Constellation Energy Pushes to Restart Three Mile Island Unit 1 in 2027 Despite Grid Connection Delays
Constellation Energy is doubling down on its plan to restart the Crane Clean Energy Center (formerly Three Mile Island Unit 1) in 2027, filing a FERC request to work around transmission bottlenecks that could delay the project until the 2030s.
The Situation
- Plant: Crane Clean Energy Center (formerly TMI Unit 1)
- Capacity: 835 MW (pressurized water reactor)
- Shut down: 1999
- Target restart: 2027 (accelerated from 2028)
- Customer: Microsoft (20-year power purchase agreement)
- Problem: PJM grid operator says transmission upgrades needed until 2031
The Grid Bottleneck
Regional transmission operator PJM has informed Constellation that some transmission upgrades needed for the plant to connect to the grid won't be completed until the 2030s. This threatens the 2027 restart timeline.
Constellation's Solution
CEO Joseph Dominguez announced Constellation is:
- Filing a FERC request to transfer capacity injection rights from its Eddystone plant to Crane
- Working with PJM to accelerate grid connection
- Maintaining the 2027 target despite delays
The Eddystone plant (Pennsylvania) has 380 MW dual-fuel units kept online beyond their planned retirement to ensure grid reliability.
Why It Matters
- Microsoft's AI energy needs: Big Tech's massive power demand is driving nuclear renaissance
- Nuclear comeback: Restarting a closed reactor is faster and cheaper than building new
- Grid infrastructure gap: Transmission bottlenecks are emerging as a critical constraint on clean energy deployment
- Precedent: If successful, this could open the door to restarting other closed nuclear plants
The Irony
Three Mile Island — site of the most famous nuclear accident in US history (Unit 2, 1979) — may now become a symbol of nuclear energy's comeback, providing clean power for AI data centers.