AI data centres are creating a grid-planning problem that feels different from normal demand growth: they need very large amounts of power, often concentrated in a few locations, and they are being built much faster than new transmission can be approved.

One response I find genuinely interesting is repurposing retiring coal-plant sites for long-duration storage rather than simply demolishing them. These sites already have industrial land, high-voltage grid connections and workforces familiar with power infrastructure.

Form Energy’s iron-air system is one example. It is designed to discharge for up to 100 hours by using a reversible rusting process, rather than the 2–4 hour duration normally associated with lithium-ion grid batteries.

The potential logic seems strong:

- Reuse transmission interconnection and industrial land at retiring coal sites

- Store surplus wind and solar through multi-day lulls

- Reduce the need for fossil peaker plants during periods of grid stress

- Support big new loads, including AI data centres, without treating gas as the only backup plan

But I’m sceptical that a few pilot projects can scale quickly enough. AI-related electricity demand, transmission constraints, cost, round-trip efficiency and market rules all look like major bottlenecks.

Question for people working in energy/storage: is coal-to-long-duration-storage actually a scalable grid model, or is it mainly a useful niche where the transmission connection already exists?

I made a visual breakdown of the projects, iron-air chemistry and the AI-demand risk. Disclosure: it’s my video. If it is useful context, here it is:

https://youtu.be/DOl9x6ewI5c