3D-Printed Thermal Storage Units Made of Ultra-High-Performance Concrete

Thermal storage units are a central component of climate-neutral heat supply. Storage systems covering a wide range of sizes and temperature ranges are required for buildings, district and municipal heating networks, and industrial applications. In the DRUCKSTORE project, Fraunhofer ISE, together with IPROconsult, IAB Weimar, and m-tec, is developing new manufacturing methods based on concrete 3D printing using ultra-high-performance concretes (UHPC). This combination aims to enable the production of highly integrated storage units with minimal material usage, thereby creating cost-effective and efficient solutions.

Initial Situation

Thermal storage units are currently mostly made of steel or—particularly for large-scale storage—concrete. Manufacturing these units is labor-intensive, requires multiple trades (e.g., for construction and insulation work), and is comparatively inflexible. At the same time, the energy transition necessitates integrating significantly more thermal storage systems into the energy system to enable the use of renewable heat across various temperature ranges and applications—from buildings and districts to industry. Conventional construction methods are reaching economic and spatial limits. In contrast, 3D concrete printing allows highly flexible and integrated construction and has already been proven in structural building applications, though it has not yet been studied for thermal storage production, especially not using UHPC.

Objective

The goal of DRUCKSTORE is to establish the technical foundations for 3D-printed thermal storage units made of ultra-high-performance concrete (UHPC). This includes increasing functional integration, reducing material usage and CO₂ footprint compared to current storage solutions, and achieving high storage efficiency. By the end of the project, a 3D-printed water storage unit and a high-temperature solid-state storage unit (up to approximately 700 °C) with volumes of up to 8 m³ will be realized. Additionally, design guidelines, engineering tools, and validated simulation models will be developed to plan larger storage systems (100–1000 m³) and assess their economic viability.

Approach

Partners first develop application-specific requirements for storage units, UHPC materials, and 3D printing technology. Fraunhofer ISE optimizes storage geometries (e.g., diffusers, wall structures) using CFD simulations and, with support from m-tec, translates these into 3D-printed functional prototypes. These prototypes are tested and iteratively optimized in ISE’s laboratory. IAB Weimar develops printable UHPC formulations with tailored strength and density, including fiber-reinforced variants and potentially insulating UHPC. m-tec adapts mixing, conveying, and printing technology to UHPC and develops a customized print head. IPROconsult creates engineering tools and design guidelines, particularly for high-temperature storage.

Results

Expected outcomes include printable UHPC materials for water and high-temperature storage, a UHPC-optimized 3D printing system with process data collection, and validated storage components such as diffusers, wall segments, and integrated insulation structures. A fully 3D-printed water storage unit and a high-temperature solid-state storage unit will undergo experimental testing of charging/discharging characteristics, storage efficiency, heat losses, and mechanical durability. Life Cycle Assessment (LCA) and cost analyses will compare CO₂ and cost reduction potential with conventional steel and concrete storage systems, forming the basis for future deployment in district and industrial sectors.

The “DRUCKSTORE” project is funded by the Federal Ministry of Economic Affairs and Energy (BMWE).