# Carnot batteries: What to track

Waiting for the first grid-scale plant to report real results

Source page: https://www.materialinsights.org/energy/e_carnot/tracking/

What this tab covers The attributes worth tracking regularly, with the latest value, the direction of travel and why each matters.

The key signal is the first grid-scale plant reporting measured efficiency and availability.

| Category | Attribute | Latest | Trend | Why it matters |
|---|---|---|---|---|
| Techno-economic | **LCOS trajectory** | NLR silica PTES USD 115 per MWh (10 h, modelled 2025); reviewed averages USD 230-369; 4-hour lithium USD 210-292 (Lazard 2026)^[1](https://research.birmingham.ac.uk/files/179865334/1_s2.0_S2352152X22017704_main.pdf)^[3](https://research-hub.nrel.gov/en/publications/advancing-pumped-thermal-energy-storage-performance-and-cost-usin/)^[5](https://www.lazard.com/media/kcfconhf/lazards-lcoeplus_vf.pdf) | ↗ improving | Shows whether long-duration costs fall below batteries. |
| Technical | **Measured round-trip efficiency (analogue of state of health)** | SPIC pilot over 65% (company claim, Dec 2025); Isentropic 77% (reduced-power test); Siemens Gamesa rock store about 25%^[2](https://www.mdpi.com/1996-1073/15/2/647)^[9](https://www.ess-news.com/?p=7856) | ↕ volatile | Efficiency decides arbitrage margin. |
| Supply chain | **Critical mineral cost and geopolitical concentration** | None; steel, nitrate salt, sand, standard turbomachinery^[2](https://www.mdpi.com/1996-1073/15/2/647) | → stable | Low exposure to mineral shocks. |
| Market | **Ancillary service market saturation** | Battery LCOS USD 210-292 per MWh at 4 h (Lazard 2026) sets the bar^[5](https://www.lazard.com/media/kcfconhf/lazards-lcoeplus_vf.pdf) | → stable | PTES needs long-duration or capacity payments, not fast frequency markets. |
| Regulatory | **Safety and environmental compliance** | Process-plant rules; some designs use methanol or hexane^[2](https://www.mdpi.com/1996-1073/15/2/647)^[4](https://www.osti.gov/pages/servlets/purl/2448062) | → stable | Flammable cold stores add permitting work. |
| Impact | **Lifecycle carbon payback period** | No payback figure found; home-scale LCA finds impacts driven by PV and grid power, not the storage^[8](https://research.dial.uclouvain.be/bitstreams/e5197ca3-4f5a-4877-bde1-7d99f853f9e1/download) | → stable | Low efficiency means charging power must be clean. |
| Market | **Commercial-scale deployment and developer funding** | SPIC 1 MW / 4 MWh pilot, Beijing (Dec 2025); Malta heat-exchanger tests at DLR (Store2REPower); Malta Series B USD 50 million (2021); no grid-scale PTES operating^[6](https://www.energy-storage.news/long-duration-pumped-heat-energy-storage-startup-malta-raises-us50-million-in-series-b-round/)^[9](https://www.ess-news.com/?p=7856)^[10](https://energystorageeurope.eu/news/malta-inc-store2repower-project-breaks-ground-for-full-scale-heat-exchanger-qualifications/) | ↕ volatile | Bankability needs operating references. |
| Market | **Long-duration storage demand** | LDES Council: thermal storage could help lift long-duration capacity to 2-8 TW by 2040^[7](https://ldescouncil.com/news/long-duration-energy-storage-council-report-spotlights-opportunity-for-thermal-energy-storage-to-advance-the-clean-energy-transition) | ↗ improving | Sets the size of the prize. |

#### Sources

1. [Carnot Battery development: A review on system performance, applications and commercial state-of-the-art (Vecchi et al., Journal of Energy Storage 55, 105782)](https://research.birmingham.ac.uk/files/179865334/1_s2.0_S2352152X22017704_main.pdf) University of Birmingham repository, 2022
2. [Review of Carnot Battery Technology Commercial Development (Novotny et al., Energies 15(2), 647)](https://www.mdpi.com/1996-1073/15/2/647) MDPI, 2022
3. [Advancing Pumped Thermal Energy Storage Performance and Cost Using Silica Storage Media (Applied Energy 387, 125567)](https://research-hub.nrel.gov/en/publications/advancing-pumped-thermal-energy-storage-performance-and-cost-usin/) National Laboratory of the Rockies (formerly NREL), 2025
4. [Design-Point Techno-Economics of Brayton Cycle PTES for Combined Heat and Power (Neises and McTigue, GTP-24-1410)](https://www.osti.gov/pages/servlets/purl/2448062) NREL (now National Laboratory of the Rockies) / OSTI, 2024
5. [Lazard's Levelized Cost of Energy+ (LCOE+), July 2026 (LCOS)](https://www.lazard.com/media/kcfconhf/lazards-lcoeplus_vf.pdf) Lazard, 2026
6. [Long-duration 'pumped heat energy storage' startup Malta raises US$50 million in Series B round (news report of company claims)](https://www.energy-storage.news/long-duration-pumped-heat-energy-storage-startup-malta-raises-us50-million-in-series-b-round/) Energy-Storage.news, 2021
7. [Long Duration Energy Storage Council report spotlights opportunity for thermal energy storage (Net-Zero Heat report, press release)](https://ldescouncil.com/news/long-duration-energy-storage-council-report-spotlights-opportunity-for-thermal-energy-storage-to-advance-the-clean-energy-transition) LDES Council, 2022
8. [Comparative and prospective life cycle assessment of residential Carnot batteries (Laterre, Coppitters, Lemort and Contino, 4th International Workshop on Carnot Batteries)](https://research.dial.uclouvain.be/bitstreams/e5197ca3-4f5a-4877-bde1-7d99f853f9e1/download) UCLouvain DIAL repository, 2024
9. [World-first 560 C Carnot battery unveiled as SPIC launches ultra-high-temperature heat storage (news report of company claims)](https://www.ess-news.com/?p=7856) ESS News, 2026
10. [Malta Inc. Store2REPower project breaks ground for full-scale heat exchanger qualifications](https://energystorageeurope.eu/news/malta-inc-store2repower-project-breaks-ground-for-full-scale-heat-exchanger-qualifications/) Energy Storage Europe, 2024

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_carnot/index.md)
- [Overview](https://www.materialinsights.org/energy/e_carnot/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_carnot/correlation/index.md)
- [Science and technology](https://www.materialinsights.org/energy/e_carnot/sg-sci/index.md)
- [Engineering and performance](https://www.materialinsights.org/energy/e_carnot/sg-eng/index.md)
- [Economics](https://www.materialinsights.org/energy/e_carnot/sg-econ/index.md)
- [Impact and additionality](https://www.materialinsights.org/energy/e_carnot/sg-impact/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_carnot/links/index.md)