Carnot batteries: What to track
Waiting for the first grid-scale plant to report real results
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)135 | ↗ 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%29 | ↕ volatile | Efficiency decides arbitrage margin. |
| Supply chain | Critical mineral cost and geopolitical concentration | None; steel, nitrate salt, sand, standard turbomachinery2 | → 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 bar5 | → 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 hexane24 | → 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 storage8 | → 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 operating6910 | ↕ 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 20407 | ↗ improving | Sets the size of the prize. |
Sources
- Carnot Battery development: A review on system performance, applications and commercial state-of-the-art (Vecchi et al., Journal of Energy Storage 55, 105782) University of Birmingham repository, 2022
- Review of Carnot Battery Technology Commercial Development (Novotny et al., Energies 15(2), 647) MDPI, 2022
- Advancing Pumped Thermal Energy Storage Performance and Cost Using Silica Storage Media (Applied Energy 387, 125567) National Laboratory of the Rockies (formerly NREL), 2025
- Design-Point Techno-Economics of Brayton Cycle PTES for Combined Heat and Power (Neises and McTigue, GTP-24-1410) NREL (now National Laboratory of the Rockies) / OSTI, 2024
- Lazard's Levelized Cost of Energy+ (LCOE+), July 2026 (LCOS) Lazard, 2026
- Long-duration 'pumped heat energy storage' startup Malta raises US$50 million in Series B round (news report of company claims) Energy-Storage.news, 2021
- Long Duration Energy Storage Council report spotlights opportunity for thermal energy storage (Net-Zero Heat report, press release) LDES Council, 2022
- Comparative and prospective life cycle assessment of residential Carnot batteries (Laterre, Coppitters, Lemort and Contino, 4th International Workshop on Carnot Batteries) UCLouvain DIAL repository, 2024
- World-first 560 C Carnot battery unveiled as SPIC launches ultra-high-temperature heat storage (news report of company claims) ESS News, 2026
- Malta Inc. Store2REPower project breaks ground for full-scale heat exchanger qualifications Energy Storage Europe, 2024