innoBeLs

innoBeLs – Innovative Container Concepts for Sustainable Ice Stores

In solar-powered cold district heating networks, ice storage systems are a key technology for seasonal energy storage. However, the concrete tanks currently used, which feature two heat exchanger coil loops made of PE-X (cross-linked polyethylene) and a mounting structure made of aluminum profiles, have significant environmental impacts due to material usage and the primary energy required for manufacturing and disposal.

The innoBeLs research project addresses this issue by developing an innovative and resource-efficient container concept. Based on findings from previous research projects, alternative construction methods such as pit thermal energy stores or gravel-water thermal energy stores are being investigated. Initial analyses indicate that such concepts could reduce environmental impacts and greenhouse gas emissions by up to 50 % and lifecycle costs by approximately one-third. The larger the ice storage capacity, the greater the potential savings.

A key research aspect of innoBeLs is the optimization of the heat exchangers, as their length already reaches several kilometers for a store volume of 100 m³. Innovative design approaches aim to minimize material consumption, costs, and ecological impact. Additionally, the project focuses on the scalability and standardization of the newly developed container solutions to drive cost reductions and promote wider market penetration of this technology.

Another challenge related to latent heat stores like ice stores is the detection of the state of charge, as the charge level can change even at a constant temperature. To address this challenge, reliable and cost-effective solutions are being developed.

To achieve the project goals, both experimental work and thermal, structural, fluid dynamic, and system simulations will be conducted. These studies and simulations will investigate aspects such as ice formation on new container components, the structural stability of the new container concept, the functionality of new state of charge sensors and the system integration of the new container design.

Based on the results of analyzing several newly developed container concepts, a concept for an innovative ice store will be implemented in a pilot plant under real operating conditions, measured, and comprehensively evaluated with regard to economic and ecological impact across its entire lifecycle.

With the growing demand for district heating networks due to current legal requirements in Germany, the use of efficient ice stores is becoming increasingly relevant – especially for new residential areas in combination with cold heating networks and decentralized heat pumps in the individual buildings. The innoBeLs project thus makes an important contribution to the sustainable heat supply of the future.

01/2025 - 12/2028

Scientific Partner:
Institute for Building Energetics, Thermotechnology and Energy Storage (IGTE) at the University of Stuttgart
www.igte.uni-stuttgart.de

Industrial Partner:
Viessmann Deutschland GmbH
www.viessmann.de

The innoBeLs project is funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) based on a resolution of the German Bundestag, through the Project Management Jülich (PTJ) under the grant number 03EN6049. The authors express their gratitude for the support and take full responsibility for the content of this publication.