The CEEGS project has demonstrated a worldwide first-of-its-kind system for the integration of a transcritical CO₂ electrothermal energy storage cycle with partial geological CO₂ sequestration, elevating the concept to TRL 4. This represents a new class of Carnot battery that is simultaneously an energy storage system and a carbon sequestration tool. A validated laboratory demonstrators achieved the high round-trip efficiencies predicted via theoretical studies (simulation) as well as stable operation (cycling, charge and discharge). The compactness of supercritical CO₂ machinery ensures small footprint. Comparative benchmarks confirm the competitive edge: power to hydrogen depend on critical minerals, while molten-salt PTES is constrained to ~24 h and high-temperature high-cost materials. In contrast, CEEGS uniquely enables multi-day to seasonal storage, is free of rare-earth dependency, addresses large scale, and can be utilized for cogeneration (electricity, heating, and cooling) from a single installation. These data substantiate the performance advantages, showing that CEEGS already delivers laboratory-proven competitiveness against established long-duration storage options.
Addressing target audiences and expressing needs
- Grants and Subsidies
- Other blended financing
- Collaboration
Funding, financing or cooperation for the further development of the technology to TRL 5-6.
- Public or private funding institutions
- International Organisations (ex. OECD, FAO, UN, etc.)
- Research and Technology Organisations
R&D, Technology and Innovation aspects
CEEGS developed a scalable system utilising CO2 for power, possible heat and cooling, and partial CO₂ sequestration, turning surplus renewables into storable thermal energy for on-demand use. A 20 kWel demo raised the tech from TRL2 to TRL4 with EU validation, offering low cost, long duration, and rare-earth independence. Next: demo plant and business plan to reach TRL6.
- Applications from few kWh to several MWh storage,
- Flexible storage duration from hours to weeks,
- Modular construction possible
- Adaptable power ratings
- Standardization potential
- Modular system design,
- Easy to scaled up or down based on local energy demand and storage needs,
- Connection of renewable power plants, industrial CO₂ sources, including cleaning, as a provided of the CO2 and possible user of the stored energy, or district heating/cooling networks without major redesign,
- store excess electricity from any source, improving grid stability in various energy mixes,
- CO₂ injection, geothermal heat extraction, and underground storage already have industrial analogues in oil & gas, CCS (Carbon Capture & Storage), and geothermal power,
- standardized designs for certain storage volumes, reservoir types, and power ratings can be developed → enabling faster rollouts.
- Storage technology without the use of rare earths,
- No ignition or flammability, as CO2 is an inert gas
- No toxic media used
- CO₂ sequestration – decarbonisation of hard -to-abate industry, and possibly negative emissions for sources relying on biomass for power generation, such as pulp&paper sector or waste-to-energy sector
- Excess green electricity, no backup by fossil fuel
- new value chains in renewable energy, energy storage, and CO₂ management
