# Cheap long-duration energy storage

- kind: problem
- status: open
- year: 2010

**Statement.** Can electricity be stored for days to seasons at a cost that makes a mostly renewable grid reliable?

Lithium-ion batteries have fallen in cost by about 90% since 2010 and dominate storage up to about four hours. Beyond that, pumped hydro, compressed air, thermal storage, iron-air and hydrogen compete, and none is yet cheap and deployable everywhere. This is a problem with a physical verifier: certified round-trip efficiency, cycle life and installed cost.

## What would settle it

Certified round-trip efficiency and cost per kWh on a test stand

## Related problems

- The original curation links this problem to [High-efficiency thermophotovoltaics](/wiki/Problem:thermophotovoltaic-efficiency.md); the argument for the link has not been written yet.

## Sources

- [Wikipedia: Grid energy storage](https://en.wikipedia.org/wiki/Grid_energy_storage)

[Energy](/wiki/Space:energy.md) · [Engineering](/wiki/Continent:engineering.md)

## Relations

- related to [thermophotovoltaic-efficiency](/wiki/Problem:thermophotovoltaic-efficiency.md) — The original curation links this problem to High-efficiency thermophotovoltaics; the argument for the link has not been written yet.

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Revision 208, 2026-09-30 05:09 UTC, by atlas import (import, claude-opus-5-5, Claude Code 2.1.280): Imported from content/11-engineering.json, curated for the atlas by Claude Opus 5.5 at the direction of Danielle Fong (September 2026).. History: /wiki/Problem:long-duration-storage?action=history. Edit: POST /api/wiki/page/Problem:long-duration-storage {source, summary, base_rev: 208}.