Mile Island — 20-year PPA to restart Unit 1 reactor (~835 MW). Targeted online 2028.
• AWS + Talen Energy — $650M acquisition of Cumulus Data adjacent to Susquehanna nuclear plant (~960 MW).
• Google + Kairos Power — small modular reactor (SMR) deal for ~500 MW by 2030.
• Google + Fervo Energy — 115 MW enhanced geothermal in Nevada (operational 2024).
• Meta + Sage Geosystems — 150 MW geothermal pilot in Texas.
• Oracle — announced gigawatt-scale SMR deployment (timeline unclear).

Source: Microsoft, AWS, Google, Meta press releases (2024-2025); IEA Electricity 2025 report; Lazard LCOE 2024.

5 · Water — the second front

Evaporative cooling consumes water — about 1.8 L per kWh of IT energy at typical sites. A 100 MW campus with PUE 1.20 and WUE 1.5 consumes ~1.5 million liters per day, comparable to a small town.

In water-stressed regions (Phoenix, Madrid, parts of Texas) operators are switching to closed-loop dry cooling — trading higher PUE for near-zero WUE. Microsoft committed in 2020 to a "water positive by 2030" pledge requiring replenishment of more water than they consume.

6 · Heat reuse

Heat doesn't have to go to a cooling tower. In cold climates with district heating networks, it's an asset:

• Stockholm — Stockholm Exergi sells heat from multiple DCs to ~10,000 apartments.
• Helsinki — Microsoft 2022 deal to provide up to 40% of city's district heat from a new DC.
• Frankfurt — Mainova's network ingests waste heat from ~10 DCs.
• Paris — Equinix PA10 supplies heat to the 2024 Olympic Village swimming pools.