Periodic Reporting for period 1 - Air4NRG (Air isothermal compression technology for long term energy storage)
Période du rapport: 2024-01-01 au 2025-06-30
Context and overall objectives of the project
The transition towards a climate-neutral Europe requires reliable, long-duration energy storage solutions to balance the increasing share of intermittent renewable generation. Current dominant technologies, such as pumped-storage hydroelectricity, face geographical limitations, while existing Compressed Air Energy Storage (CAES) plants have historically suffered from low efficiencies, reliance on fossil fuels, and the need for underground storage. In this context, the European Union has identified the development of sustainable, efficient, and scalable storage systems as a strategic priority for energy security, competitiveness, and the achievement of the Green Deal targets.
Air4NRG addresses this need by developing an innovative Isothermal Compressed Air Energy Storage (I-CAES) solution, targeting a round-trip efficiency above 70%. The project will deliver two prototypes: a plug-and-play system in a standard 40ft container, providing over ten hours of storage, and a larger-scale 200 kW unit. Both are conceived as rare material-free, safe, and cost-efficient solutions, designed to be fully manufacturable within the EU and easily integrated into the grid through advanced energy management systems (EMS).
Project pathway to impact
The project follows a structured pathway:
Design and optimisation of the isothermal compression/expansion process, regenerative heat exchangers, and system control algorithms.
Prototype development and validation under industrial conditions, including testing in a relevant environment (TRL5) to demonstrate operational efficiency, reliability, and safety.
Sustainability and socio-economic validation, applying a life-cycle approach (environmental, economic, and social assessments) to ensure the technology’s viability and societal acceptance.
Market analysis and integration into European electricity grids, addressing regulatory, standardisation, and business model aspects to facilitate scalability and replication.
Exploitation, dissemination, and communication, engaging policymakers, industry, academia, civil society, and media to accelerate adoption, strengthen EU technological leadership, and ensure long-term competitiveness.
Through this pathway, Air4NRG is expected to:
Increase the availability and robustness of sustainable long-term energy storage in Europe.
Enhance energy system flexibility and resilience, enabling greater penetration of renewable energy.
Reduce lifecycle costs by up to 40% compared to lithium-ion batteries, while tripling service life.
Minimise environmental impacts, with an expected 60% reduction in carbon footprint compared to lithium-ion technologies and a land use reduction of up to 80% compared to pumped hydro.
Create new high-skilled jobs and stimulate the European energy storage value chain.
Role of Social Sciences and Humanities (SSH)
Although the project is mainly technology-driven, SSH integration plays a central role in ensuring societal acceptance and maximising impact. A Social Life Cycle Assessment (S-LCA) will be carried out to analyse stakeholder perceptions, societal readiness, and acceptance barriers, feeding into tailored communication and exploitation strategies. Furthermore, the project will explicitly consider gender equality, responsible research and innovation (RRI) principles, and the Sustainable Development Goals, ensuring that Air4NRG contributes to a just, inclusive, and sustainable energy transition.
The transition towards a climate-neutral Europe requires reliable, long-duration energy storage solutions to balance the increasing share of intermittent renewable generation. Current dominant technologies, such as pumped-storage hydroelectricity, face geographical limitations, while existing Compressed Air Energy Storage (CAES) plants have historically suffered from low efficiencies, reliance on fossil fuels, and the need for underground storage. In this context, the European Union has identified the development of sustainable, efficient, and scalable storage systems as a strategic priority for energy security, competitiveness, and the achievement of the Green Deal targets.
Air4NRG addresses this need by developing an innovative Isothermal Compressed Air Energy Storage (I-CAES) solution, targeting a round-trip efficiency above 70%. The project will deliver two prototypes: a plug-and-play system in a standard 40ft container, providing over ten hours of storage, and a larger-scale 200 kW unit. Both are conceived as rare material-free, safe, and cost-efficient solutions, designed to be fully manufacturable within the EU and easily integrated into the grid through advanced energy management systems (EMS).
Project pathway to impact
The project follows a structured pathway:
Design and optimisation of the isothermal compression/expansion process, regenerative heat exchangers, and system control algorithms.
Prototype development and validation under industrial conditions, including testing in a relevant environment (TRL5) to demonstrate operational efficiency, reliability, and safety.
Sustainability and socio-economic validation, applying a life-cycle approach (environmental, economic, and social assessments) to ensure the technology’s viability and societal acceptance.
Market analysis and integration into European electricity grids, addressing regulatory, standardisation, and business model aspects to facilitate scalability and replication.
Exploitation, dissemination, and communication, engaging policymakers, industry, academia, civil society, and media to accelerate adoption, strengthen EU technological leadership, and ensure long-term competitiveness.
Through this pathway, Air4NRG is expected to:
Increase the availability and robustness of sustainable long-term energy storage in Europe.
Enhance energy system flexibility and resilience, enabling greater penetration of renewable energy.
