Amazon buys Talen's Cumulus data center campus next to the Susquehanna nuclear plant

Background

Data centers that train and serve AI systems draw power continuously, and their load does not follow the weather or the time of day. Nuclear plants run around the clock and produce carbon-free electricity, which makes them a natural neighbour for a facility with that kind of demand. The conventional route between the two runs through the grid: the plant sells its output into the wholesale market, and the data center buys from the same market like any other large customer. The Susquehanna deal tried something different.

The March 2024 agreement

On 4 March 2024, Talen Energy and Amazon agreed to a deal under which 960 MW of the Susquehanna nuclear plant's output would be sold directly to Amazon Web Services, and Talen agreed to sell its adjacent digital infrastructure campus to AWS for $650 million^[1]. The campus is called Cumulus, and Wikipedia records the March 2024 announcement of its sale to AWS for the same $650 million^[2].

The structure was what made the arrangement notable. The original deal was a behind-the-meter co-location of the data center campus with the nuclear plant: the campus sits alongside the plant and takes its electricity from the plant rather than buying it from the public grid like an ordinary customer^[1]. Under that setup the relationship between the reactor and the servers is essentially a private one, and the power does not reach the wholesale market in the usual way.

A larger agreement in 2025

On 11 June 2025 the two companies expanded the relationship into a new power purchase agreement covering up to 1,920 MW of carbon-free nuclear power through 2042, ramping to the full volume no later than 2032^[3]. That is twice the 960 MW named in the original arrangement. A power purchase agreement (PPA) is a long-term contract in which a buyer commits to take electricity on agreed terms, which is what lets a generator plan and finance years ahead.

From behind the meter to in front of it

Under the expanded PPA, the co-located load arrangement is to transition to a front-of-the-meter structure in spring 2026, with Talen acting as retail supplier and PPL Electric Utilities handling transmission^[3]. In plain terms, the campus stops being a private annex of the power station and becomes a customer of the grid: the electricity still comes from Susquehanna, but the wires, and the transmission service that goes with them, belong to the utility. The change moves a relationship that had been arranged outside the grid back inside the regulated electricity system.

Beyond the contract

The companies also said they would explore building small modular reactors (SMRs) within Talen's Pennsylvania footprint and would pursue plant uprates to add net-new energy to the PJM grid^[3]. An uprate raises a reactor's licensed power output by upgrading its equipment; SMRs are designs built as smaller units, intended to be manufactured in factories and assembled on site. PJM is the wholesale electricity market and grid operator for that part of the country. Kevin Miller, an AWS executive, tied the deal to Amazon's $20 billion investment in Pennsylvania data center campuses, which the company called the largest private-sector investment in state history^[3].

Why it matters

Taken together, the sequence — a co-location purchase in 2024, a long-term PPA in 2025, and a shift to a front-of-the-meter structure in spring 2026 — shows where the difficulty in powering data centers with nuclear energy actually sits. The reactors exist and the demand exists; what has to be settled is the contract, the metering, who pays for transmission, and which regulator has a say. A model in which a data center is bolted directly onto a power station ends up being reshaped to fit the rules of the grid it sits within.