The Air4NRG project is making significant strides in developing a novel long-duration energy storage solution. At the heart of this effort is a stepwise, iterative prototyping approach, ensuring that each development phase builds on validated results before advancing to the next. A key part of this process is the collaboration between SEGULA Technologies and ABC Compressors, two project partners working on the design and refinement of the system’s prototypes.
A Stepwise Approach to Prototyping
Instead of rushing to a full-scale industrial prototype, Air4NRG is methodically testing and refining its technology. The journey began with a low-pressure test bench, designed by SEGULA, to analyse the system’s core mechanics. This platform allowed engineers to study piston behaviour, energy losses, and compression efficiency, providing crucial data for optimising the system.
Building on these insights, work has now shifted to an intermediate prototype, developed by SEGULA and ABC. This next version will operate at higher pressures and incorporate more complex configurations, bringing the technology closer to its final form. Rather than assembling a fully integrated unit from the outset, engineers are introducing new elements gradually, refining each component before full system integration.
“We are following a structured path,” says David Guyomarc’h, Air4NRG’s Scientific Coordinator. “Rather than building a large-scale system immediately, we are validating each stage step by step to ensure efficiency and reliability.”
While the intermediate prototype takes shape and is going to be tested in Portugal, planning is already underway for the final prototype, which will undergo large-scale testing in Spain. The intermediate testing phase will provide valuable insights, allowing the team to refine key components and system performance before transitioning to the final stage. By the time the large-scale prototype is deployed, it will integrate all optimised elements, ensuring a highly efficient and industrially viable energy storage system.
“Our goal is to ensure that the system functions efficiently under real-world conditions,” adds Guyomarc’h. “The isothermal approach allows us to avoid energy losses and maintain high round-trip efficiency, making this solution both cost-effective and sustainable.”
Engineering Breakthroughs and Challenges
Developing a compressed air energy storage system presents significant technical challenges, particularly in optimising efficiency and system reliability.
One of the most complex issues faced by the team is valve control, which regulates the transfer of compressed air. Precise valve timing is critical for minimising energy losses, and engineers from ABC and SEGULA have dedicated months to refining this mechanism.
Another key innovation has been the heat exchange process. Initially, the team aimed to use a single type of heat exchanger for all compression stages, but research revealed that three distinct heat exchangers—each tailored to different pressure levels—were necessary for optimal performance. This adjustment has improved efficiency and ensured that the system fits within the compact space of a standard container, a core design requirement.
Scaling Up for Industrialisation
As Air4NRG progresses toward industrial deployment, a critical challenge has emerged: European manufacturing constraints. The project has revealed that many European manufacturers rely heavily on foreign components, particularly for gas storage and high-pressure systems.
“Scaling up from a small prototype to a full industrial system is a challenge,” Guyomarc’h acknowledges. “But we are designing every aspect of this technology with future deployment in mind.”
To address this issue, the team is actively exploring ways to source all key components within Europe, reinforcing energy independence and reducing reliance on external supply chains.
Next Steps
With a structured, step-by-step development strategy, Air4NRG is well-positioned to deliver a scalable, efficient energy storage solution. The intermediate prototype is set for assembly in April, followed by high-pressure testing on the upgraded test bench. These tests will provide essential performance data, guiding refinements for the final industrial version.
As the project moves forward, rapid prototyping, real-world validation, and strong industrial partnerships remain key drivers. Air4NRG is not only advancing a breakthrough energy storage technology—it is shaping the future of sustainable and resilient European energy systems.

For more information on the Air4NRG project and its mission, visit our website at www.air4nrg.eu.

About Air4NRG: Air4NRG is a Horizon Europe-funded project aimed at developing an innovative and sustainable energy storage solution based on isothermal compressed air technology.