Reduce lifecycle costs by up to 40% compared to lithium-ion batteries, while tripling service life.
Minimise environmental impacts, with an expected 60% reduction in carbon footprint compared to lithium-ion technologies and a land use reduction of up to 80% compared to pumped hydro.
Create new high-skilled jobs and stimulate the European energy storage value chain.
Role of Social Sciences and Humanities (SSH)
Although the project is mainly technology-driven, SSH integration plays a central role in ensuring societal acceptance and maximising impact. A Social Life Cycle Assessment (S-LCA) will be carried out to analyse stakeholder perceptions, societal readiness, and acceptance barriers, feeding into tailored communication and exploitation strategies. Furthermore, the project will explicitly consider gender equality, responsible research and innovation (RRI) principles, and the Sustainable Development Goals, ensuring that Air4NRG contributes to a just, inclusive, and sustainable energy transition.
During the first 18 months, Air4NRG has successfully advanced from laboratory-scale validation towards the design and optimisation of its innovative Isothermal Compressed Air Energy Storage (I-CAES) concept. The focus of this period has been the consolidation of system specifications, modelling, and the development of intermediate components leading to the prototype phase.
System design and optimisation : A complete dynamic simulation model has been developed to represent the compression/expansion process, providing the foundation for design validation and performance optimisation. Detailed engineering studies for the containerised prototype (200 kW, 1 MWh capacity) have been finalised, including CAD drawings for the compressor, regenerative heat exchangers (RHE), and control logic. An upgraded test bench at IMT Atlantique has been employed to assess efficiency and validate control algorithms under various operational scenarios. Preliminary results demonstrate promising thermodynamic efficiency above 95% at component level, confirming the feasibility of achieving >70% round-trip efficiency at system scale.
Prototype development: The first manufacturing steps have been initiated, based on the designs produced under WP2. Industrial components for the innovative compressor stages and the optimised RHE are under production, with early assembly and integration activities already progressing. In parallel, an intermediate prototype has been upgraded and prepared for future validation at EDP LABELEC facilities, ensuring a smooth transition towards TRL5 testing in the second half of the project.
Sustainability validation: A preliminary eco-design assessment has been completed, applying life-cycle thinking to guide design choices. This includes the selection of materials with reduced environmental footprint and improved circularity. In addition, a techno-economic analysis has identified cost hotspots, providing recommendations for cost optimisation ahead of the prototype phase. A first round of stakeholder consultations has been launched to support the upcoming Social LCA.
System design and optimisation : A complete dynamic simulation model has been developed to represent the compression/expansion process, providing the foundation for design validation and performance optimisation. Detailed engineering studies for the containerised prototype (200 kW, 1 MWh capacity) have been finalised, including CAD drawings for the compressor, regenerative heat exchangers (RHE), and control logic. An upgraded test bench at IMT Atlantique has been employed to assess efficiency and validate control algorithms under various operational scenarios. Preliminary results demonstrate promising thermodynamic efficiency above 95% at component level, confirming the feasibility of achieving >70% round-trip efficiency at system scale.
Prototype development: The first manufacturing steps have been initiated, based on the designs produced under WP2. Industrial components for the innovative compressor stages and the optimised RHE are under production, with early assembly and integration activities already progressing. In parallel, an intermediate prototype has been upgraded and prepared for future validation at EDP LABELEC facilities, ensuring a smooth transition towards TRL5 testing in the second half of the project.
Sustainability validation: A preliminary eco-design assessment has been completed, applying life-cycle thinking to guide design choices. This includes the selection of materials with reduced environmental footprint and improved circularity. In addition, a techno-economic analysis has identified cost hotspots, providing recommendations for cost optimisation ahead of the prototype phase. A first round of stakeholder consultations has been launched to support the upcoming Social LCA.
At this stage of the project (M18), Air4NRG has generated significant scientific and technical results that already indicate its potential to transform the long-term energy storage landscape. The dynamic simulation model, advanced compressor and regenerative heat exchanger (RHE) designs, and upgraded test bench validation demonstrate the feasibility of achieving round-trip efficiencies above 70%. Preliminary eco-design assessments also confirm the capacity of the solution to drastically reduce environmental footprint compared to lithium-ion batteries and pumped hydro, while maintaining high robustness and long service life.
The project is expected to deliver two containerised prototypes that will serve as first-of-their-kind demonstrations of isothermal CAES at TRL5. These prototypes will not only validate the scientific novelty of the approach but also open pathways for replication and scale-up in multiple market segments, from utility-scale renewable integration to decentralised industrial storage.
The project is expected to deliver two containerised prototypes that will serve as first-of-their-kind demonstrations of isothermal CAES at TRL5. These prototypes will not only validate the scientific novelty of the approach but also open pathways for replication and scale-up in multiple market segments, from utility-scale renewable integration to decentralised industrial storage.