24/7 Carbon-Free Energy: the new gold standard for hyperscalers
Beyond annualised 100% renewable, 24/7 CFE demands strict hourly coverage. Mechanics, cost and feasibility explained.
The end of annualised greenwashing
Buying 1 TWh of solar RECs in July to cover 1 TWh of December consumption is carbon time-shifting: the grid mix actually consumed remains fossil. Google and Microsoft buried that practice in 2020 by publishing the 24/7 CFE standard.
The exact metric
CFE Score = Σ (carbon-free energy consumed at hour h) / Σ (total energy consumed at hour h), across 8,760 hours.
A data center can be 100% renewable annualised while sitting at 62% hourly CFE. Targeting 95% hourly CFE radically changes PPA strategy.
The winning mix
- 40% solar (day cover)
- 30% wind (night + winter cover)
- 20% nuclear or hydro baseload
- 10% battery storage (smoothing)
Without nuclear or hydro, hitting 95% CFE costs 2.3× more (PPA multiplication + producer curtailment).
The real cost
| CFE level | Cost vs spot | Feasibility | |---|---|---| | 100% annualised | +0–5% | easy | | 80% hourly | +8–15% | reachable | | 95% hourly | +25–40% | demanding | | 100% hourly | +60–110% | hyperscalers only |
The Voltarione engine
Our matching engine computes in real time the achievable CFE score given listed producers + optional EDF/Vattenfall nuclear mix. Output: recommended PPA portfolio optimised for a target CFE threshold (e.g. 92%).
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