Compressed-air and CO2 storage: What to track

Real efficiency, Willow Rock's finance and India's first CO2 plant

Real efficiency, Willow Rock's finance and India's first CO2 plant What this tab covers The attributes worth tracking regularly, with the latest value, the direction of travel and why each matters.

Track whether adiabatic plants meet design efficiency in operation, and whether Willow Rock reaches financial close and construction.

Category	Attribute	Latest	Trend	Why it matters
Techno-economic	LCOS trajectory	About USD 100/MWh at 1,000 MW, 10 h (DOE/PNNL 2022)⁶	↗ improving	Large Chinese builds and longer durations should lower cost per kWh.
Technical	Measured round-trip efficiency (in place of state of health)	Design 72.1% (Feicheng), 64-70% (Yingcheng) (developer figures); 60-65% (Hydrostor estimate); over 75% (Energy Dome claim)¹⁸¹¹¹³	↗ improving	Operating data will show whether the efficiency gap to pumped hydro is closing.
Supply chain	Critical mineral cost and geopolitical concentration	No critical minerals; build led by China¹⁹	→ stable	Risk lies in turbomachinery supply and geology, not minerals.
Market	Ancillary service and capacity market access	Long-term contracts, such as 200 MW over 25 years at Willow Rock³	↗ improving	Lumpy projects need long contracted revenue to be financed.
ESG compliance	Safety and environmental compliance	Pressure, mining and permitting rules; Willow Rock received its final California Energy Commission licence (Dec 2025)²⁰	→ stable	Permitting is now cleared at Willow Rock; elsewhere it remains the main schedule risk.
Climate	Lifecycle carbon payback period	No verified figure found⁴	→ stable	Gas burned in diabatic plants matters; adiabatic plants should be much lower carbon.
Policy	US federal support for Willow Rock	Conditional DOE loan guarantee up to USD 1.76 billion (January 2025); no financial close found in reporting reviewed; company says shovel-ready in 2026³⁴²⁰	↕ volatile	Conditional commitment issued just before a change of administration; watch final close.
Deployment	India and Asia uptake of CO2 and air storage	NTPC Kudgi 160 MWh Energy Dome plant contracted (2025)⁹	↗ improving	First Indian utility deployment of a non-lithium, non-hydro long-duration store.
Deployment	Hydrostor Silver City progress	NSW development agreement approved Feb 2025 (company); AEMO and Transgrid connection approval Sept 2026¹¹¹²	↗ improving	First Hydrostor plant at scale; tests the water-column design and its cost.
Policy	GB cap-and-floor support	TeesCAES (50 MW, 30 h) on Ofgem's June 2026 minded-to list, the only CAES project among 16²¹	↗ improving	A regulated revenue floor is the route to finance for lumpy long-duration plants in Britain.

Sources

'World's largest' compressed air energy storage project connects to the grid in China Energy-Storage.news, 2024
Hydrostor gets $1.76B DOE conditional loan guarantee for compressed air energy storage Utility Dive, 2025
US DOE offers US$1.76 billion loan to Hydrostor for A-CAES California project Energy-Storage.news, 2025
2022 Grid Energy Storage Technology Cost and Performance Assessment US Department of Energy / Pacific Northwest National Laboratory, 2022
Google backs Italian long duration CO2 energy storage technology RenewEconomy, 2025
NTPC joins forces with Energy Dome for CO2 Battery deployment Energy Dome via Business Wire, 2025
Hydrostor secures grid connection for first Australian CAES project ESS News, 2026
Silver City Energy Storage Centre Hydrostor, 2026
World's largest compressed air energy storage power station launched China Daily (Shandong), 2024
World's largest compressed air energy storage project breaks ground in China ESS News, 2024
Hydrostor's Willow Rock Energy Storage Center obtains final approval for power plant licence Hydrostor via Business Wire, 2025
Long Duration Electricity Storage cap and floor Window 1: minded-to decisions (consultation) Ofgem, 2026