WP1 – Concept definition and Techno-economic Optimisation:
Since the project start, the WP1 working group has been focused on defining all main power plant working parameters, such as the optimal charging and discharging times according to power grid demands, maximum CAES pressure, CAES vessel design and design parameters of compressor train and expansion train. A detailed system-level performance model has been developed in Modelica, which allows the performance assessment and optimisation under different boundary conditions.
On the other hand, experimental testing will be done at different scales. The working group will test small solar absorbers (12x12 cm) in the solar furnace at CIEMAT-PSA. Then, larger absorber samples (25x25 cm) will be tested at the solar tower at IMDEA. Finally, during the last project year, a 300 kWth receiver with approximately 1 m2 of aperture area will be tested at a solar tower at CIEMAT-PSA. This receiver will power a hot air turbine that will be connected to a small-scale CAES unit, providing between 1 or 2 hours of nominal turbine mass flow. During the first project year, all prototypes have been defined and specified in detail.
WP2 – Solar Receiver Development:
The CAPTure receiver technology will be further developed considering an advanced ceramic composite material (developed by Walter E.C. Pritzkow Spezialkeramik). The receiver will be tested at different scales from 50 to 300 kWth.
WP3 – Advanced Heat Exchangers:
The ASTERIx-CAESar plant concept requires two separate heat transfer systems: a Low Temperature Heat Exchanger (LTHE) system to carry out the intercooled/ aftercooled compression, and the High Temperature Heat Exchanger (HTHE) system to heat and re-heat the compressed air before the expansion. For both systems, two different concepts will be explored: the classic recuperative concept, where heat transfer occurs between streams separated by a heat transfer surface, and the innovative regenerative concept, where air is cooled/heated in a single vessel by passing through a porous heat storage medium.
WP4 – Advanced CAES and power cycle development and Optimisation:
WP4 is responsible for the development of turbomachinery and the associated integrated systems in ASTERIx-CAESar. This implies three main modules (islands) of the facility: the compression train charging the storage system (whether underground or on surface), the expansion train converting the mechanical (pressurised air) and thermal (high temperature storage medium) energy stored in the system into electricity, and bottoming heat recovery system harvesting any remaining thermal energy downstream of the expanders to produce additional electric power.
WP5 – Automatization and improved plant operation and monitoring via AI methods:
WP5 addresses three main activities:
- High-accuracy & high-precision aiming strategy generation method enhanced with artificial intelligence algorithms. - Advanced optical sensors for monitoring high-concentration solar thermal systems has focused on the use of optical fibers. - AI-based heliostat tracking control system for low-cost operation requires an intensive campaign to collect and label images to store a comprehensive training and validation dataset, enabling improved model performance and greater generalisation across diverse conditions.
WP6 – Validation & Demonstration of receiver and power cycle:
Within the framework of WP6, significant progress has been made in evaluating the thermal behaviour and scaling up the ASTERIx-CAESar solar absorbers and complete prototype. The work package, aimed at validating the concept under real-world conditions, is currently advancing through its initial tasks. A key development in this task involves collaboration between APRIA and CIEMAT on designing a reverse osmosis (RO) desalination unit powered by compressed air from the CAES system.
