Le plafond de la colocation : la FERC met fin à la gratuité du réseau pour les grandes entreprises technologiques

Key Takeaways

• Loophole Closed: On December 18, 2025, the Federal Energy Regulatory Commission (FERC) unanimously ruled that PJM’s current rules for co-located loads are “unjust and unreasonable.”
• Fair Share Requirements: Data centers co-located with power plants (like Amazon’s deal at Susquehanna) can no longer avoid paying for transmission backup while remaining connected to the public grid.
• New Transmission Classes: FERC directed PJM to create three new categories of transmission service tailored for loads that can limit their grid usage during peak times.
• Deadlines loom: PJM has until January 17, 2026, to file its new tariff revisions, ending months of uncertainty for nuclear-powered AI factories.

The End of the “Behind-the-Meter” Free Ride

For the past year, a quiet war has been raging between the world’s wealthiest tech giants and the utilities that manage the American electrical grid. At the center of this conflict is “co-location”—the practice of building a massive AI data center directly next to a power plant, usually a nuclear one, to bypass the traditional queue for grid interconnection.

Big Tech argued that because they were “behind-the-meter,” they shouldn’t have to pay for the massive transmission lines that keep the rest of the grid stable. Utilities and consumer advocates disagreed, arguing that if the nuclear plant goes offline for maintenance, those data centers immediately “fall back” onto the public grid, consuming power that should be going to hospitals and homes.

On December 18, 2025, FERC finally chose a side. In a rare 5-0 unanimous decision, the commission ruled that the status quo is fundamentally broken. Data centers can no longer have it both ways: they cannot enjoy the reliability of the grid without paying for the infrastructure that provides it.

Technical Deep Dive: The ISA and the Fallback Paradox

To understand the ruling, one must understand the Interconnection Service Agreement (ISA). This is the legal “umbilical cord” between a power plant and the grid.

The Problem: Nameplate Capacity

Traditional ISAs were designed for a one-way flow: the plant makes power, and the grid takes it. When a data center co-locates, it essentially “siphons” power before it ever hits the high-voltage transmission lines. Tech firms like Amazon previously attempted to amend these ISAs to increase the co-located load from 300 Megawatts (MW) to 480 MW without paying for additional grid upgrades.

The “Fallback Paradox” occurs because physics doesn’t recognize legal contracts. If a 1,000 MW nuclear reactor trips and shuts down, the 480 MW data center doesn’t just turn off; it tries to pull that 480 MW from the surrounding grid. Without proper transmission backup, this surge can cause voltage drops or rolling blackouts for neighbors.

The Solution: Conditioned Services

FERC’s order directs PJM to create three new types of transmission service. These are not “all-or-nothing” connections. Instead, they allow data centers to:

1. Limit Withdrawals: Automatically throttle power usage during grid emergencies.
2. Request Partial Service: Pay for only the amount of backup they actually need, rather than the full nameplate capacity of the data center.
3. Surplus Interconnection: Use “surplus” capacity left over at existing power plant sites that haven’t been fully utilized.

This approach uses Levelized Cost of Transmission (LCOT) math to Ensure that the data center pays a pro-rated share of the grid’s upkeep. If a data center uses the grid for backup only 5% of the year, they shouldn’t pay 100% of the cost—but they can no longer pay 0%.

Background: The Susquehanna Catalyst

The path to this ruling began with the Susquehanna Nuclear Steam Electric Station in Pennsylvania. In March 2024, Talen Energy sold a data center campus on-site to Amazon Web Services (AWS) for USD 650 million. The plan was simple: Amazon gets carbon-free power at a fixed cost, and Talen gets a premium over the wholesale market rate.

However, in November 2024, FERC rejected a request to increase the amount of power Amazon could take from the plant. This sent a shockwave through the industry, causing the stock prices of independent power producers (IPPs) to plummet.

The December 18 ruling is the “final word” on that dispute. It essentially says: “You can do the deal, but you have to pay the toll.” It creates a standard framework that replaces the “ad-hoc” negotiations that favored companies with the most expensive lawyers.

The Data: The 800% Capacity Jump

The urgency of this ruling is driven by the sheer scale of the power demand. In the PJM region (which covers 65 million people in the Mid-Atlantic), capacity prices for the 2025/2026 period skyrocketed.

Key Statistics:

• PJM Capacity Price Spike: Jumped from USD 28.92/MW-day to USD 269.92/MW-day—an 800% increase.
• Blackwell Power Density: Next-gen AI clusters using NVIDIA Blackwell (documented in recent hardware analysis) operate at 50-100kW per rack, a 10x increase over legacy standards.
• Interconnection Backlog: PJM currently has over 3,000 projects waiting for grid connections, the majority of which are renewables being “held up” by the complexity of large-load data center requests.

Industry Impact

Impact on Big Tech

Companies like Amazon, Microsoft, and Google must now account for higher operational costs in their AI buildouts. The era of “subsidy-by-omission” is over. However, the ruling also provides a clear “menu” of options. For the first time, a tech firm can calculate exactly what a co-location project will cost in grid tolls, which may actually accelerate deals that were previously stuck in legal limbo.

Impact on Renewable Energy

This is a massive win for wind and solar developers. By requiring data centers to pay their share, it prevents the cost of the grid from being shifted onto the general public, which often includes the surcharges used to fund renewable transitions. It also clears the path for “surplus” interconnection, allowing battery storage sites (like the record-breaking battery deployments) to connect more quickly.

Impact on Consumers

By ending the “free ride,” FERC is protecting the average household from seen price spikes. If data centers were allowed skip transmission payments, those costs would have been added to the monthly bills of families in Ohio, Pennsylvania, and Virginia. This ruling preserves the “non-discrimination” principle of the American power grid.

Challenges & Limitations

1. The Reliability Backstop: Even with these rules, the grid operator (PJM) still has the final say. If a project is deemed too risky for the grid, no amount of money can force its approval.
2. State vs. Federal Juries: While FERC manages the high-voltage grid, state regulators manage the distribution lines. Projections suggest secondary legal battles in state courts as utilities try to find new ways to tax these “behind-the-meter” connections.
3. Implementation Lag: Jan 17, 2026, is the filing deadline, but it will likely take all of 2026 for these rules to be fully operational across the PJM footprint.

What’s Next?

Short-Term (H1 2026)

Keep an eye on January 19, 2026. This is the deadline for PJM’s informational report on project status. Market observations suggest a flood of new ISA amendments as Amazon and others scramble to comply with the new “toll road” model.

Medium-Term (2027-2029)

The focus will shift from “co-location” to “Advanced Interconnection.” Expect to see data centers that include their own massive on-site battery storage to help “buffer” their grid usage, potentially avoiding the most expensive transmission fees.

Long-Term (2030+)

The grid will likely bifurcate. Industry trends suggest the rise of truly “islanded” data centers that are never connected to the public grid at all, relying instead on small modular reactors (SMRs) or massive dedicated solar/battery arrays.

What This Means for Industry Stakeholders

The FERC December ruling is a “Great Reset” for the relationship between AI and the energy grid.

For Energy Investors:

• The value of existing nuclear and gas sites just went up. They are now “legalized” hubs for AI, provided the toll is paid.
• Look for companies with high “Surplus Interconnection” capacity.

For Data Center Operators:

• Your CapEx modeling just got more complex. “Behind-the-meter” is no longer a magic word for “free.”
• Invest in demand-response software. If you can prove you can throttle your load, your grid fees will drop significantly.

The “Free Ride” is over, but the road is now paved. The AI revolution will continue, but for the first time, everyone is paying their fair share of the fare.

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